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Any of a group of chiefly extinct reptiles that first emerged in the early Permian Period and are characterized by a skull with no openings in the temporal region. Modern turtles and tortoises may be surviving members of this group, or they may be descendants of diapsids that lost their skull openings.

[New Latin Anapsida, former subclass name : an- + Greek hapsis, hapsid-, arch (in reference to their lack of temporal openings); see apsis.]
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.anapsid - primitive reptile having no opening in the temporal region of the skullanapsid - primitive reptile having no opening in the temporal region of the skull; all extinct except turtles
reptile, reptilian - any cold-blooded vertebrate of the class Reptilia including tortoises, turtles, snakes, lizards, alligators, crocodiles, and extinct forms
Anapsida, subclass Anapsida - oldest known reptiles; turtles and extinct Permian forms
chelonian, chelonian reptile - a reptile of the order Chelonia
diapsid, diapsid reptile - reptile having a pair of openings in the skull behind each eye
References in periodicals archive ?
One major difference between anapsid and diapsid reptiles is in the cheek or temporal area of the skull.
Generations of paleontologists have regarded turtles as outsiders among modern reptiles--holdovers from an ancient group called anapsids that lack holes in the sides of their skulls.
Turtles lack any such holes and so are the only living anapsids, a group that includes fossils of the most primitive vertebrates capable of living entirely on land.