Science rewrites assumptions about pre-historic animals

From the Edmonton Journal: Science rewrites assumptions about pre-historic animals
Paleontologists borrow medical diagnostic tools to rebuild dinosaurs

DINOSAUR PROVINCIAL PARK - Paleontologist Phil Currie was walking along the sandstone cliffs of the badlands in southern Alberta when he spotted something sticking out of the side of the hill.

It appeared to be the fossil of an ancient turtle. But as he began to clear away the sand, he could see that it was the skull of a dinosaur.

There is nothing extraordinary about finding fossils in Dinosaur Provincial Park. In fact, there is no better place to find the remains of these so-called “terrible lizards” that walked the earth for more than 165 million years.

But in the days that followed in that summer of 2010, Currie suspected he may have found something extraordinary indeed. This specimen appeared to be so rare and so exquisitely preserved that he instructed his students and colleagues to go slow with the excavation when he had to leave base camp for a few days.

“I just didn’t want to miss out on this one,” he recalls. “It’s extremely rare to find a dinosaur such as this, and almost as rare to find one that is so complete. I wanted to be there to see what we had by the time we were done with it.”

Currie likes to say that building a dinosaur from fossils found in sand or embedded in rock is both an art and a science. Having a skull and a nearly complete skeleton such as this one, which he plans to reveal to the public in a year or two, makes it relatively simple.

It’s far more common for paleontologists to find a carcass that has been scattered, scavenged or partially swept away by a flood before it fossilized. In many cases, the bones are mineralized or deformed and sometimes crushed.

As a result, art and imagination often trumped science when it came to building models from scattered bones that were found in the past.

In the first recorded reference to a dinosaur, British naturalist Robert Plot mistook the thigh bones that formed the knee of a Meglosaurus for those of an elephant brought to England by the Romans. Nearly a century later, Richard Brookes examined the same specimen and concluded they were the fossilized testicles of a giant man who lived in Biblical times — between the creation of Earth and the flood that destroyed all life except for that which survived on Noah’s Ark.

He named it “Scrotum humanum.”

Constrained by religion, scientists in his day couldn’t even contemplate the notion that enormous creatures might have lived on Earth more than 65-million years ago, before an asteroid plowed into the planet and triggered their rapid extinction.

Thanks to Charles Darwin and others, a handful of 19th century geologists finally recognized fossilized elements as those of giant extinct animals.

But the assumption that they were cold-blooded lizards, dull-witted, slow moving and not particularly well-suited to their environment prevented many scientists from accepting the possibility that contemporary birds might be related to a group of maniraptoran theropods, or that tyrannosaurs might have been highly social, warm-blooded creatures that hunted in packs.

The situation has changed dramatically. Since the early 1990s, a new wave of fossil discoveries and the use of powerful tools, such as CT scans, X-rays and engineering software, has provided paleontologists with sophisticated ways of testing those early evolutionary ideas.

Now, thanks to a mathematical simulation done by Currie and Nathan P. Myhrvold of Microsoft Research, we know, for instance, that the enormous tail of Apatosaurus was not so much a way of counterbalancing this dinosaur’s long neck, as it was a giant whip that could theoretically break the speed of sound and create a sonic boom that would scare the heck out of a large predator, or at least make it take pause.

We also know from research done by Currie and his team that some tyrannosaurs experienced rapid growth spurts at fairly advanced stages of their lives, and this may have led some scientists to misidentify young animals as different species.

“Science is not only allowing us to rewrite the history of dinosaurs, science and new fossil discoveries are giving us the data that is needed to add several new chapters,” says Currie, who has authored several books.

Currie’s collection of students and colleagues in the field of science reflects this cutting edge approach to paleontology.

PhD student Lisa Buckley, for example, is an avid birder who is also curator of collections at the Peace Region Paleontology Research Centre in British Columbia.

In the contemporary world of avian science, biologists look at plumage, songs and behaviour to separate and identify closely related and morphologically similar bird species.

“If you take away those attributes, and strip the specimen down to its bare bones, would they come to the same conclusions?” she wondered when she joined Currie’s team.

It’s an important question in the world of paleontology because contemporary birds are closely related to some dinosaurs.

Buckley hopes to use her results as a guide to determine what paleontologists might be missing when they don’t have the data to determine colour, sound and behaviour of the dinosaurs they have identified and studied.

“It is possible that one skeleton of a bird, or small theropod, for example, might represent multiple species that would distinguish among themselves using colour, audio cues and behaviour,” she says.

Victoria Arbour, on the other hand, is much more of a techno-geek about her research.

She uses CT scanning data, shape-building computer software and other engineering tools to determine whether tail clubs, such as those in the family of armoured dinosaurs that includes Ankylosaurus, could be used as weapons, as some scientists have speculated.

