Pelagiarctos is a genus of walrus that lived in the Miocene Epoch of California.
Fossils of Pelagiarctos are rare and grossly incomplete, but skull material indicates that it measured approximately 2.5 to 3 meters long and weighed about 350 kilograms. Its cheek teeth resemble those of several modern terrestrial carnivores, which indicates that it probably had a large bite force.
Originally, Pelagiarctos was described as a seal, but it is now believed to be a type of walrus.
At first, Pelagiarctos was imagined as a "killer walrus", a carnivore feeding on large aquatic animals and even other pinnipeds. However, recent analysis indicates that it actually fed on smaller animals like fish, with only the occasional larger meal.
Only a handful of fossils of Pelagiarctos have ever been found, and only in one place. It is possible that the walrus may have migrated, explaining its rarity.
- Barnes, Lawrence G. (1988-03-18). "A New Fossil Pinniped (Mammalia: Otariidae) from the Middle Miocene Sharktooth Hill Bonebed, California" (PDF). Contributions in Science (Kansas: Natural History Museum of Los Angeles County) (396): 1–11.
- Boessenecker, R.W. and M. Churchill. 2013. A reevaluation of the morphology, paleoecology, and phylogenetic relationships of the enigmatic walrus Pelagiarctos. PLoS One 8(1) e54311. doi:10.1371/journal.pone.0054311.
- Boessenecker, Robert (January 21, 2013). Was Pelagiarctos a "killer" walrus? Part 3: new specimen from Orange County. The Coastal Paleontologist (Down Under). Retrieved January 23, 2013.
- Switek, Brian (January 18, 2013). Dissecting the "Killer" Walrus. Laelaps. Retrieved January 23, 2013.