LAUSR

Abstract Balaenopteroidae is a diverse superfamily within the mysticetes that consists of numerous recent fossil species. The publication of new taxa has increased, which improves the knowledge about this group. In this work, we name and describe Kennedycetus pericorum from the Late Miocene deposits of the Trinidad Formation in Baja California Sur, Mexico. Our phylogenetic results indicate that this is a step taxon, far from the balaenopterid crown group, that is closely related to Norrisanima miocaena from the Monterey Formation, California. The associated fauna of K. pericorum includes the internal molds of different mollusks attributable to Glycymeridae, Semelidae, and Lucinidae, which indicate a coastal environment of warm waters.