An infratemporal

fenestra A fenestra (fenestration; plural fenestrae or fenestrations) is any small opening or pore, commonly used as a term in the biological sciences. It is the Latin word for "window", and is used in various fields to describe a pore in an anatomical st ...

, also called the lateral temporal fenestra or simply temporal fenestra, is an opening in the skull behind the orbit in some animals. It is ventrally bordered by a

zygomatic arch In anatomy, the zygomatic arch, or cheek bone, is a part of the skull formed by the zygomatic process of the temporal bone (a bone extending forward from the side of the skull, over the opening of the ear) and the temporal process of the zygomat ...

. An opening in front of the eye sockets, conversely, is called an

antorbital fenestra An antorbital fenestra (plural: fenestrae) is an opening in the skull that is in front of the eye sockets. This skull character is largely associated with archosauriforms, first appearing during the Triassic Period. Among extant archosaurs, birds ...

. Both of these openings reduce the weight of the skull. Infratemporal fenestrae are commonly (although not universally) seen in the fossilized skulls of dinosaurs. Synapsids, including mammals, have one temporal fenestra, while

sauropsids Sauropsida ("lizard faces") is a clade of amniotes, broadly equivalent to the class Reptilia. Sauropsida is the sister taxon to Synapsida, the other clade of amniotes which includes mammals as its only modern representatives. Although early syn ...

, the birds and reptiles, have two.

References

{{ref list Dinosaur anatomy Foramina of the skull