科研之友
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摘要
We present new and well-preserved giant salamander material from the Miocene of the Grytsiv locality, Ukraine. Disarticulated skull and postcranial bones from two individuals are described as a new taxon, Ukrainurus hypsognathus, gen. et sp. nov. U. hypsognathus is characterized by poorly ossified bone tissues, relatively inflexible mandibles, a high dentary, a crista on the lingual surface of the dentary, a pars dentalis of the dentary that is composed of a dental lamina and a subdental surface, presence of an eminentia dorsalis on the squamosal, a broad pericondylar facet on the occipital, extremely elongated prezygapophyses, and hemal processes with an elongate, oval base. Moreover, U. hypsognathus shows evidence of strong mandibular levator muscles that indicate great biting force. A phylogenetic analysis of all well-understood Tertiary and Recent giant salamanders recovers a monophyletic group of Asian and North American cryptobranchids, but places U. hypsognathus outside crown group Cryptobranchidae. This result suggests that Cryptobranchidae originated in Asia and dispersed to North America. The oldest representative of crown Cryptobranchidae is Aviturus exsecratus from the terminal Paleocene of the Nemegt Basin, Mongolia.
- 出版日期2013
