plural noun Syn·ap·si·da \-psədə\

Definition of Synapsida

  1. :  a subclass of Reptilia comprising extinct reptiles of the Pennsylvanian, Permian, and Triassic, having a single pair of lateral temporal openings in the skull, and usually held to be ancestral to the true mammals — compare ictidosauria, therapsida

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Origin and Etymology of synapsida

New Latin, from synapsis + -ida

Seen and Heard

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a brief usually trivial fact

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