Anthony Martin, paleontologist at Emory University in Atlanta, GA recently discovered two fossilized footprints presumably made by a landing bird during the Early Cretaceous period at Dinosaur Cove in Victoria, Australia. This discovery marks the oldest known bird tracks in Australia.
Dinosaur Cove is located on the southeastern side of the continent near the Great Otway National Park and was created during the Cretaceous period. Much of the rocky coastal strata of Dinosaur Cove were formed in river valleys in a polar climate during the Early Cretaceous. A great rift valley formed as the ancient supercontinent Gondwana broke up and Australia separated from Antarctica. As the flood plain that sank, sand, mud and silt deposits blanketed the plants and animal remains compressing it to rock.
"These tracks are evidence that we had sizeable, flying birds living alongside other kinds of dinosaurs on these polar, river floodplains, about 105 million years ago," Martin says.
Martin believes the thin-toed tracks in fluvial sandstone were likely made by two individual birds roughly the size of an egret or small heron. The tracks were identified as avian, as opposed to a non-avian theropod because of the rear-pointing toes.
A long drag mark on one of the tracks gave additional insight. "I immediately knew what it was — a flight landing track — because I've seen many similar tracks made by egrets and herons on the sandy beaches of Georgia," Martin says.
The ancient landing track from Australia "has a beautiful skid mark from the back toe dragging in the sand, likely caused as the bird was flapping its wings and coming in for a soft landing," Martin says. Fossils of landing tracks are rare, he adds, and could add to our understanding of the evolution of flight.
Today's birds are actually modern-day dinosaurs, and share many characteristics with non-avian dinosaurs that went extinct, such as nesting and burrowing. (Martin previously discovered the trace fossils of non-avian dinosaur burrows, including at a site along the coast of Victoria.)
The journal Paleaontology is publishing an analysis of this study which is co-authored by Patricia Vickers-Rich and Michael Hall of Monash University in Victoria and Thomas Rich of the Museum Victoria in Melbourne.
Read more at Emory University eScience Commons.
Drawing by Tony Martin.