Tempral fenestrae
The image illustrates the differences in the skulls and temporal fenestrae of anapsids, synapsids, and diapsids. Anapsids have no openings, synapsids have one opening, and diapsids have two openings.
Source
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"OpenStax College, Reptiles. October 17, 2013."
http://cnx.org/content/m44689/latest/Figure_29_04_02.jpg
OpenStax CNX
CC BY 3.0.
