Magazine article Science News

Better Traces of Whale Pedigree Discovered

Magazine article Science News

Better Traces of Whale Pedigree Discovered

Article excerpt

Many paleontologists believe that Pakicetus, a carnivorous mammal that flourished 50 million years ago, helped bridge the evolutionary gap between whales and their land-dwelling ancestors.

Now, fossils uncovered in Pakistan provide the best evidence to date that Pakicetus teetered on the midpoint of this radical evolutionary change, pursuing its meals in the water but spending significant time on dry land.

Arguments for this theory hinge on whether Pakicetus had the hearing of a land-dwelling or a marine mammal. Newly recovered jaw and middle-ear bones strongly indicate that Pakicetus was not well adapted for underwater hearing, says paleontologist Hans Thewissen of Duke University School of Medicine in Durham, N.C. Thewissen discussed the new Pakicetus fossils and their implications at last week's meeting of the Society of Vertebrate Paleontology in Toronto, Canada.

"I think for the first time there is what you could call a missing link -- if there is such a thing as a missing link -- between the hearing mechanism of the marine mammal and the terrestrial mammal," he says.

Thewissen and paleontologist S. Taseer Hussain of Howard University College of Medicine in Washington, D.C., unearthed the fossils in the Kala Chitta Hills of the Punjab region of Pakistan. Researchers found the first remains of such creatures at the same site more than a decade ago. The deposits, called the Kuldana Formation, have also yielded fossilized ancestors of sea cows.

According to a widely accepted theory, whales have large fat pads in their jaws that channel sound vibrations to each ear. …

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