Karen Sears, at the University of Colorado Health Sciences Center in Denver, has discovered why intermediate forms may be missing in the fossil record.A change to a single gene allowed bats to grow wings and take to the air, a development that may explain why bats appeared so suddenly in the fossil record some 50 million years ago.
Bats have been an evolutionary enigma. That’s because the oldest fossil bats look remarkably like modern ones, each having wings formed from membranes stretched between long fingers, and ear structures designed for echolocation. No fossils of an animal intermediate between bats and their non-flying mammal ancestors have been found. We’ve never had an adequate explanation” for the sudden appearance of bats, Nancy Simmons of the American Museum of Natural History in New York told New Scientist. “This sounds like a remarkable discovery.”
The lack of transitional forms has also led to speculation about the origin of bats, with some believing that primates are their closest relatives. Genetic studies now show they are closest to ferungulates, which include horses and pigs, or to the shrews and moles.
Storyteller : Karen Sears, at the University of Colorado Health Sciences Center in Denver
http://www.newscientist.com/article.ns?id=dn6647
Story Reteller : Dave Thomas of Panda's thumb http://www.pandasthumb.org/archives/2004/11/a_quantum_leap.html
Storyteller 2 : Jennifer S. Holland, National geograghic
Sixty million years ago, on a planet crawling with mammals, one tree dweller rose above the crowd on paper-thin wings
.jpg)
Posts
No comments:
Post a Comment