Trachelosauridae

Extinct clade of reptiles

Trachelosauridae is an extinct clade of archosauromorph reptiles that lived throughout the Triassic period. Like their close relatives the tanystropheids, they were "protorosaur"-grade archosauromorphs characterized by their long necks. Unlike tanystropheids, which lengthen their neck primarily by elongating the individual cervical (neck) vertebrae, trachelosaurids achieved their long necks by the addition of more vertebrae. The most extreme example of this trend was Dinocephalosaurus, which had at least 32 vertebrae in the neck alone, far more than the 13 neck vertebrae of Tanystropheus.

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