Abrictosaurus

Dinosaur Discovery Chronicles: The holotype specimen was discovered in Lesotho and consists of a partial skull and skeleton (UCL B54). Paleontologist Richard Thulborn, who first described the specimen in 1974, considered it a new species of Lycorhinus and named it L. consors, using the Latin word consors which means 'companion' or 'spouse'.


Abrictosaurus (ih-BRICK-tuh-SAW-russ) Abrictosaurus ("wakeful lizard") is a genus of heterodontosaurid dinosaur from the Early Jurassic Period of what is now southern Africa. It was a small bipedal herbivore or omnivore, approximately 1.2 meters (4 feet) long, and weighing less than 45 kilograms (100 pounds).

This dinosaur is known from the fossil remains of only two individuals, found in the Upper Elliot Formation of Qacha's Nek District in Lesotho and Cape Province in South Africa, respectively. The Upper Elliot is thought to date from the Hettangian and Sinemurian stages of the Early Jurassic Period, approximately 200 to 190 million years ago.

This formation is thought to preserve sand dunes as well as seasonal floodplains, in a semiarid environment with sporadic rainfall. Other dinosaurs found in this formation include the theropod Megapnosaurus, the sauropodomorph Massospondylus, as well as other heterodontosaurids like Heterodontosaurus and Lycorhinus. Remains of terrestrial crocodylomorphs, cynodonts and early mammals are also abundant.

Description
Heterodontosaurids like Abrictosaurus were small, early ornithischians, named for their markedly heterodont dentition. They are best-known for the large, canine-like tusks (often called caniniforms) in both upper and lower jaws. There were no teeth in the front of the jaws, where a hard beak was used to crop vegetation. There were three premaxillary teeth, with the first two small and conical and the third enlarged to form the upper caniniform, counterpart to the even larger lower caniniform, which was the first dentary tooth. In the upper jaw, a large gap (or diastema) accommodated the lower caniniform tooth and separated the premaxillary teeth from the wider chewing teeth of the maxilla. Similar teeth lined the remainder of the lower jaw.

Abrictosaurus is usually considered the most basal member of the family Heterodontosauridae. Lycorhinus and Heterodontosaurus both had high-crowned cheek teeth, which overlapped each other in the jaw, forming a continuous chewing surface analogous to those of Cretaceous hadrosaurids. Abrictosaurus had more widely-separated cheek teeth, with lower crowns, more similar to other early ornithischians. It has been suggested that Abrictosaurus lacked tusks and that this is another primitive feature.

However, caniniforms were clearly present on one of the two specimens of Abrictosaurus. The upper caniniform measured 10.5 millimeters (0.4 inches) high, while the lower reached 17 mm (0.67 in). These caniniforms were serrated only on the anterior surface, unlike those of Lycorhinus and Heterodontosaurus, which were serrated on both anterior and posterior edges. Abrictosaurus also had smaller, less powerful forelimbs than Heterodontosaurus and one fewer phalanx bone in both the fourth and fifth digits of the forelimb.

History and naming
Both specimens of Abrictosaurus are housed in the collection of University College London. The holotype specimen was discovered in Lesotho and consists of a partial skull and skeleton (UCL B54). Paleontologist Richard Thulborn, who first described the specimen in 1974, considered it a new species of Lycorhinus and named it L. consors, using the Latin word consors which means 'companion' or 'spouse'. As UCL B54 lacked the caniniforms which had been found in the type species, Lycohinus angustidens, Thulborn believed it to be female.

Neither the skull nor the skeletons of Abrictosaurus have been fully described in the literature. A tooth from the latest Triassic of Switzerland has been assigned to Abrictosaurus sp., but this has not been supported, as the specimen does not have unique characteristics of Abrictosaurus, heterodontosaurids, or ornithischians in general.

