Named and Described in 1983:
Adasaurus (AD-uh-SAW-rus)
From Wikipedia
Adasaurus ("Ada's lizard") is a genus of dromaeosaurid theropod dinosaur from the Late Cretaceous Period of what is now Central Asia. It was a small bipedal carnivore with a sickle-shaped claw on the second toe of each hind foot. An adult was perhaps about 1.8 m (5.9 ft) long.
Ada is an evil spirit in the national mythology of Mongolia. The name also includes the Greek word sauros meaning 'lizard', the most common suffix used in dinosaur names. There is one species (A. mongoliensis), named after the country of Mongolia, where the fossil was found. Both genus and species were named and described in 1983 by famous Mongolian paleontologist Rinchen Barsbold.
Adasaurus is a member of Dromaeosauridae, a theropod family thought to be very closely related to birds. Relationships within the family are poorly understood, but Adasaurus seems to be a member of the subfamily Dromaeosaurinae, along with the Mongolian Achillobator and several North American species.
Other dromaeosaurids include Deinonychus, Velociraptor, Microraptor, and Buitreraptor. Adasaurus is unique among dromaeosaurids in having much smaller sickle claws on its hind feet.
Two specimens of Adasaurus have been found, both from the Nemegt Formation of Bayankhongor Province in Mongolia. The holotype is an incomplete skull associated with some bones of the skeleton, including all three bones of the pelvis. The second specimen, also described in the original paper, consists of the back end of another skeleton, including the hindlimbs. Both specimens are currently in the collection of the Mongolian Geological Institute in Ulaanbaatar, Mongolia.
The age of the Nemegt, like most of Mongolia's Late Cretaceous sediments, is not known for certain, but it is commonly thought to belong to the Maastrichtian stage of the Late Cretaceous Period. Therefore the Nemegt was deposited somewhere between 74 and 65 million years ago. Other dinosaurs found in this formation include Tarbosaurus, Anserimimus, and Saurolophus.
Tuesday, May 31, 2011
'Heller of a good golf time
CalgarySun (Canada): 'Heller of a good golf time '
These days, there are countless lost golf balls littered across the Badlands.
But before golfers were digging up divots at Drumheller’s Dinosaur Trail Golf & Country Club, palaeontologists were scouring the historic site for a different sort of artifact.
“Even now, the grounds crew — the people that have been here a number of years — will recognize some fossils and some plant fauna and things like that,” said Scott Westman, the GM at Dinosaur Trail.
“Every year, with the rain and snow, there’s always something getting exposed.”
Since the completion of its one-of-a-kind back nine in 1996, Dinosaur Trail has been exposed as one of the hidden gems on Alberta’s golf scene.
Pin-seekers affectionately refer to the halfway point of their round as ‘the turn.’ In the case of Dinosaur Trail, a 6,409-yard public track located about 120 km northeast of Calgary and just a couple of wedge shots down the road from the world-famous Royal Tyrell Museum, that’s when the course really turns into something special.
The front nine opened in 1965 and is an old-school stroll under the shade of tree-lined fairways.
The finishing stretch, on the other hand, is carved out of the coulees and features more ups and downs than the back side of a stegosaurus.
“It’s a different kind of golf experience — it’s something very unique,” Westman said.
“The front nine is a very gentle park-like setting and a more traditional style. Then you jump across the highway and get into a totally different land. Things tighten up, and it’s a little more scenic and up and down. As we tell people, it’s a very unique experience — not just playing but visually as well.”
The scenery is spectacular. The tough part is keeping your golf ball from becoming a part of it.
From the launch pad at
No. 11, you might wonder where the rest of the fairway is hiding. Alberta-based course architect Sid Puddicombe initially envisioned a more generous landing area, but the hole had to be re-configured because of the possibility of a dinosaur skeleton buried in the hillside.
At the tricky 12th, there’s so much danger surrounding the dance-floor you’ll feel like you’re firing at an island green, even though there’s not a drop of water in sight.
And the most talked-about test at Dinosaur Trail is undoubtedly No. 14, which features a staircase-style fairway and a map that details your options from the tee-box.
You might never find another golf hole that’s anything like it.
In fact, you could make the same statement about the entire course.
“As tough as it is, we still get people coming back that are high-handicaps but want to play because it’s just so different,” Westman said.
“I think, sometimes, with a course being so tough, people will say, ‘I’m not coming back. I lose too many balls.’ But people keep coming back here to experience it year after year.
“Here’s something I don’t hear very much — ‘I used the same ball the whole way around,’ ” he added.
“But we hear words like challenging and picturesque. We’ll hear, ‘Wow, I lost six balls,’ but they might’ve found six, as well.”
Who knows? You might find a fossil, too.
Dinosaur trackway reveals new species
USAToday-Science Fair: Dinosaur trackway reveals new species
Chinese paleontologists report the discovery of roughly 125 dinosaur footprints in a trackway more than 100 million years old. Tridactyl theropod tracks from the Zhucheng site.
CAPTIONElsevier, Cretaceous Research
The find points to at least one new species, reports the team led by Rihui Li of the Chinese Geological Survey in the Cretaceous Research journal, and adds to evidence that northeastern China saw a landscape dominated by birds and two-legged theropod dinosaurs in the era from 146 to 100 million years ago.
Researchers first turned up the trackway in 2006, and it underwent four years of measurement and excavation. The analysis finds at least three types of dinosaurs left their footprints in the mud that fossilized to form the trackway.
"The largest morphotype (kind) is a large theropod represented by a single trackway and an isolated natural cast," write the authors, finding the creature had a foot about 11 inches long. The others had feet only about 5 inches long and one appears to be a newly-discovered species, which the authors named, Corpulentapus lilasia, which roughly means "stout-footed lily of the East".
Paleontologists particularly relish trackway sites as indicators of behavior and gait in dinosaurs and other extinct animals. Parallel tracks have demonstrated some dinosaurs were social creatures who traveled in groups, for example.
Chinese paleontologists report the discovery of roughly 125 dinosaur footprints in a trackway more than 100 million years old. Tridactyl theropod tracks from the Zhucheng site.
CAPTIONElsevier, Cretaceous Research
The find points to at least one new species, reports the team led by Rihui Li of the Chinese Geological Survey in the Cretaceous Research journal, and adds to evidence that northeastern China saw a landscape dominated by birds and two-legged theropod dinosaurs in the era from 146 to 100 million years ago.
Researchers first turned up the trackway in 2006, and it underwent four years of measurement and excavation. The analysis finds at least three types of dinosaurs left their footprints in the mud that fossilized to form the trackway.
"The largest morphotype (kind) is a large theropod represented by a single trackway and an isolated natural cast," write the authors, finding the creature had a foot about 11 inches long. The others had feet only about 5 inches long and one appears to be a newly-discovered species, which the authors named, Corpulentapus lilasia, which roughly means "stout-footed lily of the East".
Paleontologists particularly relish trackway sites as indicators of behavior and gait in dinosaurs and other extinct animals. Parallel tracks have demonstrated some dinosaurs were social creatures who traveled in groups, for example.
Friday, May 27, 2011
Weekend Highlight: DINOSAURS: Explore ... Escape ... Survive!
COSI - Center of Science and Industry
333 West Broad Street
Columbus, OH 43215
NBC4i.com: Weekend Highlight: DINOSAURS: Explore ... Escape ... Survive!
OPENS MAY 28th
EXPLORE: Everything we know about dinosaurs has come from their bones. We don't know exactly what they looked like but we can get a pretty good ideas from bones. See what a dinosaur may have looked like 250 million years ago as you take a stroll through their world and see scientifically accurate animatronic dinosaurs, complete with movement and sound. View footprints, casts and real fossil teeth and bones.
ESCAPE: Dig for fossils, unearth secrets of the Mesozoic Era and measure your prehistoric knowledge through this interactive, 3,000 square foot maze. Learn how dinosaurs survived millions of years ago and Make Tracks in the Triassic!
SURVIVE: This interactive experience gives visitors an opportunity to test their survival skills int eh Mesozoic era. Become a T. Rex and use its keen sense of hearing to hunt, feed and survive life 250 million years ago. Be a dinosaur is a fun interactive way to learn more about dinosaurs!
DATES & TIMES: May 28 - September 05 Monday - Saturday: 10 am - 5 pm; Sunday: 12 - 6 pm OPEN MONDAY, MAY 30th
LOCATION: COSI
COST: Adults: $14.25; Seniors (60+): $13.25; Youth (2 - 12): $9.25
CONTACT INFORMATION: 614-228-2674 or http://cosi.org/visitors/exhibits/dinos
Thursday, May 26, 2011
Volunteer's years of work expose a new dinosaur
Standard-Examiner.com: Volunteer's years of work expose a new dinosaur
HARRISBURG, Pa. -- For 11 years, Kevin Dermody had volunteered his time in the State Museum of Pennsylvania, laboring over a hulking chunk of mudstone in the exhibit area, chipping away with tiny tools as visitors watched him work.
Over time, he exposed a jagged panorama of fragile bones hundreds of millions of years old, excavated from a quarry in New Mexico rich in remnants of prehistoric life. To Dermody and others who devote themselves to solving the mysteries of the ancients, the fossils were routine -- all from well-documented species of dinosaurs.
All along, it turns out, the find of a lifetime was there in the mudstone, right under Dermody's nose.
While chipping away one day in 2004, he exposed the skull and neck of a curious creature with razor-sharp protruding teeth and a stubby snout. He went to his boss, Bob Sullivan. "The teeth, the eye sockets, the snout were different than the dinosaur remains excavated from that site," said Sullivan, senior curator of paleontology at the State Museum. "We had something unique."
This much Sullivan knew: Teeth that sharp belonged to a meat-eater. It traveled on two legs and lived about 200 million years ago.
Next, Sullivan brought in the heavyweights -- David Berman, curator of vertebrate paleontology at the Carnegie Museum of Natural History in Pittsburgh, and Hans-Dieter Sues of the Smithsonian Institution, a specialist in dinosaurs of the Triassic era -- who carefully removed the chunk containing the remains for further study.
"Ninety-five percent of the fossils (found) are known, but every so often you get something odd," said Sues, who was the first to formally identify the skeleton as the remains of a new dinosaur. "It was unlike anything I had seen."
The immense front teeth, with blades serrated like knives, identified it as a "new predatory kind of dinosaur," Sues said
Unlike in the movies, one expert's opinion did not a dinosaur make. Plenty more hands-on work to fully uncover the skeleton fragment followed, which set in motion the long academic vetting process, ending only last month with the publication of a scholarly article in the British journal Proceedings of the Royal Society B.
That was cause for celebration in the State Museum in Harrisburg -- which in recent years, thanks to serial budget cuts and layoffs, hadn't had much to celebrate.
Sues, who co-wrote the article, said the discovery helped fill the evolutionary gap between dinosaurs that lived in South America about 230 million years ago and those that came later, such as the fabled Tyrannosaurus rex.
"It was the link between the early and the late meat-eating dinosaurs," said Sues, who got naming rights. He dubbed the creature Daemonosaurus chauliodus -- "evil-spirit lizard" with "buck teeth."
The undiscovered Daemonosaurus was brought to Pennsylvania almost two decades ago through a random act of inter-museum cooperation.
The Carnegie Museum lent massive blocks of mudstone to museums across the country in 1993. One of the recipients was the State Museum in Harrisburg.
The blocks -- 8 feet wide and 8 feet long, as if a giant had baked brownies -- were the bounty from a major excavation at the world-renowned Ghost Ranch quarry in New Mexico. That treasure trove of fossils was discovered by a Philadelphia paleontologist, Edward Drinker Cope, in the 1880s.
The State Museum's slice was so large and so heavy (several tons) that the National Guard was called in to transport it the 200 miles from Pittsburgh to Harrisburg.
The State Museum proceeded to build a new Dino Lab around the mudstone block -- and installed Dermody to begin the slow, delicate process of chipping.
He gradually brought the exhibit to life as he whittled away at the stone behind a glass window -- sometimes arranging himself on a cushion to reach the inside of the block.
Dermody smiles when he thinks about that day in 2004.
"It was a dream come true for any paleontologist," he said. He has since finished work on the remaining section of the block, and has moved on to studying other fossil remains.
But the story of the world's newest dinosaur is far from over.
The remains are being returned to the Carnegie Museum. Sullivan said he feared visitors would get to see only a picture of the dinosaur in the State Museum, because the bones were too fragile to make a cast replica for display.
But Sues was more optimistic, saying last week that the Smithsonian's conservators believe the bones can withstand the casting process after all.
Meanwhile, the search continues for the rest of the paleontological puzzle.
Sues said other bits of the skeleton may be buried in the adjoining sections of mudstone that were lent to other museums. That mudstone, he said, is where the creature he identified perished -- along with countless other ancients -- in some catastrophic event, likely a flash flood.
He has sent out an all-points bulletin to about 20 museums to be on the lookout for additional skeletal remains of Daemonosaurus.
