Mammals Beat Reptiles in Battle of Evolution »

Mammals, birds and fish are among evolution’s "winners," while crocodiles and other reptiles have ended up on the losing end, a new study suggests.

"Our results indicate that mammals are special," said study leader Michael Alfaro of UCLA.

The research allowed scientists to calculate for the first time which animal lineages have exceptional rates of success. The so-called "winners" have more species in their group, which means they have successfully evolved and diversified into many types of environments. The losers have diversified less, even over the course of millions of years.

The distinction doesn't imply that the losers are under a greater threat of extinction, however. Even rich, diverse lineages include endangered species.

The evidence

To separate the winners from the losers, a group of scientists analyzed DNA sequences and fossils from 47 major vertebrate groups, and used a computational approach to calculate whether the species richness (a way of measuring biodiversity) of each of these 47 groups is exceptionally high or low.

The winners: most modern birds, including the songbirds, parrots, doves, eagles, hummingbirds and pigeons; most mammals; and a group of fish including most of the fish that live on coral reefs.

The losers: crocodiles and alligators and a reptile cousin of snakes and lizards known as the tuatara.

The winners showed remarkable species richness, especially for the relatively short time some groups have been on the planet.

The research was funded by the National Science Foundation.

Read Full Story at livescience.com »

158 Views Share Story 0 Comments Report