Allodesmus is an extinct genus of pinniped from the middle to late Miocene of California and Japan that belongs to the extinct pinniped family Desmatophocidae. Allodesmus measured about 8 feet (2.4 m) long and weighed 800 pounds (360 kg). Allodesmus had the specific anatomical features found in modern polygynous pinnipeds: sexual dimorphism, strong canines for fights between bulls and teeth with well-defined growth zones, a result from periodic fasting (in order to defend their harem, males would not take to the sea to feed during the breeding season).
Sharktooth Hill is one of the most famous vertebrate fossil sites in the world - a place where roughly 125 species of sharks, bony fishes, sea mammals, sea turtles, marine crocodiles, birds and even land mammals have been found.
The fossils are concentrated in a rather narrow one-to four-foot thick layer in the Round Mountain Silt Member of the Middle Miocene Temblor Formation, which is exposed over several square miles in the rolling foothills of California's southern Sierra Nevada.
Since it’s discovery in 1853, the Sharktooth Hill area has yielded thousands of shark teeth, including the rare giant shark, Otodus megalodon!