Science / Medicine : Fossil Believed to Be New Species

Paleontologists have recovered bones that they say represent a stunning, newly identified species of extinct porpoise that had a dramatically protruding lower jaw. The function of the protrusion, which extends about eight inches beyond the point where the mouth closes over the teeth, is unclear. It has not been seen in any known porpoise, dolphin or whale species living or extinct, said San Diego Museum of Natural History paleontologist Tom Demere.

The 3-million-year-old fossil skull, lower jaw and inner ear bones of the porpoise were recovered from a Chula Vista construction site. Richard Cerutti, a museum research assistant assigned to the site, found the fossil while walking behind a bulldozer that was leveling a hill last summer.

It was recovered from sandstone that formed 3 million years ago when much of the San Diego area from Mission Bay to the Mexican border was a shallow alcove shaped much like Monterey Bay is now.

Demere speculated that the toothless snout extension--a bone structure that would have been covered with skin--may have been used to swat and stun fish or other prey. But it may have been some sort of sexual display or had no function at all, Demere added.