Paleontology and Evolution in the News

摘要

It may come as a surprise to you that the raptor-like Archaeopteryx, usually considered to be the first bird, is actually a lot less bird-like than scientists had believed. In a press release from Florida State University (www.fsu.edu/ news/2009/10/09/first.bird) reporting on the study by Gregory M. Erickson, paleobiologist of Florida State University, the image of Archaeopteryx as the iconic first bird living 150 million years ago in the Late Jurassic Period in what is now Germany has been recast as more of a feathered dinosaur. That's because new, microscopic images of the ancient cells and blood vessels inside the bones of the winged, feathered, claw-handed creature showed unexpectedly slow growth and maturation that took years, similar to that found in dinosaurs, from which birds evolved. In contrast, living birds grow more rapidly and mature in a matter of weeks. Dr. Erickson said, "From these findings, we see that the physiological and metabolic transition into true birds occurred millions of years after Archaeopteryx. But perhaps equally important, we've shown that avians were able to fly even with dinosaur physiology." The study is published in the Oct. 9, 2009, issue of the journal PloS One (www.plosone.org). In addition to Erickson, an associate professor in Florida State's Department of Biological Science and a research associate at the American Museum of Natural History, coauthors include Florida State University biologist Brian D. Inouye and other US scientists, as well as researchers from Germany and China. Responding to the Florida press release, John Noble Wilford wrote "Paper Challenges Idea About 'Early Bird Dinosaurs'" in the New York Times, Friday, October 9, 2009 (www.nytimes.com/2009/10/09/ science/09fossil.html?scp=l&sq=wilford early bird& st=cse). In the article Mr. Wilford describes the historical importance of Archaeopteryx, a specimen of which was first found in 1860, in southern Germany, about a year after the publication of Darwin's Origin of Species. The discovery at that time swayed many scientists toward accepting the theory of evolution by natural selection. The article also contains several brief statements from scientists involved in the research, as well as some who are not. In the scientific paper, the research team concluded that Archaeopteryx "was simply a feathered dinosaur that might have been capable of some aerial behavior, though perhaps not powered flight. In short, despite the feathers, it was not the archetypal bird." Paleontologists who were interviewed but not involved in the research said the findings were an important step in dinosaur-bird studies but not surprising. The bone growth, the basis for some of the conclusions in the research paper, was unbirdlike but reflected metabolic rates greater than those in nondinosaurian reptiles; that is they were more warm-blooded than cold-blooded.