Last period of global warming
The Victoria fossils are about 110 million years old, around the time that Australia split with Antarctica, and dinosaurs roamed in prolonged polar darkness along forested southern Australia river plains. It was one of the last times the Earth experienced global warming, with an average temperature of 68 degrees Fahrenheit – about 10 degrees higher than today.
During the polar winter, though, the temperature could plunge below freezing. Previously, researchers theorized that the small dinosaurs in the region survived harsh weather by sheltering beneath large tree roots or in hollows. Martin's find, however, indicates that they may have dug into the soft banks of rivers flowing out of the rift valley.
The age, size and shape of the likely burrows led Martin to hypothesize that they were made by small ornithopod dinosaurs – herbivores that were prevalent in the region. These ornithopods stood upright on their hind legs and were about the size of a large, modern-day iguana.
"It's fascinating to find evidence connecting a type of behavior between dinosaurs that are probably unrelated, and lived in different hemispheres during different times," Martin says. "It fills in another gap in our understanding of the evolution of dinosaurs, and ways they may have survived extreme environments."
An eye for subtle clues
A specialist in trace fossils – including tracks, scat and burrows – Martin is known for detecting subtle paleontology clues. He also identified the first tracks of a large, carnivorous dinosaur in Victoria, and the first fossil crayfish burrows from the same area.
Martin teaches a seminar at Emory on modern-day animal tracking, a skill that he says aids him in finding signs of prehistoric life. "It's important to do as much field work as possible, because it gives your mind a better library of search images," he says.
Evidence of dinosaur burrows discovered in Australia comes on the heels of a similar finding in Montana, suggesting burrowing behaviors were shared by dinosaurs of different species, in different hemispheres, and spanned millions of years during the Cretaceous Period -- even in harsh polar environments.
"This research helps us to better understand long-term geologic change, and how organisms may have adapted as the Earth has undergone periods of global cooling and warming," says paleontologist Anthony Martin, a senior lecturer in environmental studies at Emory University and a research associate at Monash University in Melbourne, who discovered the Australian burrows.
(Photo Credit: Carol Clark and Anthony Martin, Emory University)
Evidence of dinosaur burrows discovered in Australia comes on the heels of a similar finding in Montana, suggesting burrowing behaviors were shared by dinosaurs of different species, in different hemispheres, and spanned millions of years during the Cretaceous Period -- even in harsh polar environments.
"This research helps us to better understand long-term geologic change, and how organisms may have adapted as the Earth has undergone periods of global cooling and warming," says paleontologist Anthony Martin, a senior lecturer in environmental studies at Emory University who discovered the Australian burrows.
(Photo Credit: Drawing by James Hays, Fernbank Museum)
Source: Emory University