Temporal fenestra

From Palaeos

Temporal fenestrae are bilaterally symmetrical openings (fenestrae) in the temporal (cheek) region of the amniote skull.

The earliest amniotes simply had a solid skull. During the Carboniferous and Permian seveal distinct clades developed openings, perhaps for the attahment of or to make room for larger jaw muscles (hence a stronger bite), and/or to lighten the skull.

The presence or absence of temporal fenestra has in the past been used in the taxonomic classification of reptiles, but is used less often now, because sometimes the opening is lost (e.g. Sauropterygia and Ichthyosaurs are diapsids in which the upper temporal fenestra has been (independently?) lost), or develops independently (e.g. Mesosaurs).

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