Saturday, 6 August 2011
Turning a Bird Into a Dinosaur
Archaeopteryx looks like a bird but some researchers think it might not be.
When a fossil bird has wings and feathers, looks like a bird, and has a bird’s beak and a wishbone, one might think that it is a bird.
For decades, Archaeopteryx has nevertheless been a source of controversy because it also has some traits that reptiles usually have, such as a long bony tail, teeth and claws on its wings (well, few reptiles actually have wings but claws are so reptilian) and it suits neo-Darwinian thinking as a link between birds and reptiles.
Writing in the March 2003 issue of Scientific American, Richard Prum and Alan Brush acknowledged: “Archaeopteryx offers no new insights on how feathers evolved, because its own feathers are nearly indistinguishable from those of today's birds."
However, the journal Nature recently published a paper on the discovery of Xiaotingia zhengi, which threatens to topple Archaeopteryx from its perch.
The fossil was purchased from a dealer, so one cannot be absolutely certain of where it hails from. Xing Xu, a palaeontologist at the Institute of Vertebrate Palaeontology and Palaeoanthropology in Beijing, the main author of the paper, nonetheless believes that Xiaotingia hails from western Liaoning in China and that it was found in Late Jurassic rocks dated at 161–145 million years ago.
Xing Xu and colleagues believe that Xiaotingia zhengi is a dinosaur. While there is no explicit evidence that it had feathers, its measurements resemble that of Archaeopteryx. And since it might be a bit older than the 150 million-year old “Archie”, they believe that while still a dinosaur, it is the great uncle of all birds.
The feathers and other avian features of Archaeopteryx do not weigh much in the quest to provide proof for the dino to bird connection. Neither does other contrary evidence.
Kaplan, Matt. 2011. Archaeopteryx no longer first bird. Nature news (27 July).
Prum, Richard O. and Alan H. Brush. 2003. Which Came First, the Feather or the Bird? Scientific American 288 (3): 60 –69.