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Related to Synapsids: Diapsids


Any of a group of amniote vertebrates that first emerged in the late Permian Period, characterized by a single opening in the temporal region on each side of the skull and including the mammals along with various extinct groups more closely related to mammals than to other amniotes.

[New Latin Synapsida, taxon name : syn- + Greek hapsis, hapsid-, arch (from the former belief that the single temporal opening on each side of the synapsid skull evolved by the fusion of the two temporal openings on each side of the diapsid skull ); see apsis.]

syn·ap′sid adj.


(sɪˈnæpsɪd) palaeontol
(Palaeontology) a fossil reptile (of the subclass Synapsida) that exhibits some mammal-like characteristics of the skull
(Palaeontology) relating to fossil reptiles of the subclass Synapsida
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.synapsid - extinct reptile having a single pair of lateral temporal openings in the skull
reptile, reptilian - any cold-blooded vertebrate of the class Reptilia including tortoises, turtles, snakes, lizards, alligators, crocodiles, and extinct forms
protomammal, therapsid - probably warm-blooded; considered direct ancestor of mammals
ictodosaur - intermediate in form between the therapsids and most primitive true mammals
pelycosaur - large primitive reptile having a tall spinal sail; of the Permian or late Paleozoic in Europe and North America
edaphosaurus - heavy-bodied reptile with a dorsal sail or crest; of the late Paleozoic
dimetrodon - carnivorous dinosaur of the Permian in North America having a crest or dorsal sail
References in periodicals archive ?
Non-mammalian synapsids (therapsids) are represented only by the large traversodontid cynodont Arctotraversodon plemmyridon (Hopson 1984; Sues et al.
This shows that caseid synapsids were much more ancient than previously documented in the fossil record.
In addition, the scoring of Mesosauridae, Millerettidae and Captorhinidae is corrected to '0' as the maxilla and quadratojugal are clearly separated by the jugal in these taxa (Gow, 1972; Modesto, 2006; Clark and Carroll, 1973) and to '0&1' for synapsids as these bones are connected in caseids, eothyrids and some varanopids but separated in other varanopids and ophiacodontids (Berman et al.
When a group of reptiles called the synapsids branched off from the main reptile line to become the precursors of mammals, the jaw again underwent changes.
Mammals are termed synapsids because they evolved from animals with one skull opening behind each eye.
Systematics of the nonmammalian Synapsida and implications for patterns of evolution in synapsids.
During the Middle Triassic, however, synapsids appear to be generally uncommon in tropical to subtropical Pangaean strata (as is the case for the Economy Member of the Wolfville Formation) while they are abundant at higher latitudes in both hemispheres (Sues and Fraser 2010).