In 1975, James Hopson redescribed a fragmentary heterodontosaur skull (UCL A100) found in South Africa that Thulborn had previously assigned to Lycorhinus angustidens. After showing that UCL A100 could not belong to L. angustidens but was instead more similar to UCL B54, Hopson erected a new genus to contain both specimens. The generic name Abrictosaurus (from the Greek αβρικτος/abriktos meaning 'wakeful' and σαυρος/sauros meaning 'lizard') refers to Hopson's disagreement with Thulborn's hypothesis that heterodontosaurids underwent periods of aestivation (hibernation during hot and/or dry seasons). The specific name was retained, creating the new binomial Abrictosaurus consors.

Despite Hopson's renaming, Thulborn continued to consider Lycorhinus angustidens, Heterodontosaurus tucki, and Abrictosaurus consors to be three species of the genus Lycorhinus. Most paleontologists maintain all three genera separately, although there is no precise definition of a species or genus in paleontology.

Sexual dimorphism
The hypothesis of sexual dimorphism in heterodontosaurids has long centered on Abrictosaurus. Tusks are a sexually dimorphic trait in many modern mammals, including musk deer, walrus, Asian elephants and many pigs, with tusks being present primarily in males. The lack of tusks in UCL B54 led to suggestions that it was female; perhaps even a female of another species.

The discovery of caniniforms in UCL A100 showed that A. consors also has this 'male' characteristic, suggesting that it is at least a valid species in its own right. However, UCL B54 may actually be a juvenile, based on its short face and unfused sacral (hip) vertebrae. Therefore, the lack of tusks could be a juvenile trait instead of a secondary sexual characteristic, weakening the case for sexual dimorphism.

Young tyrannosaurs were careful predators: scientists

The Hindu: Young tyrannosaurs were careful predators: scientists
Their parents may have wielded their massive strength and size to kill large prey, but young tyrannosaurs were careful predators who relied on quickness and agility rather than raw power, scientists have found.

Tyrannosaurs were the largest ever known dinosaurs that roamed the earth some 65 million years ago.

An international team of scientists who investigated the youngest and most complete skull of a 70-million—year-old tyrannosaur, unearthed five years ago in the Gobi Desert in Mongolia, believe the young animals were not powerful like their parents and fed on smaller preys.

The skull was found as part of a nearly complete skeleton, missing only the neck and two-thirds of the tail, which belonged to a Tarbosaurus, a fearsome predator roughly as large as its closest known relative, Tyrannosaurs rex.

“We knew that adult Tarbosaurus were a lot like T rex,” researcher Takanobu Tsuihiji, of the National Museum of Nature and Science in Tokyo, was quoted as saying by LiveScience.

Based on careful analysis of the microstructure of the leg bones, researchers estimated this predator was only 2 to 3 years old when it died.

It was about 9 feet long, about 3 feet high at the hip and weighed about 32 kg. In comparison, an adult Tarbosaurus was 35 to 40 feet long, 15 feet high, weighed about 6 tons and probably had a life expectancy of about 25 years.

CAT scans of the immature 11.4-inch skull revealed that it was far more delicate than an adult’s and was incapable of handling the kinds of twisting and stress that the reinforced skull of a grown-up Tarbosaurus could.

“Adults show features throughout the skull associated with a powerful bite — large muscle attachments, bony buttresses, specialised teeth,” Tsuihiji explained.

In comparison, “the juvenile is so young that it doesn’t really have any of these features yet, and so it must have been feeding quite differently.”

This suggests “the younger animals would have taken smaller prey that they could subdue without risking damage to their skulls,” Tsuihiji explained.

“This spectacular specimen provides us with a really clear window into how these dinosaurs changed over the course of their lives,” Witmer told LiveScience.

“Tarbosaurus is found in the same rocks as giant dinosaurs like the long-necked sauropod Opisthocoelicaudia and the duckbill hadrosaur Saurolophus,” said researcher Mahito Watabe of the Hayashibara Museum of Natural Sciences in Okayama, who led the expedition that uncovered the new skull.

“But the young juvenile Tarbosaurus would have hunted smaller prey, perhaps something like the bony-headed dinosaur Prenocephale.”

This range of feeding strategies could have been one of the secrets of success for tyrannosaurs, strengthening their role as the dominant predators during their time, Witmer said.

