National Geographic: Rare fossil of pregnant whale is missing-link

Vertebrate paleontologist Louis L. Jacobs, a professor in Dedman College‘s Roy M. Huffington Department of Earth Sciences, is quoted in the February 3 online story “Early whales gave birth on land, fossils reveal” by National Geographic News Service.

Jacobs is known for his work documenting changes in fossil mammals in Pakistan, which helps scholars correlate climatic changes with evolutionary changes seen in animals, and which helps calibrate the rate of DNA evolution in mammals. He’s also credited for discovery of what’s now known as “Malawisaurus,” a plant-eating dinosaur that lived in Malawi, Africa, 115 million years ago.

Excerpt

By Tasha Eichenseher
National Geographic News

It’s an evolutionary discovery Darwin himself would have been proud of.

Forty-seven million years ago primitive whales gave birth on land, according to a study published this week that analyzes the fossil of a pregnant whale found in the Pakistani desert.

It is the first fetal fossil from the group of ancient amphibious whales called “Archaeoceti,” as well as the first from an extinct species called “Maiacetus inuus.”

When the fossil was discovered, nine years ago, University of Michigan paleontologist Philip Gingerich was thrown off by the jumble of adult and fetal-size bones.

“The first thing we found [were] small teeth, then ribs going the wrong way,” Gingerich said. Later, “it was just astonishing to realize why the specimen in the field was so confusing.”

The head-first position of the fetus was especially telling.

Land mammals are generally born head first, and marine mammals are born tail first. …

Whales’ slow transition from land to sea is documented in other fossils, but this is the most complete to fill a gap during this time period…..

“This is a big discovery because it tells us about life history, or the way early whales lived their lives, [which is something] that is difficult to learn from fossils,” Gingerich said.

The most famous other seafaring animals to be found fossilized with a complete fetus were ichthyosaurs, a reptile group that lived roughly 245 to 100 million years ago.

“Not since have we seen fossils of marine-dwelling vertebrates that tell us so much about the biology of evolving an ocean dwelling way of life from a terrestrial ancestor,” said Louis Jacobs, a vertebrate paleontologist at Southern Methodist University in Texas.

“It is a missing link of the most informative sort,” Jacobs added.

“Charles Darwin would delight.”

Read the full story

Related links:
Natl Geo News: Early whales gave birth on land, fossils say
LiveScience story: Ancient whales gave birth on land
LiveScience.com: Surprising whale discoveryvideo.jpg
Louis L. Jacobs
Roy M. Huffington Department of Earth Sciences
Dedman College of Humanities and Sciences

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