In one experiment that was published in a scientific journal recently, Arbour concluded that a large tail club could generate between 364 and 718 megapascals of impact stress, which may not have been enough to kill a T-rex, she says, but it could certainly break its ankle, for instance.

One of the problems that Arbour is confronting is how to identify which dinosaurs had the big tail club and which ones had the small one. Tail clubs are rarely found with the rest of the dinosaur skeleton, so it’s hard to know with certainty whether a small one came from a young dinosaur or from a different species altogether.

That’s where Michael Burns comes in. The PhD student studies the microstructure of dinosaur bones and armour to determine whether an animal is young or fully grown. Fortunately for him, bone tissue is often layered, analogous to tree rings in that it records the growth of the animal.

“In the past,” says Burns, “scientists would often look at a metre-long bone, for example, and assume that it must have come from an adult. But we know that some dinosaurs have much larger bones than that. So it’s very possible that this long bone they were looking at actually came from a juvenile that had a lot more growing to do.”

What distinguishes Currie’s team from those in other North American universities is that the youngest members are routinely getting their research results published in peer-reviewed papers and seeing or hearing their names printed or broadcast in the media.

Part of it is has to do with the never ending allure of the subject, but a lot of it has to do with the science.

Scott Persons got pretty good at it since he appeared on CBC’s Quirks and Quarks, the venerable radio show that tracks the best breaking science stories in the world. But he still makes fun of the fact that his investigation of the posteriors of theropods has left his family lamenting that he hadn’t picked a different research topic, such as researching the origin of birds.

It has, however, given him a pretty good story to tell about how the enormous tail of T-rex and other tyrannosaurs was much more than one end of a see-saw that balanced the predator’s huge head so that it wouldn’t fall flat on its face.

The first step in his research was to cut into the tail of a caiman, a South American crocodile, which is anatomically similar to T-rex and other tyrannosaurs. To his surprise, he discovered that a single muscle — the caudofemoralis — which is attached to the upper leg by a long tendon, is responsible for the pull that helps drives the crocodile’s locomotion.

Persons then looked at theropods such as T-rex to see if they had a similar muscle that might have also have given them added “forward thrust.”

“I was surprised when I did the computer simulations,” he says. “I expected to find the caudofemoralis of Tyrannosaurs rex to be comparable to what you would find in a modern crocodile. As it turned out, it wasn’t as big as that of a modern croc, it was bigger, much bigger than I imagined. That’s because a T-rex has a different setup in its tail that allowed for the formation of a super-sized muscle.

“When you think about it,” he says, noting that an Albertosaursus might be able to run at speeds of up to 50 kilometres per hour, “it makes sense. T-rex was a large predatory animal that needed to be able to move fast in order to catch its prey. It would not have been successful if it was as slow moving and clumsy as paleontologists once thought.”

As much as new technologies and computer programs are key to understanding what dinosaurs looked like, how fast they grew and moved and how they interacted with each other, there is no getting past the down and dirty ways that technician Clive Coy routinely gets into in the first stages of building a dinosaur.

He’s the one that puts the fossil in plaster after it’s dug out of the field site. When he carefully removes the plaster jacket back in the lab at the University of Alberta, he may use glue and a steel frame to stabilize it.

“That’s when the fun begins,” he says.

Using what is essentially a miniature jack hammer or a hand tool with a tungsten carbide bit, Coy carefully cuts away the rock, dirt and sediment that is embedded in every crack and orifice of the fossil, much in the same way dentists do when they prepare a tooth for a filling.

Only in Coy’s case, it can take a year or two to get the job done.

“It’s not a job for people who don’t have patience,” he says. “My day can be measured by the centimetres or inches that I have scraped off a fossil. For me, it’s a form of meditation. For others, it can be hell.”

Given all that has changed in the world of paleontology in the past two decades, what with the blood vessels that scientist Mary Schweitzer found in a dinosaur five years ago and the development of new tools that can detect colours of some dinosaurs, Currie is convinced that the book of paleontology will have a lot more revisions and new chapters in the next decade.

“You know, thirty years ago, it was almost unfathomable to think that we would some day extract soft tissue from dinosaurs as Mary Schweitzer did. Now the talk is about recovering DNA from dinosaurs. I used to be a skeptic, but given how the game is changing so dramatically, I wouldn’t bet against it. Very little in the field of paleontology is written in stone.”

Phil Currie and Eva Koppelhus are always looking for volunteers to work in their lab at the University of Alberta, if you think have what it takes to work on fossils. Young and old are welcome. Eva would love to hear from you. Send her an email at ebk@ualberta.ca