Easter Surprise: World's Oldest Rabbit Bones Found

Brian Handwerk
for National Geographic News

March 21, 2008

You need some serious luck to find a 53-million-year-old rabbit's foot.

As it happens, Kenneth Rose was so fortunate—but it took him a few years to realize it.

The Johns Hopkins University School of Medicine anatomy professor unearthed curious bones in India several years ago.

He suspected they were important but could not identify them. So he stored them in a drawer until serendipity struck in spring 2007.

"One day I was teaching my mammals course and showing the [students] the foot of a jackrabbit, and I said, 'Hey, that's what we have in the drawer.'"

That fateful foot now appears to belong to the world's earliest known rabbit found so far, some three to four million years older than its closest contemporary.

Though modern jackrabbit feet are about four times larger, they match the 0.25-inch-long (6.4-millimeter-long) Indian fossils in shape.

"All we have is ankle bones. We'd sure like to find some teeth or skulls, but this is what we have at the moment—and they are unmistakable," Rose said.

Rose received funding from the National Geographic Society. (The National Geographic Society owns National Geographic News.)

(Related news: "Mystery Mammal Fossil Found in India" [November 8, 2007].)

More Rabbit-Like

Previous studies have suggested that rabbits and hares diverged from pikas—mouse-like mammals that are also part of the order Lagomorpha—some 35 million years ago.

But Rose and colleagues believe the new bones show that advanced rabbit-like features evolved as far back as the early Eocene, which lasted from 54.8 to 33.7 million years ago.

"They don't look like pikas, they look more like rabbits," he said.

Robert Asher, a zoologist at Cambridge University in the United Kingdom who is unaffiliated with the research, agreed.

"The particular importance of this is that it documents the oldest occurrence of a crown lagomorph—that is, a lagomorph that shares a closer relationship to rabbits and hares to the exclusion of pikas," he said.

Out-of-Asia Theory

The rabbit's occurrence in India initially threw Rose for a loop.

No rabbits older than about 18 million years old have ever been discovered on the Indian subcontinent.

The previous oldest known rabbits had all been unearthed in Central Asia, where it is commonly believed the animals originated.

But that doesn't mean rabbits have an Indian origin, Rose said.

"The likelihood from the other evidence we have is the [origin of rabbits] was probably in Central Asia," he explained.

For instance, Gomphos elkema was present in this region, and must have been in the group that gave rise to lagomorphs, Rose said.

The 55-million-year-old G. elkema is a primitive rabbit ancestor that has features of both rodents and lagomorphs, which likely share a common lineage.

Rose's research was published online in the February issue of the Proceedings of the Royal Society B.

Globe Hoppers

Cambridge's Asher said these early rabbits were likely on the move.

"We know that the Indian subcontinent had land connections with the Asian mainland since at least the base of the Eocene," he said.

"So it's not surprising that we have some kind of lagomorph on the subcontinent by this time in Earth's history."

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