Semirostrum
Semirostrum is a genus of extinct cetacean belonging to the family Phocoenidae, and lived between 5 and 1.5 million years ago (Ma), during the Pliocene epoch. The species is highly distinguished due to the extremely long symphysis on the lower jaw, reaching lengths of 85 centimeters (33.46 inches), while that of a modern porpoise (it's closest living descendant) are 1 - 2 centimeters (0.39 - 0.79 inches) long. The main theory of its use is believed to be that it probed along the sediment in the murky estuaries and shores of what is now California, in search of food, which would easily be scooped up the symphysis and into the jaws. The etymology of the name means "Half Beak", referring to the upper jaw being half the length of the lower. The species name is S. ceruttii.[1]
References
- ^ Rachel A. Racicot, Thomas A. Deméré, Brian L. Beatty & Robert W. Boessenecker (2014). "Unique Feeding Morphology in a New Prognathous Extinct Porpoise from the Pliocene of California". Current Biology. doi:10.1016/j.cub.2014.02.031.
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