July 14, 2010
Fossil Proves Local Existence Of Giant Flightless Bird
Fifty million years ago, when what is now Washington state was covered with a verdant subtropical rainforest, a 380-pound flightless bird called Diatryma stalked the floodplains of the region's meandering rivers.
Although Diatryma was long thought to have existed in this region, a recent discovery by geologists from Western Washington University of a fossilized footprint of this 7-foot-tall bird proves that it did indeed roam the forests of the Pacific Northwest, said George Mustoe, a paleontologist at WWU. In fact, the track is the world's only known track of any giant extinct bird.
"Discovery of this amazing foot track is the first undoubted evidence that these birds existed here," said Mustoe. "It's quite a find."
The track, which measures almost a foot in length, was found in the Chuckanut Formation east of Bellingham last summer. WWU faculty had been in the area investigating a landslide on land owned by the state Department of Natural Resources when the fossil was discovered by Mustoe and Keith Kemplin, of Bellingham, according to WWU geologist Dave Tucker.
The 1,300-pound sandstone slab which holds the Diatryma track was helicoptered to a nearby road and transported to WWU, where it will go on display in the University's Geology Department. The slab also holds a number of smaller bird footprints; one may be from an ancient ancestor to the heron, others are smaller shorebirds.
The newly found foot track sheds further light on the life of this giant. Diatryma is popularly portrayed as a ferocious predator, chasing down and devouring small mammals, including small ancestors of horses. However, there is only circumstantial scientific evidence for this interpretation. The huge bird may have used its obviously strong beak to crush tough leaves, and giantism in flightless birds is much more commonly associated with a vegetarian diet. The track shows that this bird had only small stubby triangular claws on its toes, rather than the grasping talons typical of carnivorous birds that are often shown in artists' representations of the beast.
Controversy has previously surrounded this extinct giant bird in the Northwest, and was the center of much media attention. A large footprint found in the Green River near Auburn in 1992 was reported to be the track of Diatryma. Some paleontologists initially accepted the Green River track, which is also on display at WWU, as authentic "“ but others considered it to be a pseudofossil or other artifact. The new Whatcom County find bears very little resemblance to the 1992 track, and casts further doubt on its authenticity.
Diatryma thrived during the Eocene epoch, about 10 million years after the extinction of the dinosaurs. Nearly complete skeletons of Diatryma have been found in Wyoming, New Mexico, and Europe, but the Chuckanut track is the only evidence of the giant flightless bird on the West Coast of North America.
Image Caption: Sketch of Diatryma, from fossil records, courtesy WWU
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