The postfrontal is a paired cranial bone found in many
tetrapods. It occupies an area of the skull roof between and behind the
orbits (eye sockets), lateral to the
frontal and
parietal bones, and anterior to the
postorbital bone.
The postfrontal forms part of the rear and upper border of the eye socket when present. It is particularly large in many extinct
amphibians and their
sarcopterygian (lobe-finned fish) ancestors, stretching forwards to contact the
prefrontal, thus separating the frontal from the rim of the orbit. In living amphibians (
lissamphibians), the postfrontal is absent, having failed to ossify during development.[1] The postfrontal is present but reduced in some reptiles, including modern
squamates (lizards and snakes). It is lost or fused to surrounding bones in
mammals,
crocodylomorphs[2] (including
crocodilians) and
dinosaurs (including birds),[3] though it is present in other extinct
archosaurs.
^Benton, Michael J.; Clark, James M. (1988). "8. Archosaur phylogeny and the relationships of the Crocodylia". In Benton, Michael J. (ed.). The Phylogeny and Classification of the Tetrapods, Volume 1: Amphibians, Reptiles, Birds. Oxford: Clarendon Press. pp. 295–338.