Word: fossils
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Dates: during 1980-1989
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...birds was a pigeon-size creature that looked like a dinosaur with feathers. Now, however, the 150 million-year-old Archaeopteryx has apparently been dethroned by a specimen named Protoavis ("first bird"), which lived 75 million years before Archaeopteryx. Last week's announcement was based on two fragmentary fossil skeletons found in the arid badlands of western Texas in 1984 by Texas Tech University Paleontologist Sankar Chatterjee. They suggest that Protoavis was a contemporary of the earliest dinosaurs. "If the identification is correct," says Yale Paleobiologist John Ostrom, who has examined the crow-size remains, "it has to send...
...avian wishbone and cloak of feathers, led many scientists to hail it as a missing link between reptiles and birds. But Protoavis has even more birdlike features than its younger cousin, Chatterjee believes. While both species have wishbones and forelimbs elongated into wings, he points out, the older fossil also has a bird's wide eye sockets, a large braincase and a breastbone designed to anchor muscles used in flight. Tiny bumps along Protoavis' forelimbs could indicate where feathers were attached. Explains Chatterjee: "Because some birds in the Cretaceous period (which began about 130 million years ago) were very modern...
Last summer Walker, a professor at the Johns Hopkins University medical school, was looking for baboon fossils, when he spotted the skull fragment. By studying volcanic ash and other bones nearby, his colleagues determined the skull's age. Its pedigree was trickier. It has the structure of a late australopithecine: wide palate, huge rear molars, enormous cheekbones and a pronounced crest of bone running along the top of the skull. But other features -- a for- ward-thrusting muzzle, an orangutan-size brain and an apelike jaw structure -- are primitive. Leakey believes this mosaic suggests, as he has argued for years...
...fossil record had also apparently shown that the australopithecines evolved in an orderly way: first came afarensis, followed by africanus, then robustus and boisei. But the age and form of WT 17000 convinced Leakey and Walker that the lineage was not simple after all. Boisei did not descend from robustus, and probably not even from afarensis...
...anthropologist at the City University of New York's Lehman College. "Relationships among australopithecines will need to be somewhat revised." That will not surprise anthropologists. Although the current diagram of humanity's family tree is based on thousands of specimens, most of them are frustratingly incomplete. Walker's fossil may force a revision in the textbooks, but it is not likely to be the last...