Sues said he was confident that researchers one day would find the pieces and paint a full picture of the bucktoothed demon lizard that once roamed the earth.
HARRISBURG, Pa. -- For 11 years, Kevin Dermody had volunteered his time in the State Museum of Pennsylvania, laboring over a hulking chunk of mudstone in the exhibit area, chipping away with tiny tools as visitors watched him work.
Over time, he exposed a jagged panorama of fragile bones hundreds of millions of years old, excavated from a quarry in New Mexico rich in remnants of prehistoric life. To Dermody and others who devote themselves to solving the mysteries of the ancients, the fossils were routine -- all from well-documented species of dinosaurs.
All along, it turns out, the find of a lifetime was there in the mudstone, right under Dermody's nose.
While chipping away one day in 2004, he exposed the skull and neck of a curious creature with razor-sharp protruding teeth and a stubby snout. He went to his boss, Bob Sullivan. "The teeth, the eye sockets, the snout were different than the dinosaur remains excavated from that site," said Sullivan, senior curator of paleontology at the State Museum. "We had something unique."
This much Sullivan knew: Teeth that sharp belonged to a meat-eater. It traveled on two legs and lived about 200 million years ago.
Next, Sullivan brought in the heavyweights -- David Berman, curator of vertebrate paleontology at the Carnegie Museum of Natural History in Pittsburgh, and Hans-Dieter Sues of the Smithsonian Institution, a specialist in dinosaurs of the Triassic era -- who carefully removed the chunk containing the remains for further study.
"Ninety-five percent of the fossils (found) are known, but every so often you get something odd," said Sues, who was the first to formally identify the skeleton as the remains of a new dinosaur. "It was unlike anything I had seen."
The immense front teeth, with blades serrated like knives, identified it as a "new predatory kind of dinosaur," Sues said
Unlike in the movies, one expert's opinion did not a dinosaur make. Plenty more hands-on work to fully uncover the skeleton fragment followed, which set in motion the long academic vetting process, ending only last month with the publication of a scholarly article in the British journal Proceedings of the Royal Society B.
That was cause for celebration in the State Museum in Harrisburg -- which in recent years, thanks to serial budget cuts and layoffs, hadn't had much to celebrate.
Sues, who co-wrote the article, said the discovery helped fill the evolutionary gap between dinosaurs that lived in South America about 230 million years ago and those that came later, such as the fabled Tyrannosaurus rex.
"It was the link between the early and the late meat-eating dinosaurs," said Sues, who got naming rights. He dubbed the creature Daemonosaurus chauliodus -- "evil-spirit lizard" with "buck teeth."
The undiscovered Daemonosaurus was brought to Pennsylvania almost two decades ago through a random act of inter-museum cooperation.
The Carnegie Museum lent massive blocks of mudstone to museums across the country in 1993. One of the recipients was the State Museum in Harrisburg.
The blocks -- 8 feet wide and 8 feet long, as if a giant had baked brownies -- were the bounty from a major excavation at the world-renowned Ghost Ranch quarry in New Mexico. That treasure trove of fossils was discovered by a Philadelphia paleontologist, Edward Drinker Cope, in the 1880s.
The State Museum's slice was so large and so heavy (several tons) that the National Guard was called in to transport it the 200 miles from Pittsburgh to Harrisburg.
The State Museum proceeded to build a new Dino Lab around the mudstone block -- and installed Dermody to begin the slow, delicate process of chipping.
He gradually brought the exhibit to life as he whittled away at the stone behind a glass window -- sometimes arranging himself on a cushion to reach the inside of the block.
Dermody smiles when he thinks about that day in 2004.
"It was a dream come true for any paleontologist," he said. He has since finished work on the remaining section of the block, and has moved on to studying other fossil remains.
But the story of the world's newest dinosaur is far from over.
The remains are being returned to the Carnegie Museum. Sullivan said he feared visitors would get to see only a picture of the dinosaur in the State Museum, because the bones were too fragile to make a cast replica for display.
But Sues was more optimistic, saying last week that the Smithsonian's conservators believe the bones can withstand the casting process after all.
Meanwhile, the search continues for the rest of the paleontological puzzle.
Sues said other bits of the skeleton may be buried in the adjoining sections of mudstone that were lent to other museums. That mudstone, he said, is where the creature he identified perished -- along with countless other ancients -- in some catastrophic event, likely a flash flood.
He has sent out an all-points bulletin to about 20 museums to be on the lookout for additional skeletal remains of Daemonosaurus.
Sues said he was confident that researchers one day would find the pieces and paint a full picture of the bucktoothed demon lizard that once roamed the earth.
Wednesday, May 25, 2011
Magnet school first-graders take hands-on approach to studying dinosaurs
DenverPost: Magnet school first-graders take hands-on approach to studying dinosaurs
NORTHGLENN — Aidan Hartman squatted near the 152 million-year-old fossil and studied it with a critical eye.
The only other dinosaur bones he had seen before Monday were in a museum and were well- scrubbed, connected and intact. But this piece, excavated by a group of Northglenn High School educators just a few months ago, held a special fascination for the 7-year-old.
"It confused me," said Aidan. "I've always wondered what a dinosaur would feel like. And this is nothing I've seen before."
Not surprisingly, Aidan came away with another revelation.
"I think it would really be cool to be a paleontologist when I grow up," he said.
It was then that teacher Kent Hups realized he had achieved his goal.
"Science is all about getting teachers excited and especially getting kids excited," Hups said. "Maybe we've done that here."
Aidan is among 50 first-graders at Adams 12 Five Star Schools' Magnet Lab STEM School who will now study the 400-pound sauropod fossil, write about it and prepare the piece for display at the Cañon City Dinosaur Depot Museum.
It's all part of the mission of the school, the first K-8 STEM (science, technology, engineering, math) magnet school in Colorado, said principal Penny Eucker.
"They are taking notes, writing about what they find and applying their knowledge of fossils and infusing technology into what they are doing," Eucker said.
The school will keep the bones for about two years, Hups said. The sauropod was a long- necked plant-eater who was about 60 to 70 feet long and roamed the area that is now Colorado and Wyoming.
Hups and the group from Northglenn High excavated the bones in March from the Hups/Lowell Quarry 25 miles south of Grand Junction. Hups works in conjunction with the Bureau of Land Management and its regional paleontologist Harley Armstrong at the excavation site.
Hups appeared on a panel at STEM School and became convinced it was an ideal place to study the fossil.
"I don't think a group of kids this young had ever worked on something like this, so I thought it would be a fantastic opportunity," he said.
The bones appear to be from a sauropod's vertebrae and, although old, they are pretty sturdy and can hold up well to young, prying hands, Hups said.
This type of opportunity to work on actual dinosaur bones would have stunned Hups when he was the age of the STEM students.
"I just would have wet my pants," he said.
NORTHGLENN — Aidan Hartman squatted near the 152 million-year-old fossil and studied it with a critical eye.
The only other dinosaur bones he had seen before Monday were in a museum and were well- scrubbed, connected and intact. But this piece, excavated by a group of Northglenn High School educators just a few months ago, held a special fascination for the 7-year-old.
"It confused me," said Aidan. "I've always wondered what a dinosaur would feel like. And this is nothing I've seen before."
Not surprisingly, Aidan came away with another revelation.
"I think it would really be cool to be a paleontologist when I grow up," he said.
It was then that teacher Kent Hups realized he had achieved his goal.
"Science is all about getting teachers excited and especially getting kids excited," Hups said. "Maybe we've done that here."
Aidan is among 50 first-graders at Adams 12 Five Star Schools' Magnet Lab STEM School who will now study the 400-pound sauropod fossil, write about it and prepare the piece for display at the Cañon City Dinosaur Depot Museum.
It's all part of the mission of the school, the first K-8 STEM (science, technology, engineering, math) magnet school in Colorado, said principal Penny Eucker.
"They are taking notes, writing about what they find and applying their knowledge of fossils and infusing technology into what they are doing," Eucker said.
The school will keep the bones for about two years, Hups said. The sauropod was a long- necked plant-eater who was about 60 to 70 feet long and roamed the area that is now Colorado and Wyoming.
Hups and the group from Northglenn High excavated the bones in March from the Hups/Lowell Quarry 25 miles south of Grand Junction. Hups works in conjunction with the Bureau of Land Management and its regional paleontologist Harley Armstrong at the excavation site.
Hups appeared on a panel at STEM School and became convinced it was an ideal place to study the fossil.
"I don't think a group of kids this young had ever worked on something like this, so I thought it would be a fantastic opportunity," he said.
The bones appear to be from a sauropod's vertebrae and, although old, they are pretty sturdy and can hold up well to young, prying hands, Hups said.
This type of opportunity to work on actual dinosaur bones would have stunned Hups when he was the age of the STEM students.
"I just would have wet my pants," he said.
Dinosaur catches fire at Ohio amusement park
GoogleNews: Dinosaur catches fire at Ohio amusement park
MASON, Ohio (AP) — A dinosaur has caught fire during work on an Ohio amusement park's own version of "Jurassic Park," sending up a long plume of smoke that drew the attention of people traveling on a nearby interstate highway.
No one was hurt. Spokesman Don Helbig at Kings Island in the Cincinnati area says the park's new "Dinosaurs Alive!" attraction will still have its scheduled grand opening on Thursday.
He tells multiple media outlets that Tuesday's fire broke out during construction, after the park's 8 p.m. closing time. Helbig says the cause is unclear and that the fire was confined to just one of the 60 life-sized animatronic dinosaurs that move and make sounds.
Billowing smoke was captured on video by people traveling on Interstate 71, alongside Kings Island.
MASON, Ohio (AP) — A dinosaur has caught fire during work on an Ohio amusement park's own version of "Jurassic Park," sending up a long plume of smoke that drew the attention of people traveling on a nearby interstate highway.
No one was hurt. Spokesman Don Helbig at Kings Island in the Cincinnati area says the park's new "Dinosaurs Alive!" attraction will still have its scheduled grand opening on Thursday.
He tells multiple media outlets that Tuesday's fire broke out during construction, after the park's 8 p.m. closing time. Helbig says the cause is unclear and that the fire was confined to just one of the 60 life-sized animatronic dinosaurs that move and make sounds.
Billowing smoke was captured on video by people traveling on Interstate 71, alongside Kings Island.
Tuesday, May 24, 2011
Evolution, sex and dinosaur necks
BBC Nature Wonder Monkey Blog: Evolution, sex and dinosaur necks
They are among the largest and most fascinating creatures ever to have walked the Earth.
I’m talking about sauropods, the group of four legged dinosaurs that are almost instantly recognisable due to their long necks, each of which reaches out to a small head, and long tails.
Among the sauropods is the famous Diplodocus, and less well known, but even more remarkable species such as Argentinosaurus, which holds the record for being both the heaviest land animal ever, and the longest.
But what have these giants got to do with sex?
Well scientists are debating what exactly caused these huge reptiles to evolve their huge necks.
A recent theory proposed is that sex, or more accurately sexual selection, was the main driver.
The idea is that down the generations, male sauropods evolved ever longer necks to dominate rivals for the affections of females.
Dinosaurs are long dead, making it harder to test ideas about why certain traits evolved, and what they were adapted for. But evidence can still be brought to bear to analyse the different hypotheses.
For example, for much of the 20th century, sauropods were imagined to be water-loving beasts, which lived or spent much of their time in water, using their long necks as snorkels.
In the 1970s that idea fell into disrepute as multiple lines of evidence, since validated, showed sauropods to be mainly land-going animals.
That then led palaeontologists to imagine that sauropods used their long necks to reach huge amounts of vegetation – enough to yield the energy needed by their huge bodies.
A long neck, the reasoning goes, enabled Argentinosaurus and its ilk to graze plant material from a large “envelope”, from ground grasses to leaves in trees many metres high.
But then along came the sexual selection hypothesis, first proposed in 2006.
It argues that male sauropods that inherited a longer neck, caused by a chance mutation, would be more attractive to females.
The length of their neck would signal their virility and suitability as a sire.
Neck thumpers (image: Arup Shah / NPL)
A long neck could also have been used to wrestle competitor males, dominating them, just as male giraffes often joust by “necking" and "head clubbing" one another, with males with the longest necks and heaviest heads tending to win. Galapagos tortoises may also use the length of their necks to establish dominance.
Long necked males should therefore sire more offspring, on average, and pass down the long-necked genes, driving the trait through the population.
Just as palaeontologists argued over whether sauropods were terrestrial or aquatic beasts, they are now debating the merits of whether sexual selection or eating vegetation explains the long neck of the Diplodocus and others.
And the sexual selection idea has just been examined in detail, and dismissed.
Dr Mike Taylor of the University of Bristol and colleagues tested the arguments put forward to support the idea, and found them wanting.
Firstly, they say there is no evidence in the fossil record of a sauropod species that has males with relatively longer necks than females, or visa versa, which would be expected if it was a "sexy" trait.
While is impossible to witness whether extinct dinosaurs “necked” as giraffes do, their fossilised bones suggest they did not – they do not become any thicker to resist the blows, which would be expected, or show any signs of trauma associated with such behaviour.
