September 20, 2011
Study Finds ‘Clear Evidence’ Meteorite Wiped Out Primitive Birds
The same meteorite impact that caused dinosaurs to go extinct 65 million years ago also essentially wiped out ancient birds, a team of paleontologists claim in a new study.
The researchers, led by Nicholas Longrich of Yale University, studied collections of approximately two dozen bird fossils of various species from the school's Peabody Museum of Natural History, as well as from the American Museum of Natural History, the University of California Museum of Paleontology, and the Royal Saskatchewan Museum.
According to a Yale press release, Longrich and colleagues discovered "clear evidence that many primitive bird species survived right up until the time of the meteorite impact" by identifying and dating the Cretaceous fossils, including many which were from birds that had been alive "within 300,000 years of the impact."
Their findings have been published in the September 19 issues of the journal Proceedings of the National Academy of Sciences (PNAS).
"This proves that these species went extinct very abruptly, in terms of geological time scales," Longrich said in a statement.
"The birds that had been discovered hadn't really been studied in a rigorous way," he added. "We took a much more detailed look at the relationships between these bones and these birds than anyone had done before."
In the press release, Longrich said that bird fossils from the era are rare because of how light and fragile they are, and how easily they are damaged or carried away by water.
He believes that only a small fraction of the species from the Cretaceous survived the Chicxulub meteorite impact, going on to evolve over time into the modern-day avian species.
"The birds he examined showed much more diversity than had yet been seen in birds from the late Cretaceous, ranging in size from that of a starling up to a small goose. Some had long beaks full of teeth," the university's statement said. "Yet modern birds are very different from those that existed during the late Cretaceous."
For example, Longrich says, modern birds have far more specialized features, including those of the penguin, the hummingbird, and the flamingo. Archaic birds, on the other hand, "would have occupied a narrower range of ecological niches," officials from Yale added.
"The basic bird design was in place, but all of the specialized features developed after the mass extinction, when birds sort of re-evolved with all the diversity they display today," he said. "It's similar to what happened with mammals after the age of the dinosaurs."
While his study is not the first to suggest that these primitive avian species were wiped out at the same time as the dinosaurs, dying out suddenly instead of gradually, "this new evidence effectively closes the book on the debate," Longrich claims.
Image 2: The bones are from the 17 species of Cretaceous birds which went extinct around the time of the dinosaurs. The two on the far left are foot bones and the rest are shoulder bones. Credit: Courtesy Yale University
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