anapsid

[uh-nap-sid]
adjective
  1. belonging or pertaining to the Anapsida, a subclass of reptiles, extinct except for the turtles, characterized by having no opening in the temporal region of the skull.
noun
  1. a reptile of the subclass Anapsida.
Compare diapsid.

Origin of anapsid

1930–35; < New Latin Anapsida, equivalent to an- an-1 + -apsida, plural of -apsidum, neuter adj. derivative of Greek apsís, hapsís loop, arch (referring to the opening in the skull); see apsis
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

anapsid in Science

anapsid

[ə-năpsĭd]
  1. Any of a group of mostly extinct reptiles having a skull with no temporal openings. Anapsids first appeared in the Permian Period. Modern turtles and tortoises may be surviving members of this group, or they may be descendants of diapsids that lost their skull openings. Compare diapsid synapsid therapsid.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.