There are a host of other more technical reasons for why a long neck wasn’t a sexy neck, Taylor and colleagues describe in the Journal of Zoology.
Their arguments are pretty convincing.
Such debates occur more often than you might expect, at least when it comes to sexually selected traits.
An eye for the females? (image: Phillipe Clement / NPL)
For example, there is still no firm agreement as to whether female peacocks find the elaborate trains of male peacocks attractive (length and eyespot number play a role, though precisely what is unclear).
There have also been similar debates about why giraffes have such long necks.
Indeed the proposal that the giraffe evolved its long neck as a sexual signal led to the proposal that sauropods do similar.
But in 2009, that hypothesis finally bit the dust after Professor Graham Mitchell of the University of Wyoming, in Laramie, US, and colleagues put the sexual selection hypothesis to the test by examining 17 male and 21 female giraffes.
They found if long necks were a sexually selected trait, they expected to find a number of things:
Long necks should be more exaggerated in males than females.
They should evolve to be bigger in size more than other parts of a giraffe's body.
They should confer no immediate benefit to survival, and may come at a cost.
Their results didn't support any of these propositions.
This refutation is similar to that by Dr Taylor and his colleagues. Sauropod necks aren’t more exaggerated in males than females, and they aren’t particularly costly.
Dr Taylor’s team make one final point.
There is no example, anywhere, of a type of four-legged animal, of which there are many species, that has evolved a single trait to be sexy. Crabs evolve big claws to show off, some flies evolve giant eye stalks, birds of paradise shake their sexy tail feathers.
But dinosaurs? Not likely it seems.
A sexy neck just didn’t get the reptilian juices flowing.
Monday, May 23, 2011
Brevard Zoo team heads to Wyoming in search of dinosaur bones
Florida Today: Brevard Zoo team heads to Wyoming in search of dinosaur bones
Chris DeLorey grins like a kid anticipating summer vacation.
Though he's 45, the Brevard Zoo education director channels the eager enthusiasm of a 12-year-old boy as he talks about this week's fossil dig in Wyoming.
"There's something about being the first person to dig up bones that are 70 million years old," he said, eyes wide, voice filled with wonder. It still is a thrill for him, even though he's been making the trip out west for about 15 years.
And it's an experience he's excited about sharing with seven zoo supporters.
The group flew to Wyoming over the weekend. This week, they'll be searching for fossils on a ranch in Lusk, Wyo., with J.D. Cavigeli, a dinosaur paleontologist for the Tate Museum in Casper.
"We're getting to go into some brand-new areas," DeLorey said.
The group, made of zoo members, volunteers and donors, will learn fossil-hunting basics at the museum, then head out to the ranch where they will help unearth a partial triceratops skeleton, a partial duckbill dinosaur skeleton and anything else they can find.
Larger discoveries will be encased in plaster, brought back and displayed at the Brevard Zoo. The fossil hunters, most of whom are paying their way on the trip, get to keep smaller finds.
Cavigeli will lead the expedition. A few summers ago, he discovered the largest T. rex skeleton found in North America, DeLorey said. If the Brevard group happens upon anything rare or important, Cavigeli will decide if it should stay in Wyoming.
DeLorey started in the zoo business working at Busch Gardens. He found a fossilized shark's tooth in a pile of shells, and his interest was piqued.
While teaching earth science in middle school, he took a class in paleontology and became a self-described fossil fanatic.
"Plus, I never grew up," he said, flashing that grin again. "I'm still fascinated by dinosaurs."
If the week of digging is successful, DeLorey will return later to drive their finds back to Florida. Larger bones, when encased in protective plaster cocoons, can weigh more than 2,000 pounds.
Then he and a team at the zoo will begin carefully chipping away the plaster and cleaning off the fossilized bones. He's hoping to have a partial display ready in time for the zoo's Reptile Weekend, set for Labor Day. Final unveiling -- again, if everything goes as planned -- will be Feb. 18, when the zoo brings back the popular animatronic dinosaur exhibit.
Billings Productions, a Texas company that creates the lifelike prehistoric creatures, made a donation to offset some of the costs of the Wyoming trip, as did private donors, including zoo supporter Herb Harvis.
DeLorey said he hopes to turn the trip into an annual excursion. He also would like to develop a natural history display at the zoo, one that gets guest thinking about animals of the past, creatures living now and what animal life might be like in the future.
For now, though, he's itching to get digging. His only problem with traveling to Wyoming?
"When I go out there, it's hard for me to come home."
The trip combines western adventure with exciting history.
"It's a beautiful area," he said. "And we're digging dinosaurs."
Chris DeLorey grins like a kid anticipating summer vacation.
Though he's 45, the Brevard Zoo education director channels the eager enthusiasm of a 12-year-old boy as he talks about this week's fossil dig in Wyoming.
"There's something about being the first person to dig up bones that are 70 million years old," he said, eyes wide, voice filled with wonder. It still is a thrill for him, even though he's been making the trip out west for about 15 years.
And it's an experience he's excited about sharing with seven zoo supporters.
The group flew to Wyoming over the weekend. This week, they'll be searching for fossils on a ranch in Lusk, Wyo., with J.D. Cavigeli, a dinosaur paleontologist for the Tate Museum in Casper.
"We're getting to go into some brand-new areas," DeLorey said.
The group, made of zoo members, volunteers and donors, will learn fossil-hunting basics at the museum, then head out to the ranch where they will help unearth a partial triceratops skeleton, a partial duckbill dinosaur skeleton and anything else they can find.
Larger discoveries will be encased in plaster, brought back and displayed at the Brevard Zoo. The fossil hunters, most of whom are paying their way on the trip, get to keep smaller finds.
Cavigeli will lead the expedition. A few summers ago, he discovered the largest T. rex skeleton found in North America, DeLorey said. If the Brevard group happens upon anything rare or important, Cavigeli will decide if it should stay in Wyoming.
DeLorey started in the zoo business working at Busch Gardens. He found a fossilized shark's tooth in a pile of shells, and his interest was piqued.
While teaching earth science in middle school, he took a class in paleontology and became a self-described fossil fanatic.
"Plus, I never grew up," he said, flashing that grin again. "I'm still fascinated by dinosaurs."
If the week of digging is successful, DeLorey will return later to drive their finds back to Florida. Larger bones, when encased in protective plaster cocoons, can weigh more than 2,000 pounds.
Then he and a team at the zoo will begin carefully chipping away the plaster and cleaning off the fossilized bones. He's hoping to have a partial display ready in time for the zoo's Reptile Weekend, set for Labor Day. Final unveiling -- again, if everything goes as planned -- will be Feb. 18, when the zoo brings back the popular animatronic dinosaur exhibit.
Billings Productions, a Texas company that creates the lifelike prehistoric creatures, made a donation to offset some of the costs of the Wyoming trip, as did private donors, including zoo supporter Herb Harvis.
DeLorey said he hopes to turn the trip into an annual excursion. He also would like to develop a natural history display at the zoo, one that gets guest thinking about animals of the past, creatures living now and what animal life might be like in the future.
For now, though, he's itching to get digging. His only problem with traveling to Wyoming?
"When I go out there, it's hard for me to come home."
The trip combines western adventure with exciting history.
"It's a beautiful area," he said. "And we're digging dinosaurs."
Pa. State Museum volunteer chipped away until he found a new dinosaur
The discovery of Deaemonosaurus chauliodus continued to be in the news...
Philly.com: Pa. State Museum volunteer chipped away until he found a new dinosaur
HARRISBURG - For 11 years, Kevin Dermody had volunteered his time in the State Museum of Pennsylvania, laboring over a hulking chunk of mudstone in the exhibit area, chipping away with tiny tools as visitors watched him work.
Over time, he exposed a jagged panorama of fragile bones hundreds of millions of years old, excavated from a quarry in New Mexico rich in remnants of prehistoric life.
To Dermody and others who devote themselves to solving the mysteries of the ancients, the fossils were routine - all from well-documented species of dinosaurs.
All along, it turns out, the find of a lifetime was there in the mudstone, right under Dermody's nose.
While chipping away one day in 2004, he exposed the skull and neck of a curious creature with razor-sharp protruding teeth and a snubby snout.
He went to his boss, Bob Sullivan.
"The teeth, the eye sockets, the snout were different than the dinosaur remains excavated from that site," said Sullivan, senior curator of paleontology at the State Museum. "We had something unique."
This much Sullivan knew: Teeth that sharp belonged to a meat-eater. It traveled on two legs and lived about 200 million years ago.
Next, Sullivan brought in the heavyweights - David Berman, curator of vertebrate paleontology at the Carnegie Museum of Natural History in Pittsburgh, and Hans-Dieter Sues of the Smithsonian Institution, a specialist in dinosaurs of the Triassic era - who carefully removed the chunk containing the remains for further study.
"Ninety-five percent of the fossils [found] are known, but every so often you get something odd," said Sues, who was the first to formally identify the skeleton as the remains of a new dinosaur. "It was unlike anything I had seen."
The immense front teeth, with blades serrated like knives, identified it as a "new predatory kind of dinosaur," Sues said
Unlike in the movies, one expert's opinion did not a dinosaur make. Plenty more hands-on work to fully uncover the skeleton fragment followed, which set in motion the long academic vetting process, ending only last month with the publication of a scholarly article in the British journal Proceedings of the Royal Society B.
That was cause for celebration in the State Museum in Harrisburg - which in recent years, thanks to serial budget cuts and layoffs, hadn't had much to celebrate.
Sues, who cowrote the article, said the discovery helped fill the evolutionary gap between dinosaurs that lived in South America about 230 million years ago and those that came later, such as the fabled Tyrannosaurus rex.
"It was the link between the early and the late meat-eating dinosaurs," said Sues, who got naming rights. He dubbed the creature Daemonosaurus chauliodus - "evil-spirit lizard" with "buck teeth."
The undiscovered Daemonosaurus was brought to Pennsylvania almost two decades ago through a random act of inter-museum cooperation.
The Carnegie Museum lent massive blocks of mudstone to museums across the country in 1993. One of the recipients was the State Museum in Harrisburg.
The blocks - eight feet wide and eight feet long, as if a giant had baked brownies - were the bounty from a major excavation at the world-renowned Ghost Ranch quarry in New Mexico. That treasure trove of fossils was discovered by a Philadelphia paleontologist, Edward Drinker Cope, in the 1880s.
The State Museum's slice was so large and so heavy (several tons) that the National Guard was called in to transport it the 200 miles from Pittsburgh to Harrisburg.
The State Museum proceeded to build a new Dino Lab around the mudstone block - and installed Dermody to begin the slow, delicate process of chipping.
He gradually brought the exhibit to life as he whittled away at the stone behind a glass window - sometimes arranging himself on a cushion to reach the inside of the block.
Dermody smiles when he thinks about that day in 2004.
"It was a dream come true for any paleontologist," he said. He has since finished work on the remaining section of the block, and has moved on to studying other fossil remains.
But the story of the world's newest dinosaur is far from over.
The remains are being returned to the Carnegie Museum. Sullivan said he feared visitors would get to see only a picture of the dinosaur in the State Museum, because the bones were too fragile to make a cast replica for display.
But Sues was more optimistic, saying Thursday that the Smithsonian's conservators believe the bones can withstand the casting process after all.
Meanwhile, the search continues for the rest of the paleontological puzzle.
Sues said other bits of the skeleton may be buried in the adjoining sections of mudstone that were lent to other museums. That mudstone, he said, is where the creature he identified perished - along with countless other ancients - in some catastrophic event, likely a flash flood.
He has sent out an all-points bulletin to about 20 museums to be on the lookout for additional skeletal remains of Daemonosaurus.
Sues said he was confident that researchers one day would find the pieces and paint a full picture of the bucktoothed demon lizard that once roamed the earth.
Friday, May 20, 2011
Acrocanthosaurus
Dinosaur Discovery Chronicles: The first Acrocanthosaurus bones were found in southeastern Oklahoma and unearthed by Cephis Hall and Sid Love. They sold it to Grafham Enterprises of Ardmore, Okla. There is one named species (A. atokensis), which is named after Atoka County in Oklahoma, where the original specimens were found. The name was coined in 1950 by American paleontologists J. Willis Stovall and Wann Langston, Jr. Langston had proposed the name "Acracanthus atokaensis" for the genus and species in his unpublished 1947 master's thesis, but the name was changed to Acrocanthosaurus atokensis for formal publication.
Mounted Acrocanthosaurus skeleton (NCSM 14345) at the North Carolina Museum of Natural Sciences.
Acrocanthosaurus(ACK-roh-KAN-thuh-SAW-rus), meaning 'high-spined lizard') is a genus of theropod dinosaur that existed in what is now North America during the Aptian and early Albian stages of the Early Cretaceous. Like most dinosaur genera, Acrocanthosaurus contains only a single species, A. atokensis. Its fossil remains are found mainly in the U.S. states of Oklahoma and Texas, although teeth attributed to Acrocanthosaurus have been found as far east as Maryland.