The scientists detailed their findings in the Journal of Vertebrate Paleontology.

Dinosaurs A to Z: Abelisaurus

Dinosaur Discovery Chronicles: Both genus and species of Abelisaurus were named and described by Argentine paleontologists Jose Bonaparte and Fernando Novas in 1985.

Fossil skull

Artists reproduction

Abelisaurus ("Abel's lizard") is a genus of abelisaurid theropod dinosaur from the Late Cretaceous Period (Campanian) of what is now South America. It was a bipedal carnivore that probably reached 7 to 9 meters (25 to 30 feet) in length, although it is known from only one partial skull.

The generic name recognizes Roberto Abel as the discoverer of the specimen and former director of the provincial Museum of Cipolletti in Argentina, where the specimen is housed. It also incorporates the Greek sauros, meaning 'lizard'. There is one named species, A. comahuensis, which honors the Comahue region of Argentina, where the fossil was found. Both genus and species were named and described by Argentine paleontologists Jose Bonaparte and Fernando Novas in 1985, who placed it in the newly-created family Abelisauridae.

Classification
Many other abelisaurids have since been discovered, including extremely complete specimens of Aucasaurus, Carnotaurus and Majungasaurus. Some scientists place Abelisaurus as a basal abelisaurid, outside the subfamily Carnotaurinae. Others are less certain of its position. Abelisaurids share some skull features with the unrelated carcharodontosaurids and, since Abelisaurus is known only from a skull, future discoveries may show that this genus was in fact a carcharodontosaurid. However, this is thought unlikely.

Fossil material
The one known fossil skull of Abelisaurus is incomplete, especially on the right side. It is also missing most of the palate (roof of the mouth). Despite the missing pieces, it is over 85 centimeters (33 inches) long. Although there are no bony crests or horns, like those found in some other abelisaurids, such as Carnotaurus, rough ridges on the snout and above the eyes might have supported some kind of crest made out of keratin, which would not have become fossilized. There are also very large fenestrae (window-like openings) in the skull, which are found in many dinosaurs and reduce skull weight.

Disputed age
Abelisaurus is one of the many dinosaurs that have been discovered in Patagonia. It was originally described as coming from the Allen Formation but subsequent research proved the remains were actually found in the older Anacleto Formation (part of the Neuquén Group) of Rio Negro Province, Argentina. The Anacleto is a geologic formation in South America, dating from the early Campanian stage of the Late Cretaceous Period, between 83 and 80 million years ago.

Bibliography:
From Wikipedia

Australia: Outback town claims 'dinosaur capital' title

ABC News: Outback town claims 'dinosaur capital' title
An outback Queensland town has begun promoting itself as Australia's 'dinosaur capital'.

Several large dinosaurs have been discovered at Winton, north-west of Longreach, dating back 98 million years.

The Lark Quarry outside of Winton is currently the only recorded site of a dinosaur stampede in the world.

Winton shire tourism manager Craig Templeman says logos are still being finalised but the aim is to promote the destination for tourists keen on the dinosaur theme.

"Our new branding for the region will be 'Winton - the Dinosaur Capital of Australia', which we are hoping will attract more of that education, school group market, science groups and of course young families, mums and dads with the kids, who are really keen on those big monsters that were around 95 to 98 million years ... [ago]," he said.

"The six biggest dinosaur skeletons in the world have been found here.

"The Lark Quarry footprints or trackways are the only location in the world where you can see a stampeding footprint of a big carnivore sauropod and the kids love that sort of thing."

Bringing Dinosaurs Up to Speed

Smithsonian.com: Dinosaur Tracking - where paleontology meets pop culture: Bringing Dinosaurs Up to Speed
Dinosaurs are ambassadors of paleontology. Much to the frustration of scientists who study plants, invertebrates, and even fossil mammals, the word “paleontologist” is closely associated with the image of scruffy researchers digging around for dinosaur bones. Despite the popularity of dinosaurs, though, our ability to understand what they can tell us about how evolution works has been limited by the relative scarcity of skeletons. Finding a single skeleton of one species is just the very beginning of unraveling the mystery of how that creature evolved and how it fits into our understanding of ancient life.

