College of Arts and Sciences
WIU Paleobiologist on New Dinosaur Discovery Team; Paper in Proceedings of the Royal Society B
November 11, 2009
MACOMB, IL - - A new dinosaur discovered in South Africa - - named Aardonyx, meaning "earth claw" - - is shedding light on the origins of the biggest dinosaurs ever, the sauropods, said Matthew Bonnan, Ph.D., associate professor of biology at Western Illinois University who is part of the discovery team.
With funding from National Geographic Society's Committee for Research and Exploration, and with support from Western Illinois' College of Arts and Sciences and Center for Innovation in Teaching and Research, Bonnan has been to Free State, South Africa three times (2004, 2006, 2007) working with South African colleagues at two quarry sites determined to be Early Jurassic, approximately 195 million years ago.
The discovery was accepted for publication in the Proceedings of the Royal Society B, a significant journal of biological research and reviews, with the title, "A new transitional sauropodomorph dinosaur from the Early Jurassic of South Africa and the evolution of sauropod feeding and quadrupedalism."
"I can't express in words just how exciting and what a privilege this is to announce to the world a brand new dinosaur; one that's a transitional, that tells us in some ways how we moved from smaller biped animals to bigger, heavier quadruped animals," Bonnan said.
"And it fits in so well with the research I'm doing personally, and with students.
"On a scientific level, it's really fulfilling to have a hypothesis on how you think dinosaurs got large, then to test that in the field and get back these kind of data - - a new dinosaur - - that really does start to fill in some of those anatomical gaps," he added.
An analysis of the bone microstructure of the 7-meter (20-feet) long herbivore indicates that it was young and still growing. Its skeletal anatomy shares a number of key features with sauropods. Limb proportions show that Aardonyx (r DON icks) was a biped, although its forearm bones interlock - - like those of quadrupedal sauropods - - suggesting that it could occasionally walk on all-fours, Bonnan explained.
Bonnan's specialties in the digs are as a functional morphologist, who understands anatomy and how bones and muscles work together in movement, and as a vertebrate paleobiologist, who studies how vertebrate animals have evolved. Co-researchers include primary investigator Adam Yates, Ph.D. (paleontologist), Bernard Price Institute for Palaeontological Research, University of the Witwatersrand, Johannesburg, South Africa; Johann Neveling, Ph.D. (geologist), Council for Geoscience, Pretoria, South Africa; Marc Blackbeard, a master's degree student at the University of the Witwatersrand, who discovered the first bones of Aardonyx and helped excavate and map the site; and Anusuya Chinsamy, Ph.D., (paleontologist) of the University of Cape Town, South Africa, who specializes in histology - - examining thin-sections of bone in living and fossil vertebrates for clues to their growth.
"We were ecstatic that when we began to take bone bits on the surface away and dig a little deeper, we got nice, well-preserved solid bones. Incredibly, not only were we finding pieces of the limbs and the ribs and the backbone, but we also started to find pieces of the skull. That's when it started to get really exciting, because the skull can tell you if you have a new dinosaur or not," Bonnan said. "By the end of 2006 we had enough of the skull to get an idea of what this animal looked like."
The skull and jaws show signs that this dinosaur had a wide gape and could bulk-browse, taking in huge mouthfuls of vegetation in each bite, an adaptation amplified later in sauropod dinosaurs. Despite its "small" size, sauropod-like vertebral joints had developed to brace its back bone, and the thigh bone (femur) was straightened for weight-support, Bonnan added. The feet were flattened, bore large claws, and were more robust medially, features of a weight-bearing axis shifted towards the midline as in their giant near-descendants.
He said the next step was to take the bones back to the lab in South Africa and clean them, assemble them and start to figure out whether what they had unearthed was something new to science or whether it was already known and maybe just a bigger form.
"It got really exciting in 2007 when we started laying these bones out and looking closely at the features on them," Bonnan said. "We realized this animal, while it shared certain features with ones that we know, had features that we've never seen before. We finally were able to say this is indeed a new species of dinosaur. That was an incredible feeling."
The two bones in the forearm of the new dinosaur Aardonyx was the tipoff to Bonnan that this animal was related to the giant sauropods.
"The forearm bones of Aardonyx are beginning to show the interlocking position found in the giant sauropods. In other dinosaurs that are bipeds, that walk on their hind legs, you don't see that feature. You only see that in sauropods," Bonnan explained. "Aardonyx may not have walked on all fours all the time, but it was certainly was capable of dropping down and walking on those forearms because it had the ability to resist the stress."
"Both on a scientific level and a personal level this has just been absolutely fantastic," Bonnan added.
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