The dugong (sea cow) is found here. Commercial hunting lead to the extinction of Steller's sea cow and the Caribbean monk seal. This led to the extinction of the Steller's Sea Cow and the Caribbean monk seal. The largest-known desmostylian was a species comparable in size to the Steller's Sea Cow. This has led some to believe that the Takikawa sea cow is its own species. Crews gave it the more appropriate name "Sea Cow". By 1768, Steller's sea cow was extinct. For decades after its discovery, no skeletal remains of a Steller's sea cow were discovered. Sea cow sightings have been reported after Brandt's official 1768 date of extinction. The Steller's sea cow became extinct in the 18th century. Whether Steller's sea cow had any natural predators is unknown. This suggests that the sea cow had a far more extensive range in prehistoric times. Steller described the sea cow as being highly social (gregarious). Steller's sea cow went extinct due to overhunting in 1768. The sea cow had no gallbladder, but did have a wide common bile duct.