Temporal Pit

General information

The temporal pits , or temporal windows , are openings present in craniums of some amniotes. They reduce cranium considerably, but it allow also the insertion of muscles which actuate the Mandibule (the jaw lower). The contributions of the various bones to the edge of these windows varies according to the groups considered.

Various terms are used to classify craniums of amniotes, according to the number and the position of the temporal windows: anapside , synapside , euryapside and diapside . These terms are not used here from a phylogenetic , but only descriptive point of view . All these types of fenestration (including the absence of window) appeared by convergence in various groups. The groups are written with a capital letter to differentiate them from the types of temporal openings.

Types of temporal fenestration

Configuration anapside

No window is present in the posterior part of a cranium anapside . This type of cranium constitutes the state plésiomorphe (= ancestral) at the amniotes. This cranium closes is present at many fossil groups of sauropsides:

• mésosauridés
• Eunotosaurus (a parareptile resembling a tortoise vaguely)
• majority of the procolophonidés
• majority of the owenettidés
• the paréiasaures
• captorhinidés
• " protorothyridés " *
• the tortoises, which are currently the only ones to have a cranium closed

Configuration synapside

At some amniotes, the cranium is bored of a lower temporal window: it is about a configuration synapside . This configuration appeared with many recoveries, since it is present at:

• the Synapsides (from where their name; group to which belong the mammalian )
• the millerettidés
• the bolosauridés
• the lanthanosuchoïdés
• the nyctiphrurétidés
• the nyctérolétéridés
• Candelaria (a owenettidé)
• Procolophon (a procolophonidé)

Configuration diapside

A cranium of the type diapside is characterized by the presence of higher and lower temporal pits. This configuration is present at the Diapsides, even if the cranium of some became euryapside or anapside thereafter. Here are some selected representatives (current and fossil) whose cranium is of diapside type:

• the lépidosaures (of which the Sphenodon , the iguanas, the lizards, the monitors or the snakes)
• the crocodiles
• the ptérosaures
• the dinosaurs (to which the birds belong)

Configuration euryapside

The state euryapside only corresponds to the presence of higher temporal pits. This configuration is derived from the state diapside: the disappearance of the lower temporal pit was done in the second time at various groups. Previously, let us tax them following were gathered together in the " Euryapsida " *, but it is not currently any more the case:

• Araeoscelis (a araéoscélidien)
• Trilophosaurus (a archosauromorphe)
• the ichthyoptérygiens (of which the ichthyosaures)
• the sauroptérygiens (of which the placodontes, the nothosaures or the plésiosaures)

Human anatomy

At the human being, the temporal pit is an opening of the side face of the Crâne, limited by the side facet of the frontal bone, the lower part of the parietal , the scale of the temporal and the temporal part of the large wing of the sphénoïde, and where the temporal Muscle fits. This opening is of type synapside .

Related articles

• Anapsida
• Synapsida
• Diapsida
• Euryapsida