The Nature Conservancy in California - Prehistoric Fossil Found on Santa Cruz Island

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Fossilized whale jawbone excavation on Santa Cruz Island
Fossilized jawbone, most likely from a baleen whale, discovered in January 2009 on Santa Cruz Island. This and other bones were excavated for study by paleontologists.

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What was originally thought to be a mammoth tusk turns out to be a significantly older find — a jawbone from a whale.

“This is really exciting, especially given the fossil’s age and preserved condition. This bone could be 10–20 million years older than we first thought. It is a jawbone that is most likely from an extinct species of baleen whale,” said the Conservancy’s Dr. Lotus Vermeer, project director of Santa Cruz Island. Baleen whales have no teeth but rather filter their food through plates of baleen, which is made of keratin, the same substance that composes hair and nails. These whales are generally larger than their toothed cousins.

Discovered on the island in mid-January, the fossil, and other bones found nearby, were originally thought to be from a pygmy mammoth, which would have roamed the island approximately 47,000 years ago. But a team of scientists delicately excavated the jawbone from sediments they speculated had been formed 10 to 25 million years ago. The other bones include what may be a portion of a marine mammal skull, and they were buried deeper.

The jawbone was helicoptered to the mainland, where marine mammal paleontologists will study it to determine its species and age.

“I do not know of other whale fossils this nice from Santa Cruz Island, or from any of the other Channel Islands,” commented Dr. Lawrence G. Barnes, curator of vertebrate paleontology at the Natural History Museum of Los Angeles County, on seeing photographs of the excavated bone.

“This find is valuable and significant,” Dr. Barnes continued. “Because the evolutionary (fossil) history of this group of whales is only understood in a very general way, a fossil like this can potentially fill a gap in our knowledge of the group.”

“It’s fascinating to come across bones this old. We can learn so much from a find like this,” concluded Vermeer.

Nature picture credits (top to bottom, left to right): Photo © Gary Crabbe/Enlightened Images (Santa Cruz Island); Photo © Lotus Vermeer/TNC (excavation of fossilized jawbone); Photo © Lotus Vermeer/TNC (fossilized jawbone discovered on Santa Cruz Island).