Paleontologist John Bell Hatcher understood this. In 1901 Hatcher wrote a paper on the Jurassic dinosaurs found near Cañon City, Colorado, and he prefaced his summary with a few remarks on the study of dinosaurs:

Notwithstanding the great wealth of certain of our Mezozoic horizons in dinosaurian remains and the exceptional vigor with which the bringing together and study of dinosaur bones have been pursued for the last quarter of a century in this country by Marsh, Cope, Baur, Osborn, Williston and others, and for an even longer period, though under much less favorable conditions, by British and European paleontologists, yet we are still ignorant of the complete osteology of all but a few of the many proposed genera of dinosaurs, while of the phylogeny of the various genera and species of the different families we know absolutely nothing. This is the more remarkable considering the progress that has been made in mammalian paleontology, where in many families, as for instance the horses, camels, and titanotheres, nearly every step in their development has been traced and can be pointed out with as much precision as can the different stages in the perfection of the modern steam engine, electric motor, or other mechanical device wherein the forces of nature have been made to serve the uses of man.

Why did this disparity exist? The problem was not “a lack of interest in dinosaur remains as such,” Hatcher wrote, but due to “the vastly greater difficulties encountered in bringing together sufficiently complete collections from the various localities and horizons to permit of a comparative study of the different forms from each.” In other words, paleontologists had not yet systematically sampled and compared bones from particular localities to get a refined picture of how dinosaurs changed over time. The rush to obtain the biggest and best specimens, as well as the time required to exhume those bones, kept scientists from taking a closer look at the tempo and mode of dinosaur evolution. The fossil deposits in the vicinity of Cañon City seemed to have the most potential for outlining the history of dinosaurs from the Triassic through the Cretaceous, and so Hatcher reviewed them in the hopes out drawing out some clues about dinosaur evolution.

One hundred and ten years later, we know quite a bit more than Hatcher did about dinosaurs and their relationships. In the past decade, especially, a more refined picture of dinosaur evolution has emerged, though not everything has been solved. The study of dinosaurs is not restricted to the American West, but is now a worldwide endeavor, and new species are constantly adding to our understanding of dinosaur evolution. Still, there is much basic work that remains to be done in terms of understanding how individuals of dinosaur species varied from one another and investigating the natural history of particular dinosaur species. Dinosaur science has never been as lively or vibrant as it is now, but our understanding of their lives and evolution will continue to change.

Western Australia: Fears gas hub will harm dinosaur prints

ABC.net.au: Fears gas hub will harm dinosaur prints
EMILY BOURKE: To Western Australia now and traditional owners around Broome will vote tomorrow on whether to accept the latest deal on a proposed multi-billion dollar gas plant.

Woodside and its joint venture partners want to bring gas from the offshore Browse Basin to James Price Point.

Woodside and the WA Government have offered native title claim groups $1.5 billion in benefits over several decades.

But palaeontologists are worried about the destruction of dinosaur footprints known as underprints if the project goes ahead.

David Weber reports.

DAVID WEBER: Indigenous people in the area are split.

In general terms the Jabirr Jabirr support the proposed plant and the Goolarabooloo don't.

The Premier Colin Barnett is hoping the deal will be approved.

COLIN BARNETT: Essentially the details have been agreed between the Aboriginal negotiators, the Kimberley Land Council, the State Government and Woodside. That now needs to go back to the traditional owners at a broader open meeting and I'm hopeful that they will agree and endorse this project.

DAVID WEBER: Palaeontologists fear that important evidence of dinosaurs will be lost if the gas plant is built at James Price Point.

There are sauropod underprints in the area.

An underprint is the impression of a footprint which has degraded over time.

Dr Steve Salisbury of the University of Queensland:

STEVE SALISBURY: The prints up in the Kimberley are by far the best record that we have of dinosaurs in the western part of Australia.

They're the only record for a number of dinosaurs in Western Australia and many of the prints represent groups that we have no other evidence for within Australia.

