UNC professor, students piece together model of prehistoric reptile

UNC professor and students piece together a model of an 11-foot prehistoric reptile

CorrespondentAugust 19, 2012 

Alison the rauisuchian was a reptile to be reckoned with in her day, the Late Triassic, and in her neighborhood – the spot in supercontinent Pangea that became southern Durham County.

She weighed nearly a ton, and she and her fellow rauisuchians prowled at the top of the food chain until they disappeared at the end of the Triassic, to be succeeded by dinosaurs.

She’s no small shakes in the annals of North Carolina fossil-dom, either. Since her discovery in a Durham County brick quarry by two UNC-Chapel Hill students in 1994, she’s been hailed as one of the state’s most important finds.

She’s the first rauisuchian (“raw ih SOO kee un”) found in eastern North America, though there have been others in the U.S. West and elsewhere. She’s the only one of her particular species ever found.

Dr. Hans-Dieter Sues, Smithsonian Institution senior scientist and curator of vertebrate paleontology, helped with early research carried out by Dr. Joseph G. Carter, paleontology professor in UNC-Chapel Hill’s Department of Geological Sciences.

The rauisuchian’s discovery, along with its captured prey, “provided unexpected new insights into Late Triassic life in what is now eastern North America,” Sues says.

At work in the lab

Now, some of Carter’s students are finishing the first complete rendition of Alison in polyurethane, readying her for a broad public debut. It’s expected to be finished during the fall semester and hopefully will go on display within this next year, perhaps at the N.C. Museum of Natural Sciences in Raleigh. The actual bones are already there, under lock and key.

Though there’s no way to determine sex, in scientific parlance, she’s Portosuchus (genus) alisonae (species), named by students for the late Alison L. Chambers, their companion on many a paleontology field trip.

To students bending her ribs and putting her tailbone together like a jigsaw puzzle, she’s just plain Alison.

Student Maria Connolly asked the assembled heads bent over the polyurethane skeleton one recent morning if they knew why Alison is so trim.

It’s her metabolism, Connolly cracks. She’s dead!

That’s not all, chimes in Carter, a transplanted Kansan who echoes the Coroner’s pronouncement on the Wicked Witch in “The Wizard of Oz.”

“Not only merely dead,” he quotes. “But really most sincerely dead.”

Two-hundred-and-twenty-one million years dead, give or take 5 million.

Ah, but when she was alive! She wore armor plates on her neck, back and breast, was about 11 feet long, and likely stood upright at least part of the time.

A nickname for a rauisuchian is “bear croc” – it looks like a crocodile, prowls like a bear. Though they’re not ancestors of the dinosaur, Carter says, “It was Nature’s first attempt to build a dinosaur-like predator.”

Head uplifted, massive jaws open, eye sockets unseeing, she looms above her builders. On a table nearby, her yet-unattached hands are lifted in an unintended but touching gesture of supplication.

Previous students did an incomplete reconstruction in 2000; it substituted painted Plexiglas for the bones missing when Alison was unearthed. After a campus showing, this first replica was relegated to the lab while Carter and students researched Alison’s rauisuchian relatives and used their findings to create the missing parts .

A determination to keep Alison in North Carolina led Carter to take on the arduous task of overseeing her reassembly 18 years ago, even though his specialty is invertebrates. (He’s currently coordinator of an international effort to create the most complete family tree ever assembled for bivalves – clams, oysters, and the like.)

But no way, he says, was he going to send Alison out-of-state. “This is part of North Carolina’s heritage.”

Had her bones left, she’d be as unknown to most North Carolinians as the state’s other big vertebrate fossil find – a Late Triassic crocodile-like creature, a rutiodon, found in the 1800s in Durham County. It’s in the American Museum of Natural History in New York.

Quarry discovery

Alison came to light when Carter student Brian Coffey and roommate Marco Brewer spotted some bone chips, then an anklebone, as they hiked the quarry. They felt that this was something big, and when they hauled the anklebone in to Carter, he agreed.

“When I saw it, I thought it must be another rutiodon,” he says.

A large part of the class went back to the quarry, and subsequently found part of the skull, a couple of teeth, the entire neck, most of the shoulders, two arms complete with hands, the collarbone, breastplate, part of the hip, part of the back, most of both legs including the feet, part of the tail, and many ribs.

“It was one of the most complete rauisuchians ever discovered,” says Carter. And it was articulated – the bones positioned just as they’d been in life.

The crab-like hand with a locked-together thumb and forefinger ending in a sharp claw meant that they had stumbled upon an entirely new species.

The creature was found lying in what was once a lake, on top of captured prey. The spenosuchian crocodylomorph beneath her “looked like an alligator in its head, long skinny legs like a greyhound,” Carter says. Subsequently researched by the Smithsonian’s Sues, it was yet another new species, grallator, this one of the genus Dromicosuchus.

Not only that, Alison’s stomach area contained remains of four other small Triassic creatures, one of which, Carter says, was “second, second, second cousin” to a reptile thought to be an ancestor of mammals.

Carter theorizes that having killed its dinner, the rauisuchian was trying to drag it out of the lake when it got stuck in the mud and died.

To test his cause-of-death theory, he tried to walk in the similar sediment of nearby Jordan Lake when the water was low. “I tried to see how sticky it was. If you got both legs stuck in there, you’re in deep trouble.”

‘Show and tell’

Carter wears Hawaiian shirts to class, has a poster of Indiana Jones in his office and, like his students, appreciates but is not overwhelmed by their weighty task. Teaching paleontology, he says, “is like having ‘show and tell’ every day.”

“It’s just fun to talk about new discoveries. People have an inherent desire to know about the world they live in.”

Usually, he says, reconstructing a major fossil find is undertaken only by experts in museums. But Alison’s promise of being “a really marvelous teaching tool” prompted him to break tradition and involve undergraduates, even his freshman-seminar students planning to study English, philosophy and the like.

Other experts like Sues and Dr. Paul E. Olsen of Columbia University joined in the research and subsequent paper-writing, as did graduate students Karen Peyer and Stephanie E. Novak.

But it was undergraduates who hauled Alison’s skeleton, surrounded by petrified mud, out of the quarry in chunks. “It’s like these bones were encased in concrete,” Carter says.

Some of them, compressed by millions of years’ worth of sand, fell into pieces. “You have to know where they were, and then glue them back together again.”

Sure, the 300 students who’ve worked on Alison have made some mistakes, he says in a later conversation. “Just like today,” when a rib being bent broke instead.

“Sometimes, you’ve got to break a bone to build a skeleton,” he says.

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