Acrocanthosaurus was a bipedal predator. As the name suggests, it is best known for the high neural spines on many of its vertebrae, which most likely supported a ridge of muscle over the animal's neck, back and hips. Acrocanthosaurus was one of the largest theropods, approaching 12 meters (40 ft) in length, and weighing up to 6–7 metric tons (6.5–7.5 short tons). Large theropod footprints discovered in Texas may have been made by Acrocanthosaurus, although there is no direct association with skeletal remains.
Recent discoveries have elucidated many details of its anatomy, allowing for specialized studies focusing on its brain structure and forelimb function. Acrocanthosaurus was the largest theropod in its ecosystem and likely an apex predator which possibly preyed on large sauropods and ornithopods.
Discovery and naming
Acrocanthosaurus is named for its tall neural spines, from the Greek akra ('high'), akantha ('thorn' or 'spine') and sauros ('lizard').
There is one named species (A. atokensis), which is named after Atoka County in Oklahoma, where the original specimens were found. The name was coined in 1950 by American paleontologists J. Willis Stovall and Wann Langston, Jr. Langston had proposed the name "Acracanthus atokaensis" for the genus and species in his unpublished 1947 master's thesis, but the name was changed to Acrocanthosaurus atokensis for formal publication.
The holotype and paratype (OMNH 10146 and OMNH 10147), described at the same time in 1950, consist of two partial skeletons and a piece of skull material from the Antlers Formation in Oklahoma.
Two much more complete specimens were described in the 1990s. The first (SMU 74646) is a partial skeleton, missing most of the skull, recovered from the Twin Mountains Formation of Texas and currently part of the Fort Worth Museum of Science and History collection.
An even more complete skeleton (NCSM 14345, nicknamed 'Fran') was recovered from the Antlers Formation of Oklahoma by private collectors, prepared by the Black Hills Institute in South Dakota, and is now housed at the North Carolina Museum of Natural Sciences in Raleigh. This specimen is the largest and includes the only known complete skull and forelimb.
Skeletal elements of OMNH 10147 are almost the same size as comparable bones in NCSM 14345, indicating an animal of roughly the same size, while the holotype and SMU 74646 are significantly smaller.
Acrocanthosaurus may be known from less complete remains outside of Oklahoma and Texas. A tooth from southern Arizona has been referred to the genus, and matching tooth marks have been found in sauropod bones from the same area. Several teeth from the Arundel Formation of Maryland have been described as almost identical to those of Acrocanthosaurus and may represent an eastern representative of the genus. Many other teeth and bones from various geologic formations throughout the western United States have also been referred to Acrocanthosaurus, but most of these have been misidentified.
More info
It’s very, very rare. Only four skeletal specimens have been found and most of the remainder are fragments or teeth. The Museum’s Acrocanthosaurus specimen is the best yet unearthed, with 54 percent of the bones represented, and the only one with a complete skull.Before this specimen was discovered, paleontologists couldn’t even determine the dinosaur’s general appearance. One other museum has a cast of Acro, but the N.C. Museum of Natural Sciences is the only place in the world to see the actual fossil.
Mounted Acrocanthosaurus skeleton (NCSM 14345) at the North Carolina Museum of Natural Sciences.
Acrocanthosaurus(ACK-roh-KAN-thuh-SAW-rus), meaning 'high-spined lizard') is a genus of theropod dinosaur that existed in what is now North America during the Aptian and early Albian stages of the Early Cretaceous. Like most dinosaur genera, Acrocanthosaurus contains only a single species, A. atokensis. Its fossil remains are found mainly in the U.S. states of Oklahoma and Texas, although teeth attributed to Acrocanthosaurus have been found as far east as Maryland.
Acrocanthosaurus was a bipedal predator. As the name suggests, it is best known for the high neural spines on many of its vertebrae, which most likely supported a ridge of muscle over the animal's neck, back and hips. Acrocanthosaurus was one of the largest theropods, approaching 12 meters (40 ft) in length, and weighing up to 6–7 metric tons (6.5–7.5 short tons). Large theropod footprints discovered in Texas may have been made by Acrocanthosaurus, although there is no direct association with skeletal remains.
Recent discoveries have elucidated many details of its anatomy, allowing for specialized studies focusing on its brain structure and forelimb function. Acrocanthosaurus was the largest theropod in its ecosystem and likely an apex predator which possibly preyed on large sauropods and ornithopods.
Discovery and naming
Acrocanthosaurus is named for its tall neural spines, from the Greek akra ('high'), akantha ('thorn' or 'spine') and sauros ('lizard').
There is one named species (A. atokensis), which is named after Atoka County in Oklahoma, where the original specimens were found. The name was coined in 1950 by American paleontologists J. Willis Stovall and Wann Langston, Jr. Langston had proposed the name "Acracanthus atokaensis" for the genus and species in his unpublished 1947 master's thesis, but the name was changed to Acrocanthosaurus atokensis for formal publication.
The holotype and paratype (OMNH 10146 and OMNH 10147), described at the same time in 1950, consist of two partial skeletons and a piece of skull material from the Antlers Formation in Oklahoma.
Two much more complete specimens were described in the 1990s. The first (SMU 74646) is a partial skeleton, missing most of the skull, recovered from the Twin Mountains Formation of Texas and currently part of the Fort Worth Museum of Science and History collection.
An even more complete skeleton (NCSM 14345, nicknamed 'Fran') was recovered from the Antlers Formation of Oklahoma by private collectors, prepared by the Black Hills Institute in South Dakota, and is now housed at the North Carolina Museum of Natural Sciences in Raleigh. This specimen is the largest and includes the only known complete skull and forelimb.
Skeletal elements of OMNH 10147 are almost the same size as comparable bones in NCSM 14345, indicating an animal of roughly the same size, while the holotype and SMU 74646 are significantly smaller.
Acrocanthosaurus may be known from less complete remains outside of Oklahoma and Texas. A tooth from southern Arizona has been referred to the genus, and matching tooth marks have been found in sauropod bones from the same area. Several teeth from the Arundel Formation of Maryland have been described as almost identical to those of Acrocanthosaurus and may represent an eastern representative of the genus. Many other teeth and bones from various geologic formations throughout the western United States have also been referred to Acrocanthosaurus, but most of these have been misidentified.
More info
It’s very, very rare. Only four skeletal specimens have been found and most of the remainder are fragments or teeth. The Museum’s Acrocanthosaurus specimen is the best yet unearthed, with 54 percent of the bones represented, and the only one with a complete skull.Before this specimen was discovered, paleontologists couldn’t even determine the dinosaur’s general appearance. One other museum has a cast of Acro, but the N.C. Museum of Natural Sciences is the only place in the world to see the actual fossil.
Tarbosaurus Gangs: What Do We Know?
Smithsonian.com - Dinosaur Tracking: Tarbosaurus Gangs: What Do We Know?
Tarbosaurus, the great tyrannosaur of Cretaceous Mongolia, hunted in packs. That is the exceptional claim made by University of Alberta paleontologist Philip Currie in a press release, and news outlets all over the world have picked up the story. Just imagine rapacious tyrannosaur families tearing over the prehistoric countryside; it is a terrifying notion that the press release heralds as a “groundbreaking” discovery that will forever change paleontology.
But does the actual evidence live up to all the hype? Unfortunately, the answer is no. The proposal of pack-hunting dinosaurs is old news in paleontological circles, and the hard evidence to support the claims about Tarbosaurus has not yet been released.
Packaged under the theme “Dino Gangs,” the media release, book, and cable-network documentary arranged by Atlantic Productions hinge on a Tarbosaurus bonebed found in Mongolia’s Gobi Desert. The site was one of 90 Tarbosaurus localities surveyed by Currie and the Korea-Mongolia International Dinosaur Project, but it is unique in that it preserves the remains of six individual animals of different life stages. How the animals died and became buried is unknown. Even so, the press claims that these dinosaurs were a single family group that hunted together.
There was no scientific paper attached to the release, and I received no reply from Atlantic Productions when I inquired whether a technical description of the site will soon be published. The media release–reporting conclusions without providing evidence–was presented on its own.
This is not the first time tyrannosaurs have been reconstructed as living in packs. In 1997 Currie relocated a rich dinosaur bonebed in Alberta, Canada that had been discovered by the fossil hunter Barnum Brown in 1905. The site was dominated by remains of the tyrannosaur Albertosaurus—at least a dozen individuals of this species were found in this one place. Why one site should contain so many tyrannosaurs was difficult to explain, but in a 1998 paper published in Gaia, Currie proposed that the Albertosaurus were living in a social group and that the site was evidence of gregarious behavior among the dinosaurs. More than that, Currie proposed that there was a “division of labor” within the Albertosaurus packs. Compared with the adults, juvenile Albertosaurus would have been much faster runners thanks to their different leg proportions, and so Currie suggested: “The faster, more agile juveniles may have been responsible for driving potential prey towards the larger, more powerful adult tyrannosaurids.” Currie has suggested the same thing for Tarbosaurus in the “Dino Gangs” press release.
But the idea that young and old tyrannosaurs worked together to tackle prey rests upon the inference that the bonebeds contain social groups. This is not necessarily so. There are many ways to make a bonebed, and the fine geological details of such fossil-rich sites contain essential information about how the bodies of the different individuals became preserved together. Proximity does not always indicate sociality, as Currie himself noted in a paper published with David Eberth last year about the Albertosaurus quarry.
Although the idea that the Albertosaurus quarry indicates complex social interactions among pack-hunting dinosaurs is a sexy hypothesis, Currie and Eberth noted that the animals could have been brought into close association by some kind of environmental catastrophe. “[T]he evidence for a significant storm and associated flooding event at the [Albertosaurus] site and in the surrounding area is well documented,” the scientists wrote, and they suggested that solitary Albertosaurus might have been driven together into a small area by the floodwaters. Pack behavior among the animals could not be taken as a given. The Albertosaurus were together when they died, but exactly how they died and why they were so close to each other remains unclear.
In the 2005 book Carnivorous Dinosaurs, Currie and several co-authors reported on a bonebed found in Montana that contained several hadrosaurs and remains of three tyrannosaurs identified as Daspletosaurus. Though the scientists suggested that the tyrannosaurs might have been interacting socially before they died, how the animals died and became buried was unknown. The same was true of a site in Argentina described by Currie and colleague Rodolfo Coria. The bonebed contained seven individuals of a large predatory dinosaur unrelated to tyrannosaurs named Mapusaurus. Although the site could have represented a social group, Currie and Coria concluded that “It is conceivable that this bonebed represents a long term or coincidental accumulation of carcasses.”
There is no slam-dunk evidence that tyrannosaurs or other large predatory dinosaurs hunted in packs. Even in the case of Deinonychus—a small, sickle-clawed “raptor” traditionally thought to be a cooperative hunter—evidence of multiple individuals in association with prey species has recently been questioned. In the end, trackways that record the footsteps of multiple raptors moving together has provided better evidence that these dinosaurs were sometimes social. No such evidence exists for tyrannosaurs yet. (Only one footprint attributed to a tyrannosaur has been found so far.)
Various processes can bring bones together into a single fossil deposit. A bonebed might represent a social group killed and buried by a flood, scattered bodies or bones that were washed together by water currents, or a natural trap where multiple individual animals died over a long period of time, among other possibilities. How the animals died, how long it took for the fossil deposit to accumulate, and other questions must be answered before hypotheses about behavior can be drawn out. As for the Tarbosaurus bonebed, no technical details of the site have yet been released. There is no science to talk about at this point. The site might record the death of a dinosaur pack, but that is just one of many possibilities that have yet to be ruled out.
The hubbub over the “Dino Gangs” press release is intensely frustrating. No scientific information is available, and the supposedly jaw-dropping findings are almost exactly the same as those proposed on the basis of a different site in 1998. The press release is full of bombastic language about how it is now time to rewrite the dinosaur books and how this discovery will forever change our understanding of dinosaur behavior. None of the information provided so far will do any such thing. The new find is one more discovery that will add to our understanding of dinosaurs, but is not wildly different from what has been discovered or proposed before. If there is something truly exceptional about the Tarbosaurus bonebed, it has yet to be revealed.
A discovery isn’t important simply because a press release says it is. Scientific findings should not be judged by how glitzy a documentary is or how well a book sells. By the sound of it, Currie and his colleagues have found a spectacular fossil site that is brimming with information about prehistoric life. None of the details have been published yet, and, consequently, they have not been submitted to the process of scientific debate, so no one can definitively say how the Tarbosaurus bonebed will affect our understanding of these dinosaurs. The discovery of the fossil site is just one part of the story. The rest, including how the Tarbosaurus lived and died, will take time to draw out.
