A new skull of an early diverging rorqual (Balaenopteridae, Mysticeti, Cetacea) from the late Miocene to early Pliocene of Yamagata, northeastern Japan

• Published in: Palaeontologia Electronica
• Main Authors: Tanaka, Yoshihiro, Nagasawa, Kazuo, Taketani, Yojiro
• Format: Article in Journal/Newspaper
• Language: English
• Published: Coquina Press
• Subjects: rorquals; Balaenopteridae; Noguchi Formation; Furukuchi Formation; Miobalaenoptera numataensis; ontogenetic variation; 457; Balaenoptera musculus; Blue whale
• Online Access: http://hdl.handle.net/2115/90473; https://doi.org/10.26879/1002

The family of rorquals and humpback whales, Balaenopteridae includes the larg-est living animal on Earth, the blue whale Balaenoptera musculus. Many new taxa have been named, but not many from the western Pacific, except Miobalaenoptera numataensis from Japan. Here we describe an early balaenopterid, cf. M. numataensis from a late Miocene to early Pliocene sediment in Yamagata Prefecture, northeastern Japan. The species has a straight and sharp lateral ridge of the fovea epitubaria at the ventral surface of the periotic, and a dorsoventrally thin pars cochlearis. The new spec-imen provides knowledge of supposed ontogenetic variation and periotic morphology in poorly known fossil balaenopterids.