Early Miocene cetacean diversity in the Vaqueros Formation, Laguna Canyon, Orange County, California

Recent discoveries in the San Joaquin Hills of Orange County, California, have revealed a diverse and significant collection of marine mammals from the Early Miocene Vaqueros Formation. The cetaceans from Laguna Canyon constitute a unique fauna of unprecedented diversity, and warrant the establishment of a new fauna. Here I name the Laguna Canyon Local Fauna to encompass the cetaceans and other marine mammals from the Vaqueros Formation in the San Joaquin Hills. Approximately equal numbers of taxa of the two major clades of cetaceans, Mysticeti and Odontoceti, are represented, although toothed whales (Cetacea: Odontoceti) dominate the fauna in number of individuals. Baleen whales (Cetacea: Mysticeti) are also present, and primitive toothed forms and more modern baleen-bearing taxa are both represented in this collection. Prior to the discovery of this assemblage, toothed mysticetes were not known to survive later than the end of the Oligocene. At Laguna Canyon, there are individuals from three different taxa of toothed mysticetes, indicating that they were much more widespread temporally and geographically than previously known. As a whole, the Laguna Canyon Local Fauna is typified by primitive odontocetes, diverse toothed mysticetes, primitive baleen-bearing mysticetes, sirenians, and desmostylians. The Laguna Canyon Local Fauna represents a previously unknown diversity of Early Miocene cetaceans from the North Pacific realm.