Abstract

HERNANDEZ CISNEROS, Atzcalli Ehécatl; GONZALEZ BARBA, Gerardo  and  FORDYCE, Robert Ewan. Oligocene cetaceans from Baja California Sur, Mexico. Bol. Soc. Geol. Mex [online]. 2017, vol.69, n.1, pp.149-173. ISSN 1405-3322.

Baja California Sur has an important Cenozoic marine fossil record which includes diverse but poorly known Oligocene cetaceans from Mexico. Here we review the cetacean fossil record including new observations from materials that elucidate the evolution of the Neoceti in the Pacific basin. Fossils were collected from outcrops of the El Cien Formation (Oligocene-Early Miocene) and from San Gregorio Formation (Late Oligocene). The specimens belong to the paleontological collection of Museo de Historia Natural de la Universidad Autónoma de Baja California Sur. An estimated 26 unnamed species include toothed cetaceans: possible “archaeocetes” (?Kekenodontidae); archaic Odontoceti; and the basal group Aetiocetidae, toothed mysticetes (Mysticeti). Toothless mysticetes (Chaeomysticeti) include the basal group Eomysticetidae, and balaenopterids-like forms. The Oligocene cetaceans from Baja California Sur, Mexico are diverse and represent the most southern such assemblages known from North America.

Keywords : Mysticeti; Odontoceti; Mexico; fossils; Late Oligocene.