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Transitional Fossils

April 17, 2008

A listener asks: Have many transitional fossils showing evolutionary links between major groups of animals been found in the fossil record?


Filling in the fossil record…I’m Bob Hirshon and this is Science Update.

Listener Derek Wilmott of Clemson, South Carolina emailed to ask if many transitional fossils linking major groups of animals have been found in the fossil record. According to vertebrate paleontologist Donald Prothero of Occidental College, early fossils are scarce in some animals like the amphibians.

DONALD PROTHERO (Occidental College):
But in general we have huge numbers of transitional fossils.

Examples include fossil whales, which show adaptations both for walking on land and living part of the time in water. And the famous Archaeopteryx has both dinosaur-like characteristics like a bony tail and teeth and bird-like features like feathers. He says that fossilization is a very rare process.

Maybe 1/10th of 1% of all species that have lived on the planet are still preserved as fossils. So you don’t expect to find that many, and it’s really remarkable that we have as many as we do.

I’m Bob Hirshon for AAAS, the science society.