So in that context not only within Western Australia but then for Australia they are very significant.

DAVID WEBER: Could the gas hub that's proposed for James Price Point pose any threat to the prints?

STEVE SALISBURY: Definitely prints will be destroyed if the gas hub goes ahead but then there are obviously indirect effects of just opening that area up to this development.

With all the proposed dredging, the jetties and things that are going to go ahead, that's definitely going to affect the longshore movement of sand up and down the Dampier coast. And many of the best prints along that stretch of coastline may end up being covered by sand.

DAVID WEBER: A report for the State Government has played down the significance of the underprints saying there are better examples elsewhere in the Kimberley region.

There will be further studies before any construction takes place but there seems to be an acceptance that the prints will be destroyed if they're not removed.

Dr Salisbury:

STEVE SALISBURY: I mean there's nowhere in the world where you can go and look at the movements of 15 different types of dinosaurs along a stretch of coast that's 80 kilometres long. I mean it's phenomenal in terms of the sort of information we get out of it for understanding dinosaur movements.

DAVID WEBER: Dr Salisbury says he and other palaeontologists are making an appeal to the Federal Environment Minister, Tony Burke.

EMILY BOURKE: David Weber.

A 1980s Look at Smithsonian Dinosaurs

Smithsonian.com: A 1980s Look at Smithsonian Dinosaurs

by Brian Switek
I thought that I had seen just about every major dinosaur documentary from the 1980s, but I just found out that I missed at least one: the Smithsonian Video Collection’s Dinosaurs. It was one of many programs—like A&E’s miniseries Dinosaur!—that were inspired by deep changes to what we thought dinosaurs were like, and the show acts as a snapshot of a vibrant time in paleontology just before Jurassic Park kicked dinomania into full gear.

Narrated by James Whitmore, Dinosaurs was a typical look into the science of bringing dinosaurs back to life. There were no computer-generated dinosaurs to be found. Instead, paleoart old and new was mixed in with interviews of paleontologists to give viewers a general understanding of dinosaurs. The show was the video equivalent of the innumerable books on dinosaurs that I pored over as a kid.

Dinosaurs followed the standard documentary format of its time. After briefly mentioning the pop-culture appeal of dinosaurs, the show proceeded through a number of video chapters that touch on the great “Bone Wars” of the late 19th century, how fieldwork is almost the same today as it was a century ago, and how paleontologists reconstruct dinosaur anatomy, before touching on the debate over dinosaur extinction. All pretty standard stuff, but what makes it worth another look is that it contains interviews with a few Smithsonian paleontologists rarely seen in other programs.

During the time Dinosaurs was created, paleontologists were fiercely debating the physiology of dinosaurs. Did dinosaurs maintain high, constant body temperatures and have active metabolisms like birds and mammals? Or did they have lower metabolic rates and variable body temperatures, like crocodiles? Even though most paleontologists agreed on the new image of agile, dynamic dinosaurs, the actual physiology of dinosaurs remained hotly debated, and Dinosaurs featured a unique head-to-head argument between Robert Bakker—the primary advocate of “hot-blooded” dinosaurs—and Smithsonian curator Nicholas Hotton. The two scientists did not actually debate each other on camera, but Hotton was given the chance to respond to each of the lines of evidence Bakker proposed. My favorite moment is when Bakker argues that the rapid rate of dinosaur evolution is evidence for bird-like physiology, and Hotton incredulously responds, “for cryin’ out loud, that’s the silliest argument I’ve ever heard!”

Hotton passed away in 1999, but some of the other Smithsonian paleontologists are still at the National Museum of Natural History. Early in the show we meet Hans-Dieter Sues, the current curator of vertebrate paleontology, and in a later segment current collections manager Michael Brett-Surman takes viewers on a tour through the maze of cabinets containing most of the Smithsonian’s dinosaurs. Together the paleontologists explain the historical importance of the Smithsonian collections and the way scientists are finding new ways to look at old bones. Even though much of Dinosaurs will be familiar to dedicated dinosaur fans, the peeks behind the scenes at the Smithsonian are a treat.