References:
Coria, R., and Currie, P. (2006). A new carcharodontosaurid (Dinosauria, Theropoda) from the Upper Cretaceous of Argentina Geodiversitas, 28 (1), 71-118
Currie, P. (1998). POSSIBLE EVIDENCE OF GREGARIOUS BEHAVIOR IN TYRANNOSAURIDS Gaia, 271-277
Currie, P., & Eberth, D. (2010). On gregarious behavior in Albertosaurus Canadian Journal of Earth Sciences, 47 (9), 1277-1289 DOI: 10.1139/E10-072
Currie, P.; Trexler, D.; Koppelhus, E.; Wicks, K.; Murphy, N. (2005) An unusual multi-individual, tyrannosaurid bonebed in the Two Medicine Formation (Late Cretaceous, Campanian) of Montana (USA), in Carpenter, K. (ed.), The Carnivorous Dinosaurs. Indiana University Press, Bloomington; Indianapolis: 313-324.
Thursday, May 19, 2011
Dallas, Texas: Own Your Own Dinosaur
KZTV10: Own Your Own Dinosaur
DALLAS - Ancient history is being put up for auction in Dallas. Four authentic dinosaur skeletons will be sold next month at the biggest dinosaur auction of its kind. "Truly, these things are priceless. They are almost irreplaceable," said Ron Tykoski a paleontologist at the Museum of Nature and Science in Dallas.
On June 12, some bidders will name a price. An almost complete Triceratops skeleton is expected to sell for at least $700,000 An Allosaurus and a Stegosaurus known as "The Fighting Pair" are thought to fetch $2.8 million. It's quite an investment for something hundreds of millions of years old.
So, who buys? "There are private clients. There are famous people. There are people who buy it and donate it to museums," said Peter Wiggins with Heritage Auction Galleries. The other three skeletons, a colossal fish, a Maiasaura and a huge ground sloth, are warehoused in crates.
Those who can't afford to bid but want to see the dinosaurs can view them publicly at the Tower Building in Dallas' Fair Park from June 8-12.
DALLAS - Ancient history is being put up for auction in Dallas. Four authentic dinosaur skeletons will be sold next month at the biggest dinosaur auction of its kind. "Truly, these things are priceless. They are almost irreplaceable," said Ron Tykoski a paleontologist at the Museum of Nature and Science in Dallas.
On June 12, some bidders will name a price. An almost complete Triceratops skeleton is expected to sell for at least $700,000 An Allosaurus and a Stegosaurus known as "The Fighting Pair" are thought to fetch $2.8 million. It's quite an investment for something hundreds of millions of years old.
So, who buys? "There are private clients. There are famous people. There are people who buy it and donate it to museums," said Peter Wiggins with Heritage Auction Galleries. The other three skeletons, a colossal fish, a Maiasaura and a huge ground sloth, are warehoused in crates.
Those who can't afford to bid but want to see the dinosaurs can view them publicly at the Tower Building in Dallas' Fair Park from June 8-12.
Wednesday, May 18, 2011
Some dinosaurs may soon go extinct from record books
DailyIndia.com: Some dinosaurs may soon go extinct from record books
Washington, May 18: Certain dinosaurs may soon go extinct from the record books because they are duplicates of animals already on the books.
John Horner, a paleontologist at Montana State University, and others suspect that at least 50 dinosaurs on the record books now have been incorrectly identified.
Paleontologist Michael J. Benton at the University of Bristol said that up to 51.7 percent of all dinosaur species are miscategorized.
He said that's a "frightening figure. This means that more than half the species of dinosaurs ever named were in error."
Horner added that at present, "new" dinosaurs are discovered and named at a rate of one every two weeks. Thousands of dinosaurs are now on record, with many of them probably being duplicates of animals already on the books.
Horner, who has two dinosaurs named after him, is proposing that paleontologists follow a rigorous set of procedures known as the Unified Frame of Reference (UFR) when attempting to identify fossils.
The UFR will take into account microscopic analysis of the fossils, which uses technologies not available in the past.
It will also require detailed analysis of where the remains were found, how they appeared when first observed pre-excavation, how they compare to existing species, and more.
"The proposals by Horner are very important as a reminder of a problem paleontologists are aware of, but we still don't know if it will provide a 100 percent watertight solution that means we will never make mistakes about dinosaur species ever again," said Benton.
The study was reported in Science journal.
Washington, May 18: Certain dinosaurs may soon go extinct from the record books because they are duplicates of animals already on the books.
John Horner, a paleontologist at Montana State University, and others suspect that at least 50 dinosaurs on the record books now have been incorrectly identified.
Paleontologist Michael J. Benton at the University of Bristol said that up to 51.7 percent of all dinosaur species are miscategorized.
He said that's a "frightening figure. This means that more than half the species of dinosaurs ever named were in error."
Horner added that at present, "new" dinosaurs are discovered and named at a rate of one every two weeks. Thousands of dinosaurs are now on record, with many of them probably being duplicates of animals already on the books.
Horner, who has two dinosaurs named after him, is proposing that paleontologists follow a rigorous set of procedures known as the Unified Frame of Reference (UFR) when attempting to identify fossils.
The UFR will take into account microscopic analysis of the fossils, which uses technologies not available in the past.
It will also require detailed analysis of where the remains were found, how they appeared when first observed pre-excavation, how they compare to existing species, and more.
"The proposals by Horner are very important as a reminder of a problem paleontologists are aware of, but we still don't know if it will provide a 100 percent watertight solution that means we will never make mistakes about dinosaur species ever again," said Benton.
The study was reported in Science journal.
Tuesday, May 17, 2011
Plankton revived oceans after dinosaur-era extinction
ScienceFair: Plankton revived oceans after dinosaur-era extinction
The revival of the world's oceans after the extinction event that felled the mighty dinosaurs, suggests a study, may rest on the ability of humble plankton to survive a century of seafloor burial. Plankton image from University of Hawaii Institute of Marine Biology
CAPTIONPhoto Collection of Dr. James P. McVey, NOAA Sea Grant Program
Poor old Tyrannosaurus Rex enjoying his apex position at the top of the food chain when ... WHAMMO ... along comes a space rock that blasts a hole in the Gulf of Mexico some 65.5 million years ago.
The impact, "ejected large amounts of material into the atmosphere, blocking sunlight to levels below photosynthesis compensation, and contributing to a global collapse of terrestrial and marine food webs," begins the Nature Communications study led by Sofia Ribeiro of Denmark's University of Copenhagen. Massive earthquakes, tsunamis, ozone depletion, wildfires and a cloudy blackout of the sky lasting perhaps nine months also resulted from the blast, with global cooling that lasted decades as well.
But not every critter fared too badly, the study notes. Deep ocean microbes fared badly for the next three million years. But much less catastrophic extinction rates appear to have afflicted their coastal critter cousins. "In fact, life resurgence in coastal areas appears to have been relatively rapid, possibly occurring in less than a century," says the study.
Why did that happen?
Plankton, says the team, based on an analysis of 450 plankton cysts found in coastal seafloor sediment cores. The team dated the mud in the cores and then attempted to grow the plankton:
We isolated phytoplankton resting stages from sediment cores retrieved from a low-oxygen sill fjord, and found these to be viable for up to 87 ± 12 years ... The growth performance of the tested strains was not affected by nearly a century of dormancy. As this species belongs to a lineage well-established by the Cretaceous, and presumably little affected by the (65.5 million-year-ago) crisis, we argue that resting stages could effectively have contributed to the survival of phytoplankton groups possessing this life-history trait. Our findings indicate that resting stages in coastal sediments may play a significant role for the recovery of primary production after events of global photosynthesis disruption.
Plankton includes bacteria and other microbes, even tiny jellyfish, any type of drifting sea surface critter, basically. But the coastal ones in the study were of the "cyanobacteria" variety, blue-green algae that obtain their energy from photosynthesis. Other types, such as single-celled algae and a variiety seen today in toxic algae blooms, also survive long dormancy.
Some of these same sort of bugs likely first filled the early Earth's skies with oxygen, billions of years ago. And they saved our hash one more time after the impact they wiped out many other creatures some 65.5 million years ago, the researchers conclude. "Germination after long-term dormancy appears to be common."
We, thus, propose that phytoplankton resting stages accumulated in coastal sediments have aided survival across the (extinction event) and played a crucial role for the resurgence of primary production and ecosystem recovery. Phytoplankton resting stage 'banks' in coastal sediments should be incorporated in scenarios aimed at reconstructing or predicting recovery from catastrophes. It should be noted, however, that photosynthesis and biodiversity recovery do not occur at the same rates. Considering that only a fraction of modern phytoplankton groups are able to form resting stages (for example, less than 20% of modern dinoflagellate species are known to produce cysts), removing non-cyst formers at the (extinction event) likely resulted in a larger diversity loss than that inferred from the fossil record (because non-cyst formers do not fossilize). Although the recovery of primary productivity after the (extinction event) was relatively rapid, the recuperation in biodiversity is expected to have been delayed, due to intrinsic limits to how quickly global biodiversity can recover after extinction events.
Fossil found at State Museum confirmed as new dinosaur
ABC27.com: Fossil found at State Museum confirmed as new dinosaur
HARRISBURG, Pa. (WHTM) - Scientists at the Smithsonian Institution have confirmed that a fossil discovered at The State Museum of Pennsylvania is the skull of a previously-unknown dinosaur.
The dinosaur, now known as Daemonosaurus chauliodous, was found in 2004 in a large mudstone block from New Mexico that contained other fossils, museum officials said.
The mudstone block, on loan from the Carnegie Museum of Natural History, was part of a State Museum exhibit that allowed visitors to see a technician working to uncover dinosaur remains.
The specimen was sent back to the Carnegie Museum and eventually the Smithsonian's National Museum of Natural History for additional study. The confirmation findings were announced by the Smithsonian last month.
Daemonosaurus chauliodous roamed the Earth during the Late Triassic period more than 200 million years ago.
Scientists at the Smithsonian said the discovery not only revealed a new species, but also an evolutionary link between two groups of dinosaurs: the early predatory species of the early Late Triassic and later theropods such as the Tyrannosaurus rex.
The name Daemonosaurus is based on the Greek words "daimon," or evil spirit, and "sauros" meaning lizard or reptile. Chauliodus is derived from the Greek word for "buck-toothed" and refers to the dinosaur's big slanted front teeth.
Monday, May 16, 2011
China’s Dinosaur Hunters
China Digital Times: China’s Dinosaur Hunters
At the Guardian, Tania Branigan profiles dinosaur hunter Xu Xing and describes ground-breaking fossil discoveries at digs around China.
Zhucheng’s early Cretaceous relics, Liaoning’s feathered dinosaurs and Xinjiang’s wealth of Jurassic material are among the Chinese treasure troves reshaping our understanding of ancient life on Earth, and the processes that have created the world around us. “Some of the new material from China is breathtaking,” said Dr Paul Barrett, a palaeontologist at the Natural History Museum. “Firstly, the sheer number of new species is impressive. Secondly, some of the dinosaurs that have been discovered have had major impacts on evolutionary debates.”
Local legend in Zhucheng tells of battling black and white dragons: tales rooted, perhaps, in the mighty jaws and femurs found by farmers. For years, residents boiled the “dragon bones” in medicinal soups or ground them into powder.
Excavations began here in the 60s and their pace has dramatically accelerated in recent years as China has poured vast amounts of money into scientific research. More than 50 tonnes of dinosaur fossils have emerged from 30 sites around the town. One remarkable 500-metre-long bone bed has yielded more than 15,000 items. Another site is pitted with 3,000 footprints.
Making sense of it all are dinosaur hunters such as Professor Xu Xing and his colleagues at the Institute of Vertebrate Palaeontology and Palaeoanthropology at the Chinese Academy of Sciences. Xu has identified more than 30 dinosaurs and co-authored papers naming another 20 or so. “I would say I am one of the luckiest people in the world because I have continued finding great species. That makes you even more addicted; it’s like smoking,” he confided.
Accompanying the article is a gallery showing some of the bizarre creatures whose remains have been found in China. (“We did not make these creatures up,” Branigan claims …) The unfamiliarity of the artists’ impressions comes in part from the bright feathers covering most of the dinosaurs, which contrast with the reptilian scales in traditional depictions. These feathers have been a focus of Professor Xu’s work. A post on the Guardian’s “Notes & Theories” science blog from late last year discussed the outdated perception of “naked dinosaurs”:
While walking through a natural history museum gift shop a few years back, I spotted a plush Velociraptor among the piles of dinosauriana. Frankly, it looked pretty stupid. Covered in a soft, fuzzy coat of faux-feathers, it lacked the reptilian menace of the predatory dinosaurs I remembered from my youth. This theropod looked more likely to cuddle someone to death than sink its hyperextendable toe claws into its hapless victim. Surely the feathers were just speculation based on the close relationship between some dinosaurs and birds? Velociraptor never would have looked so silly ….
