MU study finds that even fossilized plant-eating crocodiles replaced their teeth
COLUMBIA, Mo. – Unlike people, crocodiles do not clean their teeth to slow down wear and tear. Instead, they get rid of them and replace them with new copies. (more…)
Researchers have discovered well-preserved pelves and a partial pelvic fin from Tiktaalik roseae, a 375 million-year-old transitional species between fish and the first legged animals, which reveal that the evolution of hind legs actually began as enhanced hind fins. This challenges existing theory that large, mobile hind appendages were developed only after vertebrates transitioned to land.
The scientists describe the fossils in the Proceedings of the National Academy of Sciences, online on Jan. 13. The piece marks the inaugural article for Prof. Neil Shubin, Robert R. Bensley Distinguished Service Professor of Organismal Biology and Anatomy, as a member of the National Academy of Sciences. (more…)
Answer may be ‘adaptive zones’ that limit species number, life scientists report
There are more than 400,000 species of beetles and only two species of the tuatara, a reptile cousin of snakes and lizards that lives in New Zealand. Crocodiles and alligators, while nearly 250 million years old, have diversified into only 23 species. Why evolution has produced “winners” — including mammals and many species of birds and fish — and “losers” is a major question in evolutionary biology.
Scientists have often posited that because some animal and plant lineages are much older than others, they have had more time to produce new species (the dearth of crocodiles notwithstanding). This idea — that time is an important predictor of species number — underlies many theoretical models used by biologists. However, it fails to explain species numbers across all multi-cellular life on the planet, a team of life scientists reports Aug. 28 in the online journal PLoS Biology, a publication of the Public Library of Science. (more…)
UD’s Schmidt studies genome of crocodile family in evolution research
University of Delaware scientist Carl Schmidt is working to identify genes in crocodiles, alligators and gharials as he searches for links between the creatures that could give clues as to how they evolved over the years in relation to one another.
Schmidt’s effort is part of a National Science Foundation-funded project being conducted by a team of researchers assembled by David Ray, an evolutionary biologist at Mississippi State University. (more…)
