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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.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
References in periodicals archive ?
ANAPSID.ORG, (last updated
"With Eorhynchochelys's diapsid skull, we know that turtles are not related to the early anapsid reptiles (those without openings), but are instead related to evolutionarily more advanced diapsid reptiles," Rieppel concluded. Modern-day snakes and lizards also evolved from the diapsid population.
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