Some might prefer their favorite dinosaurian predators to have looked just like their depictions in Jurassic Park, but the truth of the matter is that we now know otherwise. In fact, in 2007 it was found that the arms of Velociraptor had little round knobs which would have been anchors for long arm feathers, and the discovery of an early cousin of Tyrannosaurus coated in fuzzy feathers named Dilong [“Emperor Dragon”, one of Professor Xu’s discoveries from Liaoning] means that even the most imposing predator of the Cretaceous may have been covered in feathers during at least part of its life. It is no more fantastic to restore feathers to these dinosaurs or their coelurosarian relatives than it is to depict our hominin ancestors as being covered in hair. It requires an evolutionary perspective to see, but today there is simply no excuse to depict a coelurosaur without feathers.
At the Guardian, Tania Branigan profiles dinosaur hunter Xu Xing and describes ground-breaking fossil discoveries at digs around China.
Zhucheng’s early Cretaceous relics, Liaoning’s feathered dinosaurs and Xinjiang’s wealth of Jurassic material are among the Chinese treasure troves reshaping our understanding of ancient life on Earth, and the processes that have created the world around us. “Some of the new material from China is breathtaking,” said Dr Paul Barrett, a palaeontologist at the Natural History Museum. “Firstly, the sheer number of new species is impressive. Secondly, some of the dinosaurs that have been discovered have had major impacts on evolutionary debates.”
Local legend in Zhucheng tells of battling black and white dragons: tales rooted, perhaps, in the mighty jaws and femurs found by farmers. For years, residents boiled the “dragon bones” in medicinal soups or ground them into powder.
Excavations began here in the 60s and their pace has dramatically accelerated in recent years as China has poured vast amounts of money into scientific research. More than 50 tonnes of dinosaur fossils have emerged from 30 sites around the town. One remarkable 500-metre-long bone bed has yielded more than 15,000 items. Another site is pitted with 3,000 footprints.
Making sense of it all are dinosaur hunters such as Professor Xu Xing and his colleagues at the Institute of Vertebrate Palaeontology and Palaeoanthropology at the Chinese Academy of Sciences. Xu has identified more than 30 dinosaurs and co-authored papers naming another 20 or so. “I would say I am one of the luckiest people in the world because I have continued finding great species. That makes you even more addicted; it’s like smoking,” he confided.
Accompanying the article is a gallery showing some of the bizarre creatures whose remains have been found in China. (“We did not make these creatures up,” Branigan claims …) The unfamiliarity of the artists’ impressions comes in part from the bright feathers covering most of the dinosaurs, which contrast with the reptilian scales in traditional depictions. These feathers have been a focus of Professor Xu’s work. A post on the Guardian’s “Notes & Theories” science blog from late last year discussed the outdated perception of “naked dinosaurs”:
While walking through a natural history museum gift shop a few years back, I spotted a plush Velociraptor among the piles of dinosauriana. Frankly, it looked pretty stupid. Covered in a soft, fuzzy coat of faux-feathers, it lacked the reptilian menace of the predatory dinosaurs I remembered from my youth. This theropod looked more likely to cuddle someone to death than sink its hyperextendable toe claws into its hapless victim. Surely the feathers were just speculation based on the close relationship between some dinosaurs and birds? Velociraptor never would have looked so silly ….
Some might prefer their favorite dinosaurian predators to have looked just like their depictions in Jurassic Park, but the truth of the matter is that we now know otherwise. In fact, in 2007 it was found that the arms of Velociraptor had little round knobs which would have been anchors for long arm feathers, and the discovery of an early cousin of Tyrannosaurus coated in fuzzy feathers named Dilong [“Emperor Dragon”, one of Professor Xu’s discoveries from Liaoning] means that even the most imposing predator of the Cretaceous may have been covered in feathers during at least part of its life. It is no more fantastic to restore feathers to these dinosaurs or their coelurosarian relatives than it is to depict our hominin ancestors as being covered in hair. It requires an evolutionary perspective to see, but today there is simply no excuse to depict a coelurosaur without feathers.
Tiny Tarbosaurus Shows How Tyrants Grew Up
Smithsonian: Dinosaur Tracking: Where Paleontology Meets Pop Culture: Tiny Tarbosaurus Shows How Tyrants Grew Up
In 2006, paleontologists searching the western Gobi Desert under the auspices of the Hayashibara Museum of Natural Sciences–Mongolian Paleontological Center Joint Expedition uncovered a rare fossil prize—the nearly complete skeleton of a juvenile Tarbosaurus bataar. The closest relative to Tyrannosaurus rex, Tarbosaurus was just as big and bad as its North American counterpart, but until now, how this tyrant dinosaur grew up had mostly been inferred from what is known from other dinosaurs. Not only does the new specimen allow paleontologists to better estimate how Tarbosaurus changed as they aged, but it also raises questions about the identity of other young tyrants that have been the focus of long-running debates over dinosaur lives.
For paleontologists Takanobu Tsuihiji, Mahito Watabe and colleagues, the identity of the young Tarbosaurus was fairly easy to determine. Tarbosaurus is the only large tyrannosaur found at the dinosaur-rich Bugin Tsav fossil site, and the only other tyrannosaur found in the same age range between about 70 million and 65 million years ago—Alioramus—was anatomically very different. (Zhuchengtyrannus, another large tyrannosaur found in China and announced last month, came from a different, distant, and slightly older site.) In particular, the new specimen had 13 teeth in the main portion of the upper jaw (the maxilla) paired with 14 and 15 teeth in each side of the lower jaw, which falls within the range of variation seen in adult Tarbosaurus. While this may seem to be a trivial feature, the toothcounts of tyrannosaurs is one of the ways paleontologists distinguish between species and, sometimes, between adults and juveniles of the same species.
In addition to the slenderness of the skull, the large opening for the eye, and other tell-tale features, the juvenile status of the recently discovered Tarbosaurus was confirmed through the microstructure of its leg bones. The observable growth lines inside the leg bones pinned the individual at 2 to 3 years old. This Tarbosaurus was a pre-teen—it perished just before the big growth spurt observed in the growth patterns of North American tyrannosaurs. Furthermore, the nearly complete new specimen is very similar to another partial skeleton given the name “Shanshanosaurus huoyanshanensis” in 1977, which itself is likely to be another Tarbosaurus of a similar age. Thanks to the completeness of the new specimen, another of China’s many enigmatic partial dinosaur skeletons can finally be matched to the proper species.
Curiously, though, the skull of the young Tarbosaurus hints that juvenile tyrants selected from a different menu than the adults. As has been seen among other young tyrannosaurs, the skull of the young Tarbosaurus is relatively shallow and slender, fitted with teeth that are more like knives than serrated railroad spikes as in adults. With these traits, the authors of the new Journal of Vertebrate Paleontology study suggest, juvenile Tarbosaurus was incapable of delivering the heavy crushing bites of the adults and therefore may have specialized on shearing flesh from small prey. Likewise, the young Tarbosaurus had a large ring of bone in its eye—called the sclerotic ring—that would have supported a big eye. Based on a study of how these structures relate to nocturnal activity in dinosaurs, juvenile Tarbosaurus may have hunted in low-light conditions while their parents stalked bigger game during the day or at some other time. If correct, this means that juvenile Tarbosaurus did not compete directly with adults for food in the same habitats—a phenomenon called niche partitioning.
But the new find does more than inform our understanding of Tarbosaurus growth. The new specimen also provides a little more context for at least two ongoing arguments about other tyrannosaur specimens.
Over the past several decades paleontologists have been debating the identity of several dinosaur specimens sometimes said to belong to a genus of “pygmy tyrant” called “Nanotyrannus.” Depending on who you ask, the specimens attributed to this hypothetical genus are either juveniles of Tyrannosaurus or belong to a distinct species, and the new Tarbosaurus has some bearing on this discussion.
Whereas the young Tarbosaurus had the same number of teeth as adult specimens, purported “Nanotyrannus”/juvenile Tyrannosaurus skulls often have several more teeth than adult Tyrannosaurus. A change in tooth shape has been cited as the reason for the difference—as Tyrannosaurus grew up, their teeth became more robust and a few teeth were lost to make room—but the corresponding tooth counts in the closely related Tarbosaurus complicates the picture. The change in tooth counts between the adult and juvenile specimens in Tyrannosaurus may represent a truly unique growth pattern, or may be expressions of variation between individuals rather than changes in growth. (That is, if the “Nanotyrannus” specimens truly are juvenile Tyrannosaurus.) At present, the disparity is something that requires further study of multiple tyrannosaur growth series to resolve.
The second area of debate involves the recently-described tyrannosaur Raptorex. When this dinosaur was described in 2009, it was presented as evidence that many characteristic traits of the largest tyrannosaurs evolved at a small body size. Yet, because of its small size and estimated age of 5 to 6 years old, there is a possibility that the Raptorex specimen is truly the juvenile of another tyrannosaur species. (This idea was broached by a NatureNews article released during last year’s Society of Vertebrate Paleontology meeting, though there was no actual study supporting the hypothesis at the time.) Juvenile dinosaurs often retain archaic traits that cause them to resemble other species that fall out towards the base of their family tree. This makes it difficult to tell the difference between a juvenile and a small adult of a more basal species. Figuring out which category Raptorex belongs in will require more research, though the authors of the new paper report that this other small tyrant specimen was not a juvenile Tarbosaurus (contrary to what was suggested in the NatureNews report). The Tarbosaurus juvenile and the Raptorex specimen differ in at least one major aspect of the hip and several skull characteristics, and this—added to the separation between them in space and time—means that if Raptorex is a juvenile, then it is a juvenile of some other tyrannosaur species.
The new Tarbosaurus juvenile is a truly remarkable specimen. Not only does the skeleton provide paleontologists with a relatively complete look at a moment in the growth of Tarbosaurus, but the bones may also reinvigorate long-running debates about tyrannosaur growth. Young tyrannosaurus were not just miniature copies of adults—the large tyrannosaurus of the late Cretaceous underwent some major changes as they grew—but parsing the fine line between juveniles of giant genera and distinct species of pygmy tyrants remains a contentious area of research.
For more on this new discovery, see the Witmer Lab’s resource-rich website about the new research.
References:
Tsuihiji, T., Watabe, M., Tsogtbaatar, K., Tsubamoto, T., Barsbold, R., Suzuki, S., Lee, A., Ridgely, R., Kawahara, Y., & Witmer, L. (2011). Cranial osteology of a juvenile specimen of Tarbosaurus bataar (Theropoda, Tyrannosauridae) from the Nemegt Formation (Upper Cretaceous) of Bugin Tsav, Mongolia Journal of Vertebrate Paleontology, 31 (3), 497-517 DOI: 10.1080/02724634.2011.557116
Friday, May 13, 2011
Chinese 'dinosaur city' reshapes understanding of prehistoric era
Guardian.co.uk: Chinese 'dinosaur city' reshapes understanding of prehistoric era
It must have been an awe-inspiring sight: four metres tall and weighing 11 tonnes. Its sharp teeth delivered a bone-crushing bite. Yet even "the tyrant from Zhucheng" reached its inevitable, ignominious end. Over time, half its skull was torn from its skeleton and jumbled with the bones of less imposing creatures at this site in what is now China's eastern Shandong province.
Last month – tens of millions of years later – researchers resurrected Zhuchengtyrannus magnus. Impressive though the reconstruction was, it was just one of a succession of fossil discoveries that have put this "dinosaur city" on the map.
Zhucheng's early Cretaceous relics, Liaoning's feathered dinosaurs and Xinjiang's wealth of Jurassic material are among the Chinese treasure troves reshaping our understanding of ancient life on Earth, and the processes that have created the world around us. "Some of the new material from China is breathtaking," said Dr Paul Barrett, a palaeontologist at the Natural History Museum. "Firstly, the sheer number of new species is impressive. Secondly, some of the dinosaurs that have been discovered have had major impacts on evolutionary debates."
Local legend in Zhucheng tells of battling black and white dragons: tales rooted, perhaps, in the mighty jaws and femurs found by farmers. For years, residents boiled the "dragon bones" in medicinal soups or ground them into powder.
Excavations began here in the 60s and their pace has dramatically accelerated in recent years as China has poured vast amounts of money into scientific research. More than 50 tonnes of dinosaur fossils have emerged from 30 sites around the town. One remarkable 500-metre-long bone bed has yielded more than 15,000 items. Another site is pitted with 3,000 footprints.
Making sense of it all are dinosaur hunters such as Professor Xu Xing and his colleagues at the Institute of Vertebrate Palaeontology and Palaeoanthropology at the Chinese Academy of Sciences. Xu has identified more than 30 dinosaurs and co-authored papers naming another 20 or so. "I would say I am one of the luckiest people in the world because I have continued finding great species. That makes you even more addicted; it's like smoking," he confided.
Dr David Hone, of University College Dublin, who worked with Xu for three years and led the Zhuchengtyrannus magnus research, said: "It is a phenomenal achievement, but often it is what he's done [after identification] that is the measure of the real quality of his research." In particular, Xu's work on feathered dinosaurs has shed new light on how the creatures evolved into birds. Xu was "the right person in the right place at the right time", Hone added.
