Scientists Discover Fossils of Extinct Porpoise Species With Very Unusual Jaw
Posted on March 13, 2014
Scientists have discovered fossils of an extinct species of ancient porpoise. The extinct Californian porpoise, Semirostrum ceruttii, had a chin length unprecedented among known mammals. The porpoise had an extension of its jaw, called a symphysis, that measured 85 centimeters (33.5 inches) in the best-preserved specimen. By comparison, the typical of a crown porpoise measures just one or two centimeters.
Rachel Racicot, the Yale doctoral candidate who is the lead author of the research, said in the announcement, "This is unique anatomy for a mammal. And it tells us that porpoises once searched for food in a very different way than they do now."
The scientists published a research paper on the porpoise in Current Biology. In the paper, the researchers explain how they believe Semirostrum dug for food lodged in the seabed (a benthic feeder). One of the specimens is very well preserved. CT scans of this specimen revealed nerve canals leading from the creature's symphysis into the rear of its skull. The scientists say this indicates the protuberance "was highly sensitive and could relay meaningful information to the animal's brain."
The species lived 1.5 to 5.3 million years ago along the California coast. It was named after its unusual jaw and a paleontologist. "Rostrum" means the lower half of the jaw. The "cerutti" portion of the name comes from Richard A. Cerutti, a paleontologist at the San Diego Natural History Museum who discovered the best-preserved specimen.
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