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.
"It is not surprising that it was born on land," said Gingerich, who has received funding for his work from the National Geographic Society's Committee for Research and Exploration. (National Geographic News is owned by the National Geographic Society.)
"There is a high rate of mortality associated with giving birth at sea," he said. Newborn whales risk drowning, getting lost, and being eaten by sharks, among other things.
"On land, you still have to hide, but there are fewer threats," he explained.
The fossil is a cousin of the contemporary early whales Rodhocetus and Artiocetus, which came from the same fossil beds.
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