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Nov 26, 2008 | 10
Ever wonder how a turtle got its shell? You're not the only one. Evolutionary biologists and paleontologists have long been stumped by the question. But a recently unearthed turtle fossil, the oldest on record, may hold the answer. Researchers report in Nature today that the fossil indicates shells evolved as an extension of turtles' backbones and ribs.
"Its discovery opens a new chapter in the study of the origins and early history of these fascinating reptiles," says vertebrate paleontologists Robert Reisz and Jason Head of the University of Toronto, in a commentary accompanying the article.
Scientist have been in the dark until now because all fossilized turtles previously discovered had complete shells. But this 220 million-year-old fossil is an ancestor of the modern turtle at a stage when its shell was still evolving.
Oct 10, 2008
An Atlantic blacktip shark spontaneously reproduced without the company of a mate, scientists report in the second documented case of the phenomenon.
Five-foot-long (1.5-meter) Tidbit, the ironically named resident of the Virginia Aquarium & Marine Science Center in Virginia Beach, Va., spawned on her own — no male assistance involved, according to Reuters. Sadly, Tidbit died in May 2007 during a veterinary checkup, before birthing her until-then unknown 10-inch-long shark pup. The case is published in the new issue of the Journal of Fish Biology.
Scientists last year wrote about an asexual hammerhead shark that reproduced on its own, a process called parthenogenesis in which unfertilized eggs divide. Bony fish, reptiles, birds, lizards and Komodo dragons also can reproduce asexually.
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