It did not seem that way to Xu for many years. While western peers were modelling Plasticine stegosaurs, he grew up in a remote area of north-western Xinjiang, where education was poor. He had never heard of dinosaurs and hoped to become a physicist – but when he won a rare place at Peking University, he was assigned to palaeontology.
"Even our teacher didn't know what it was, so we thought it must be something very modern. When I found out I was very disappointed," he recalled. It took him years to learn to love his work, but now he enthuses over "beautiful", "amazing" and "bizarre" finds.
"This one might be a new dinosaur – we are trying to confirm," he explained as he compared images of skulls from various species to the squished example facing him in a Shandong museum. Boasting huge, shark-like teeth and a lengthy tail, the creature – discovered in Liaoning province – was unusually large for a feathered dinosaur. It could also, he thought, be relatively primitive.
That specimen was largely intact, but at sites such as Zhucheng's long bone bed, researchers face what Xu calls a "death sandwich". Similar species may be in the same spot; features can be distorted beyond recognition. Deciphering it is like completing multiple jigsaw puzzles – except that many pieces are missing; those that remain are mixed together; and you may or may not have the right pictures to help you. Even new features may not indicate a new species; just a different developmental stage of an existing one.
Those are not the only challenges faced by China's palaeontologists. Regulations on fossil sales and smuggling, introduced over the past decade, have curbed but not halted the trade – hardly surprising when specimens can be worth many times a farmer's annual income. Officials hope an embryonic dinosaur tourism industry will encourage residents to report finds rather than sell them. "Zhucheng's dinosaurs have become world-class stars," said Wang Kebai, the official leading its ambitious tourism projects. People love the mystery of dinosaurs, he said, and the thrill of new discoveries.
Even palaeontology's reluctant recruit admits that studying them for so long has shaped his view of the world.
"These creatures lived millions of years ago; some of them were gigantic," mused Xu. "Examining them, you sometimes feel that humans have a lot of control over nature and other things: but finally, we will all be bones."
Additional research by Han ChengChinese pre-historic discoveriesDr Xu Xing is one of the world's most prodigious paleontologists, working the fertile grounds of China's eastern Shandong province. Among his more striking discoveries are the following:
Microraptor: Found in Liaoning, the tiny four-winged creature from the early Cretaceous probably used its feathered limbs to glide between trees. "Scientifically, it's very important. It provides information revealing a stage we never knew before which is probably very, very important for bird origins."
Limusaurus: "It's not only the first Jurassic therapod dinosaur; it also has a highly reduced first finger." Xu believes it helps to explain how dinosaurs lost their fingers and bird wings evolved. Found in Western China.
Meilong: "A lovely dinosaur, very small. Very rarely do fossils preserve behavioural information, like how the animal slept – this was one of them. It preserves a sleeping posture very similar to modern birds." Dating from the early Cretaceous, it was found in Liaoning.
Incisivosaurus: "It has very bizarre front teeth, a bit like a rabbit." A small, herbivorous theropod – perhaps one metre long – from the early Cretaceous. Found in Liaoning province.
Guanlong: "A very strange primitive tyrannosaur with a huge crest on its head." Found in northern Xinjiang, it dates from the late Jurassic – predating T Rex by around 95 million years.
Gigantoraptor: "Normally, oviraptors are very small. No one expected one with a size comparable to some tyrannosaurs [more than eight metres long], and it has many interesting features." Found in the Gobi desert, it dates to the late Cretaceous era.
Thursday, May 12, 2011
Acanthopholis
Dinosaur Discovery Chronicles: Around 1865 commercial fossil collector John Griffiths found some dinosaurian remains, including osteoderms. In 1867 Huxley named the genus and species Acanthopholis horridus.
Acanthopholis ( meaning "spiny scales") is a genus of ankylosaurian dinosaur in the family Nodosauridae that lived during the Early Cretaceous Period of England.
Around 1865 commercial fossil collector John Griffiths found some dinosaurian remains, including osteoderms, at the shoreline near Folkestone in Kent, which he sold to the metallurgist Dr. John Percy. Percy brought them to the attention of Thomas Henry Huxley, who paid Griffiths to dig up all fossils he could find at the site. Despite being hampered by the fact that it was located between the tidemarks, he managed to uncover several additional bones and parts of the body armour.
In 1867 Huxley named the genus and species Acanthopholis horridus. The dinosaur's generic name refers to its armour, being derived from Greek ακανθα akantha meaning 'spine' or 'thorn' and φόλις pholis meaning 'scale'. The specific name horridus means 'frightening' or 'rough' in Latin. Arthur Smith Woodward emended the species name to Acanthopholis horrida in 1890 because pholis is feminine.
The type specimens, cotypes GSM 109045-GSM 109058, were found in the Cambridge Greensand, a formation itself dating to the Albian to Cenomanian stages around 100 million years ago, but containing reworked material from much older stages. The specimens consist of three teeth, a basicranium, a dorsal vertebra, spikes and scutes.
In 1869 Harry Govier Seeley named several new species of the genus: Acanthopholis macrocercus, based on specimens SMC B55599-55609; Acanthopholis platypus (SMC B55454, SMC B55455-55460); Acanthopholis stereocercus (SMC B5558-55560, B55562, B55566-55568, B55569) and Acanthopholis eucercus (SMC 55551-SMC 55557).
In 1878 Seeley named Acanthopholis tanyspondylus which he would rename Eucercosaurus tanyspondylus in 1879. That same year Seeley split the material of Acanthopholis stereocercus and based a new species of Anoplosaurus on part of it: Anoplosaurus major.
In 1902 however Franz Nopcsa changed it into another species of Acanthopholis: Acanthopholis major. Nopcsa at the same time renamed Anoplosaurus curtonotus into Acanthopholis curtonotus. In 1879 Seeley named the genus Syngonosaurus based on part of the type material of A. macrocercus. In 1956 Friedrich von Huene renamed A. platypus into Macrurosaurus platypus.
In 1999 Xabier Pereda-Superbiola and Paul M. Barrett reviewed all Acanthopholis material. They concluded that all species were nomina dubia: invalid names based on types which were not distinctive beyond being nodosaurid in origin. The bones of the specimens are disarticulated and often fragmentary; of some it is highly doubtful whether they are even ankylosaurian. They also found two previously unpublished names which Seeley had used to label museum specimens: "Acanthopholis hughesii" indicated SMC B55463-55490 and "Acanthopholis keepingi" SMC B55491-55526. Both names were not proposed by them as new species and are nomina nuda.
Acanthopholis's armour consisted of oval keeled plates set almost horizontally into the skin, with long spikes protruding from the neck and shoulder area, along the spine. Acanthopholis was quadrupedal and herbivorous. Its size has been estimated to be in the range of 3 to 5.5 meters (10 to 18 ft) long and approximately 380 kilograms (840 lb) in weight.
Acanthopholis was originally assigned to the Scelidosauridae by Huxley. In 1923 Nopcsa created a separate family Acanthopholidae. Today Acanthopholis is considered a member of the Nodosauridae within the Ankylosauria.
Acanthopholis ( meaning "spiny scales") is a genus of ankylosaurian dinosaur in the family Nodosauridae that lived during the Early Cretaceous Period of England.
Around 1865 commercial fossil collector John Griffiths found some dinosaurian remains, including osteoderms, at the shoreline near Folkestone in Kent, which he sold to the metallurgist Dr. John Percy. Percy brought them to the attention of Thomas Henry Huxley, who paid Griffiths to dig up all fossils he could find at the site. Despite being hampered by the fact that it was located between the tidemarks, he managed to uncover several additional bones and parts of the body armour.
In 1867 Huxley named the genus and species Acanthopholis horridus. The dinosaur's generic name refers to its armour, being derived from Greek ακανθα akantha meaning 'spine' or 'thorn' and φόλις pholis meaning 'scale'. The specific name horridus means 'frightening' or 'rough' in Latin. Arthur Smith Woodward emended the species name to Acanthopholis horrida in 1890 because pholis is feminine.
The type specimens, cotypes GSM 109045-GSM 109058, were found in the Cambridge Greensand, a formation itself dating to the Albian to Cenomanian stages around 100 million years ago, but containing reworked material from much older stages. The specimens consist of three teeth, a basicranium, a dorsal vertebra, spikes and scutes.
In 1869 Harry Govier Seeley named several new species of the genus: Acanthopholis macrocercus, based on specimens SMC B55599-55609; Acanthopholis platypus (SMC B55454, SMC B55455-55460); Acanthopholis stereocercus (SMC B5558-55560, B55562, B55566-55568, B55569) and Acanthopholis eucercus (SMC 55551-SMC 55557).
In 1878 Seeley named Acanthopholis tanyspondylus which he would rename Eucercosaurus tanyspondylus in 1879. That same year Seeley split the material of Acanthopholis stereocercus and based a new species of Anoplosaurus on part of it: Anoplosaurus major.
In 1902 however Franz Nopcsa changed it into another species of Acanthopholis: Acanthopholis major. Nopcsa at the same time renamed Anoplosaurus curtonotus into Acanthopholis curtonotus. In 1879 Seeley named the genus Syngonosaurus based on part of the type material of A. macrocercus. In 1956 Friedrich von Huene renamed A. platypus into Macrurosaurus platypus.
In 1999 Xabier Pereda-Superbiola and Paul M. Barrett reviewed all Acanthopholis material. They concluded that all species were nomina dubia: invalid names based on types which were not distinctive beyond being nodosaurid in origin. The bones of the specimens are disarticulated and often fragmentary; of some it is highly doubtful whether they are even ankylosaurian. They also found two previously unpublished names which Seeley had used to label museum specimens: "Acanthopholis hughesii" indicated SMC B55463-55490 and "Acanthopholis keepingi" SMC B55491-55526. Both names were not proposed by them as new species and are nomina nuda.
Acanthopholis's armour consisted of oval keeled plates set almost horizontally into the skin, with long spikes protruding from the neck and shoulder area, along the spine. Acanthopholis was quadrupedal and herbivorous. Its size has been estimated to be in the range of 3 to 5.5 meters (10 to 18 ft) long and approximately 380 kilograms (840 lb) in weight.
Acanthopholis was originally assigned to the Scelidosauridae by Huxley. In 1923 Nopcsa created a separate family Acanthopholidae. Today Acanthopholis is considered a member of the Nodosauridae within the Ankylosauria.
The sauropod viviparity meme
March 1992 Omni
ScienceBlogs.com: The sauropod viviparity meme
GO TO THE ORIGINAL SITE TO SEE THE ARTWORK THE AUTHOR, DARREN NAISH, REFERENCES IN THE ARTICLE.
Fossils demonstrate beyond any doubt that Mesozoic dinosaurs laid eggs, as of course do all dinosaurs today. But back during the 1960s, 70s and 80s - back when Robert Bakker and his idea about dinosaur biology were regularly featured in magazines and other popular sources - the scientific community was (sarcasm alert) delighted and enthralled by Bakker's proposal of sauropod viviparity.
Yes, mostly forgotten today is the idea that sauropod mothers were once suggested to give birth to a single, live, proportionally large baby, and to then engage in protracted parental care.
While Bakker is typically associated with this idea, it seems to have first been suggested by William Diller Matthew in 1910. Like many other palaeontologists of the time, Matthew assumed (very wrongly) that sauropods were amphibious or aquatic, and it was within this context that he proposed the possibility of sauropod viviparity (Matthew 1910). The thinking here was that viviparity would eliminate the need to lay eggs on land and hence allow a fully aquatic lifestyle. Copious evidence now shows that sauropods were strongly terrestrial - at best being about as 'aquatic' as are rhinos or elephants - and thus Matthew's proposal can be completely ignored.
Bakker's hypothesis was made within the paradigm of sauropod terrestriality. Let's note from the start that there's nothing obviously, inherently 'wrong' with his idea: viviparity, and substantial maternal investment in juvenile body size and parental care have all evolved elsewhere in non-avian reptiles. Nevertheless, the idea that sauropods were K-selected, elephant-style breeders with a very low reproductive turnover is totally at odds with the bulk of our knowledge on dinosaur biology, much of which indicates that dinosaurs were r-selected animals with large clutches, high juvenile mortality and perhaps little to no post-hatching parental care (e.g., Janis & Carrano 1992, Varricchio 2011).
More importantly, the support for the viviparous sauropod hypothesis was always tremendously poor. Three pieces of evidence were mentioned, all circumstantial and/or weak. So far as I can tell, none were put forward or evaluated in the technical literature: a few scant details are provided in Bakker's 1986 book The Dinosaur Heresies but the longest discussion seems to be in Adrian Desmond's 1975 The Hot Blooded Dinosaurs [the cover of the 1975 Blond & Briggs edition is shown here: quite possibly one of the worst dinosaur book covers ever]. Consultation of these sources reveals that the following proposals were used to support the concept of viviparity in sauropods:-
-- Bakker (1986, p. 357) mentioned a supposed 'newborn' Apatosaurus (estimated to weigh c. 230 kg), said to be too big to have hatched from an egg. His scaled diagram of this specimen - from Bakker (1986) - is shown below.
