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Joumocetus
''Joumocetus'' is a genus of extinct baleen whale in the family Cetotheriidae containing the single species ''Joumocetus shimizui''. The species is known only from a partial skeleton found in Miocene age sediments of Japan. History and classification ''Joumocetus shimizui'' was described from a mostly complete cranium and associated portions of both mandibles, cervical and thoracic vertebrae. The skeleton was recovered from an outcrop of the earliest late Miocene, Serravallian age Haraichi Formation exposed along the Kabura River near Yoshii, Gunma Prefecture, Japan (, paleocoordinates ).. Retrieved October 2013. The Haraichi Formation includes several tuff layers which have been used for dating. The type skeleton was found between the older Baba tuff and the younger Kamikoizawa tuff. Biotite specimens taken from the Baba tuff have yielded an 40argon–39argon date of , while sanidine specimens gave a 40argon–39argon date of . The overlying Kamikoizawa tuff has not been dat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cetotheriidae
Cetotheriidae is a family of baleen whales (parvorder Mysticeti). The family is known to have existed from the Late Oligocene to the Early Pleistocene before going extinct. Although some phylogenetic studies conducted by recovered the living pygmy right whale as a member of Cetotheriidae, making the pygmy right whale the only living cetotheriid, other authors either dispute this placement or recover Neobalaenidae as a sister group to Cetotheriidae. Taxonomy After its description by Brant in 1872, Cetotheriidae was used as a wastebasket taxon for baleen whales which were not assignable to extant whale families. Comparing the cranial and mandibular morphology of 23 taxa (including late archaeocetes and both fossil and extant mysticetes), found Cetotheriidae in this traditional sense to be polyphyletic. Based on ten cranial characters, they also concluded that of the twelve included fossil baleen-bearing mysticetes, six formed a monophyletic group, Cetotheriidae ''sensu stricto' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |