Also found in: Thesaurus.
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|Noun||1.||subclass Synapsida - extinct reptiles of the Permian to Jurassic considered ancestral to mammals|
class Reptilia, Reptilia - class of cold-blooded air-breathing vertebrates with completely ossified skeleton and a body usually covered with scales or horny plates; once the dominant land animals
order Therapsida, Therapsida - extinct mammal-like reptiles found inhabiting all continents from the mid Permian to late Triassic
class - (biology) a taxonomic group containing one or more orders