 They were first described in 1978 by Daryl Domning when fossils in California were unearthed.Its appearance and behavior are largely based on that of the well-documented Steller's sea cow, who, unlike the Cuesta sea cow, lived into modern times and was well described.The fossils of the Cuesta sea cow were first discovered in the Late Pliocene sediment formations of Pismo Beach, California in 1978, and following finds of the species were unearthed in California.