Anapsida
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(ə′nap·sə·də)
(vertebrate zoology) A subclass of reptiles characterized by a roofed temporal region in which there are no temporal openings.
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A subclass of reptiles characterized by a roofed temporal region in which there are no temporal fenestrations. Chelonia (turtles), with living representatives, and the extinct Cotylosauria are the two major subdivisions of this subclass. The Mesosauria, an extinct group of aquatic reptiles from the early Permian, have been included, but the assignment is far from certain.
Among the cotylosaurs are found the most primitive known reptiles, which date from the Early Pennsylvanian. These forms and their immediate descendants flourished in the Permian and Triassic periods of the late Paleozoic and early Mesozoic eras, respectively. Turtles first appear as fossils in Triassic rocks and are well represented in the fossil record from that time to the present. Throughout their history anapsids have, for the most part, inhabited areas close to water, with some exceptions among the turtles, and many of them have been semiaquatic in habitat and adaptations. See also Mesosauria.
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Anapsida
IN BRIEF: n. - Oldest known reptiles: turtles.
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McGraw-Hill Dictionary of Scientific and Technical Terms. Copyright © 2003, 1994, 1989, 1984, 1978, 1976, 1974 by McGraw-Hill Companies, Inc. All rights reserved.
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