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Shastasauridae
Shastasauridae is an extinct family of Triassic ichthyosaurs that includes the genera '' Shastasaurus'', ''Shonisaurus'' and ''Himalayasaurus''. Many other Triassic ichthyosaurs have been assigned to Shastasauridae in the past, but recent phylogenetic analyses suggest that these species form an evolutionary grade of early ichthyosaurs rather than a true clade or evolutionary grouping that can be called Shastasauridae. Shastasauridae was named by American paleontologist John Campbell Merriam in 1895 along with the newly described genus ''Shastasaurus''. In 1999, Ryosuke Motani erected the clade Shastasauria to include ''Shastasaurus'', ''Shonisaurus'', and several other traditional shastasaurids, defining it as a stem-based taxon including "all merriamosaurians more closely related to '' Shastasaurus pacificus'' than to ''Ichthyosaurus communis''." He also redefined Shastasauridae as a node-based taxon including "the last common ancestor of ''Shastasaurus pacificus'' and '' Besan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Himalayasaurus
''Himalayasaurus'' is an extinct genus of ichthyosaur from the Late Triassic Qulonggongba Formation of Tibet. The type species ''Himalayasaurus tibetensis'' was described in 1972 on the basis of fragmentary remains, including teeth, limb bones, and vertebrae.Z.-M. Dong. (1972). An ichthyosaur fossil from the Qomolangma Feng (Mt. Everest) region. ''Gu ji zhui dong wu yu gu ren lei yan jiu suo ji kan'' 9:7-10 The entire body length of ''Himalayasaurus'' is estimated to have been over in length. ''Himalayasaurus'' has since been considered a ''nomen dubium'' or "dubious name" because of the lack of features that set it apart from other ichthyosaurs, although the presence of distinct cutting edges on its teeth have more recently been proposed as a unique feature of the genus (cutting edges have also been found in the recently described ichthyosaur ''Thalattoarchon'' from the western United States). ''Himalayasaurus'' belongs to the family Shastasauridae, which includes other large-bod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |