The first fossil tracks belonging to large, carnivorous dinosaurs discovered in Victoria, Australia show that large dinosaurs were living in a polar environment during the Cretaceous Period, when Australia was still joined to Antarctica and close to the South Pole.
The find is being reported today, Friday, Oct. 19, at the Society of Vertebrate Paleontology meeting in Austin, Texas, by Anthony Martin, senior lecturer in environmental studies at Emory. Martin researched the find with Patricia Vickers-Rich and Lesley Kool of Monash University and Thomas Rich of the Museum of Victoria.
The three separate dinosaur tracks are about 14 inches long, show at least two or three partial toes, and were likely made by large carnivorous dinosaurs (theropods) on river floodplains about 115 million years ago during the Cretaceous Period. Based on track sizes, Martin estimates that these dinosaurs were 4.6 to 4.9 feet tall at the hip, large by human standards but about 20 percent smaller than Allosaurus, a large theropod from the Jurassic Period.
Martin found two of the tracks during a February 2006 visit with Rich to the "Dinosaur Dreaming" site, near the coastal town of Inverloch. Tyler Lamb, a Monash undergraduate student and volunteer at the dig site, found a third track in February 2007, having been alerted by Kool to look for them. Martin then confirmed its identity during a visit in July 2007. Other possible, partial dinosaur tracks have been found at the same site and another locality, but these have yet to be studied in detail.
Vickers-Rich and Rich have been studying the dinosaurs and mammals of Victoria for nearly 30 years. Lower Cretaceous strata of Victoria have yielded a sizeable amount of dinosaur skeletal material since the late 1970s, resulting in the best-documented polar dinosaur assemblage in the world. Until Martin's find in 2006, however, only one dinosaur track (from a small herbivorous dinosaur) had been documented.
"I think a lot more tracks are out there, but they've been too subtle to notice before now," Martin says. He and the other researchers say they are optimistic that additional tracks will be found, now that they have examples of the tracks to go by in their searches.
- Emory University