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Temporal range: Pliocene
Semirostrum ceruttii skull.jpg
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Family: Phocoenidae
Genus: Semirostrum
Racicot et al., 2014
S. ceruttii
Binomial name
Semirostrum ceruttii
Racicot et al., 2014

Semirostrum ceruttii is an extinct porpoise that lived between 5 and 1.5 million years ago (Ma), during the Pliocene epoch. The species is highly distinctive due to the extremely long symphysis on the lower jaw, reaching lengths of 85 centimeters (33.46 inches), while that of a modern porpoise are 1–2 centimeters (0.39–0.79 inches) long. The main hypothesis regarding its use is 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.[1]

S. ceruttii restoration


  1. ^ 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. 24 (7): 774–779. doi:10.1016/j.cub.2014.02.031. PMID 24631245.CS1 maint: Multiple names: authors list (link)