Call that bird 'Sir.' (paleontology)

Call that bird 'Sir'

Imagine a 7-foot-tall flightless bird with a head larger than the one atop a polar bear. Over 50 million years, ago, such an animal actually walked the Earth. Called Diatryma, this fowl has long puzzled paleontologists, who wonder in particular what such a large, heavy bird ate for dinner. While one new study supports the mainstream view that Diatryma consumed animal flesh, a different analysis suggests it dined mostly on plants.

Lawrence M. Witmer and Kenneth D. Rose of Johns Hopkins University School of Medicine in Baltimore, along with Thomas M. Bown of the U.S. Geological Survey in Denver, performed a biochemical analysis of the Diatryma jaw, focusing on a recently discovered lower jaw found in the Bighorn Basin of northwest Wyoming. The fused junction between the right and left bones of the lower jaw was especialy strong for a bird, notes Witmer. He and his colleagues conclude that the strong bones could have withstood large biting forces generated by well-developed jaw muscles--which are evident from marks on the bone where the muscle attached.

The researchers think the Diatryma could cut through flesh and even possibly crush bone. They suggest the bird either scavenged carcasses or caught live prey. "This thing was huge. It had a head a foot and a half long. It could eat anything it wanted," says Witmer. Its possible meal choices included tiny horses the size of house cats and primitive lemurs and tapirs that have been found in the same deposits as Diatryma.

Allison V. Andors of the American Museum of Natural History in New York City reaches the opposite conclusion in his study. Although he thinks Diatryma may have occasionally supped on animal flesh, Andors says several pieces of evidence suggest the huge bird primarily ate leafy plant matter--a particularly rare diet among birds.

Andors notes Diatryma shares several features in common with existing herbivorous birds, many of which are also large and flightless. The plant-eating Takahe in New Zealand, for instance, has a stout neck and legs as well as an oversized beak, features all present in Diatryma. Moreover, the upper jaw of Diatryma does not hook downward to a sharp point as do the jaws of many birds that tear flesh. Andors, who could not attend the meeting, published an abstract in the Sept. 28 JOURNAL OF VERTEBRATE PALEONTOLOGY.