-- The pelvic canal in sauropods looks wide. Maybe, he said, this is because they gave birth to relatively big babies (Bakker 1986, p. 357).
-- Desmond (1975) noted that - due to physical constraints acting on the maximum sizes of shelled eggs - the babies of an oviparous sauropod would be tiny compared to adults. Such tiny animals wouldn't be able to "find their way to the herd", and their size would mean that they surely be crushed underfoot by their gigantic parents. Ergo, relatively big babies, born live in the middle of the herd (a 'reptilian elephant' model), were surely the answer (Desmond 1975, p. 132).
You don't have to be an expert on sauropods, or on dinosaurs or fossil reptiles of any sort, to show that these contentions are problematic. They neither demonstrate nor suggest the presence of viviparity. Let's go through them in turn:-
-- On the existence of the 'newborn': how do we know it's a 'newborn'? We don't. Other sauropod babies (read on) are substantially smaller than c. 230 kg, so it seems more parsimonious to assume that the c. 230 kg juvenile had been growing for some unknown postnatal period.
-- On the wide pelvic canal, this could be present because sauropods have really wide pelves (for reasons unconnected to the production of eggs and/or babies), and I'm not sure that sauropods do have particularly wide pelvic canals when compared with other oviparous reptiles anyway.
-- Finally, the behavioural scenario discussed by Desmond (1975) is entirely speculative and relies on the assumption that sauropod babies required 'herd protection'. We actually have good reason to think that baby sauropods (and other baby dinosaurs too) lived independently of adults (e.g., Varricchio 2011).
Another possible objection to the concept of sauropod viviparity is that archosaurs are unable to evolve this parturition strategy (Hopson 1977). That is, some people have argued that archosaurs are incapable of evolving viviparity: it's been said that developing archosaur embryos rely on the eggshell as a calcium reservoir and cannot therefore dispense with it (Hopson 1977, Packard et al. 1977, Tarsitano 1982), and also that limited oxygen exchange in the archosaur uterus prevents extended embryonic development (Andrews & Mathies 2000). Indeed, we don't know of any confirmed cases of viviparity in archosaurs, though its possible presence has been suggested at times for hesperornithine birds, metriorhynchoid crocodilians, pachycephalosaurian ornithischians and pterosaurs.
The definitive killer point on the whole viviparous sauropod idea comes from the discovery of numerous definitive sauropod eggs and embryos. It's true that many Cretaceous eggs traditionally identified as those of sauropods* have never been shown beyond doubt to belong to these dinosaurs, but there are now many, many others. At Auca Mahuevo in Argentina, "over a dozen in situ eggs and nearly 40 egg fragments encasing embryonic material were recovered" (Chiappe et al. 1998, p. 258). Six more Auca Mahuevo eggs - this time revealing well-preserved, near-complete skulls - were published a few years later (Chiappe et al. 2001, Salgado et al. 2005) [embryonic Auca Mahuevo sauropod skulls shown here, from Chiappe et al. (2001)]. More recently, sauropod hatchlings discovered right next to hatched and unhatched eggs (oh, and preserved with the large snake Sanajeh indicus as well) have been reported from the Upper Cretaceous of India (Wilson et al. 2010) (the snake was evidently preying on the babies).
* The French 'Hypselosaurus eggs' are the best case.
These eggs and embryos do only belong to one sauropod group (Titanosauria), but we also have eggs and embryos from close relatives of sauropods (e.g., Reisz et al. 2005) and from elsewhere in Saurischia and Dinosauria. The principle of parsimony demands that egg-laying must be assumed for all sauropods in the absence of compelling evidence to the contrary.
What drew me to write about this topic in the first place is the artwork. The best known picture depicting sauropod viviparity is Doug Henderson's painting - shown here - where a mother Apatosaurus is craning her neck round to look at her newborn baby. Unfortunately, what you see here is cropped. In the full-size version (which I don't seem to have anywhere*), what appears to be afterbirth is obviously present next to the baby (here, you can just see part of it overlapping the baby's tail). Incidentally, can you spot the technical error in the illustration? I mean, besides the brand new, just-born baby and all that. Yes, if you've spent years staring at the back ends of reptiles you'll note that the mother sauropod has been given a transverse cloacal slit, as if it's a squamate. In keeping with crocodilians, it should really have been given a longitudinally aligned slit.
The other painting - quite probably inspired by, or based on, Henderson's - is by John Bindon and appeared in a children's book called Dinosaur Mysteries (1989, Hamlyn), written by Mary O'Neill. It's shown here. The human is meant to be Robert Bakker.
Ok, so, I'm only aware of two relevant illustrations, but I always find it interesting when a minority scientific opinion becomes encapsulated in an illustration (other examples: non-avian theropods climbing trees, ceratopsians with frills embedded within their neck musculature). As others have noted, this can sometimes have the effect of 'reinforcing' a hypothesis - of making it look more plausible, or more widely accepted than it is, especially if the art is good. In reality, it's just art.
On that note, while you might think that the idea of sauropod viviparity is dead and now well off the radar, it kinda lives on. I say this because several artistic reconstructions - and a particularly well known North American museum mount - show an adult (presumably female) sauropod guarding or in some way interacting with a single, well-cared-for baby. Most viewers are going to assume from such works that sauropods exhibited elephant-like reproductive behaviour. Viviparity might not be assumed by a naïve observer, but it might. I would, anyway, go as far as saying that such reconstructions (which - don't get me wrong - I like very much) are flat-out misleading, and inaccurate. Even supposing that sauropods did practise extensive post-hatching parental care (note that there's no evidence for this), we know that they produced big clutches, so a dutiful parent wouldn't be looking after a single baby. Well, not unless all the other babies had been eaten.
And, yes, this whole article is indeed a spin-off of one brief aside in the April 1st mokele-mbembe article. I am amused to see that some cryptozoologists who support the existence of the mokele-mbembe are aware of the viviparity hypothesis and suggest that mokele-mbembe likely practises this behaviour too. Meh.
Wednesday, May 11, 2011
Triassic Crocodile Cousin Walked Like a Dinosaur
ScienceMag.org: Triassic Crocodile Cousin Walked Like a Dinosaur
At a glance, it would be tempting to call Poposaurus gracilis a dinosaur. This 225-million-year-old reptile stood on two legs, had small forelimbs, and sported a long, tapering tail that allowed it to balance while walking and running about the Late Triassic landscape. But Poposaurus wasn’t a dinosaur at all. It was much more closely related to the forerunners of crocodiles, and, according to a new study, its curious mode of walking challenges a leading hypothesis about why dinosaurs were so successful.
First described over a century ago, Poposaurus is a “rauisuchian,” part of an extinct lineage of reptiles whose diverse array of members included the precursors of crocodiles and their closest relatives. Rauisuchians differed from crocodiles as we know them today in holding their limbs upright beneath their bodies rather than out to the side. This arrangement made them more efficient at walking and running on land, and, until recently, all rauisuchians were thought to have walked on all fours.
Then in 2006, paleontologists Sterling Nesbitt and Mark Norell of the American Museum of Natural History in New York City described a bipedal rauisuchian they called Effigia okeeffeae. The discovery showed that at least some of the rauisuchians adapted a very dinosaurlike posture. Now, a new skeleton of Poposaurus described by Nesbitt, Yale University paleontologist Jacques Gauthier, and co-authors in the current edition of the Bulletin of the Peabody Museum of Natural History confirms that it, too, walked like a dinosaur. Instead of being an evolutionary fluke, the new find suggests that Effigia was part of a specialized subgroup of bipedal crocodile cousins that diversified at the same time as the early dinosaurs.
The newly described Poposaurus was found in the Triassic Chinle Formation of southern Utah’s Grand Staircase-Escalante National Monument. The fossil included most of the postcranial skeleton from midway down the neck to the tip of the tail, stretching about 4.5 meters in all. According to the new research, the anatomy of the creature’s pelvis and hind limbs shows that Poposaurus walked upright, planting its feet close to the midline of its body. In fact, the hip anatomy would have made it impossible for Poposaurus to sprawl its limbs out to the side, like living crocodiles, although the exact way the rauisuchian’s feet touched the ground is unclear. Poposaurus may have stood on tiptoe, walked with the whole foot touching the ground, or it might have alternated between both foot postures depending on how fast it was moving.
Discoveries of bipedal crocodile cousins such as Effigia and Poposaurus have also raised questions about how dinosaurs rose to dominance near the end of the Triassic. Paleontologists such as Robert Bakker, curator of the Houston Museum of Natural Science in Texas, had previously credited the upright, bipedal posture of the dinosaurs for their success over the variety of crocodile relatives that flourished during the Triassic. By holding their limbs directly beneath their bodies, the argument went, dinosaurs would have moved faster and more efficiently than the cousins of crocodiles and relatives of early mammals that also lived at the time. The subgroup of rauisuchians that includes Poposaurus independently evolved the same posture—and competed with early dinosaurs such as Coelophysis in the same environments—but why they perished while dinosaurs thrived is a mystery.
“This new specimen is important because it is so complete,” says Randall Irmis, curator of paleontology at the Utah Museum of Natural History at the University of Utah in Salt Lake City, who found the skeleton in 2003 but was not involved in the new study. In addition to finally illustrating what the body of Poposaurus looked like, he says, the newly described specimen “helps us understand that transition to bipedality” among the rauisuchians. Whereas Effigia had a toothless beak, Irmis points out, Poposaurus had sharp, recurved teeth and was clearly a carnivore like other rauisuchians, “so it shows poposauroids became bipedal before they evolved an herbivorous habit.”
At a glance, it would be tempting to call Poposaurus gracilis a dinosaur. This 225-million-year-old reptile stood on two legs, had small forelimbs, and sported a long, tapering tail that allowed it to balance while walking and running about the Late Triassic landscape. But Poposaurus wasn’t a dinosaur at all. It was much more closely related to the forerunners of crocodiles, and, according to a new study, its curious mode of walking challenges a leading hypothesis about why dinosaurs were so successful.
First described over a century ago, Poposaurus is a “rauisuchian,” part of an extinct lineage of reptiles whose diverse array of members included the precursors of crocodiles and their closest relatives. Rauisuchians differed from crocodiles as we know them today in holding their limbs upright beneath their bodies rather than out to the side. This arrangement made them more efficient at walking and running on land, and, until recently, all rauisuchians were thought to have walked on all fours.
Then in 2006, paleontologists Sterling Nesbitt and Mark Norell of the American Museum of Natural History in New York City described a bipedal rauisuchian they called Effigia okeeffeae. The discovery showed that at least some of the rauisuchians adapted a very dinosaurlike posture. Now, a new skeleton of Poposaurus described by Nesbitt, Yale University paleontologist Jacques Gauthier, and co-authors in the current edition of the Bulletin of the Peabody Museum of Natural History confirms that it, too, walked like a dinosaur. Instead of being an evolutionary fluke, the new find suggests that Effigia was part of a specialized subgroup of bipedal crocodile cousins that diversified at the same time as the early dinosaurs.
The newly described Poposaurus was found in the Triassic Chinle Formation of southern Utah’s Grand Staircase-Escalante National Monument. The fossil included most of the postcranial skeleton from midway down the neck to the tip of the tail, stretching about 4.5 meters in all. According to the new research, the anatomy of the creature’s pelvis and hind limbs shows that Poposaurus walked upright, planting its feet close to the midline of its body. In fact, the hip anatomy would have made it impossible for Poposaurus to sprawl its limbs out to the side, like living crocodiles, although the exact way the rauisuchian’s feet touched the ground is unclear. Poposaurus may have stood on tiptoe, walked with the whole foot touching the ground, or it might have alternated between both foot postures depending on how fast it was moving.
Discoveries of bipedal crocodile cousins such as Effigia and Poposaurus have also raised questions about how dinosaurs rose to dominance near the end of the Triassic. Paleontologists such as Robert Bakker, curator of the Houston Museum of Natural Science in Texas, had previously credited the upright, bipedal posture of the dinosaurs for their success over the variety of crocodile relatives that flourished during the Triassic. By holding their limbs directly beneath their bodies, the argument went, dinosaurs would have moved faster and more efficiently than the cousins of crocodiles and relatives of early mammals that also lived at the time. The subgroup of rauisuchians that includes Poposaurus independently evolved the same posture—and competed with early dinosaurs such as Coelophysis in the same environments—but why they perished while dinosaurs thrived is a mystery.
“This new specimen is important because it is so complete,” says Randall Irmis, curator of paleontology at the Utah Museum of Natural History at the University of Utah in Salt Lake City, who found the skeleton in 2003 but was not involved in the new study. In addition to finally illustrating what the body of Poposaurus looked like, he says, the newly described specimen “helps us understand that transition to bipedality” among the rauisuchians. Whereas Effigia had a toothless beak, Irmis points out, Poposaurus had sharp, recurved teeth and was clearly a carnivore like other rauisuchians, “so it shows poposauroids became bipedal before they evolved an herbivorous habit.”
Subscribe to:
Posts (Atom)