The supratemporal bone is a paired
cranial bone present in many
tetrapods and
tetrapodomorphfish.[1] It is part of the temporal region (the portion of the skull roof behind the eyes), usually lying medial (inwards) relative to the
squamosal and lateral (outwards) relative to the
parietal and/or
postparietal. It may also contact the
postorbital or
intertemporal (which lie forwards), or
tabular (which lies backwards), when those bones are present.[2]
The supratemporal is a common component of the skull in many extinct
amphibians, though it is apparently absent in the lightweight skulls of living
lissamphibians (frogs and salamanders).
Embryological studies of
salamanders suggests that the supratemporal fuses with the squamosal in early development.[3] A separate supratemporal was retained by early
synapsids and
reptiles, but was strongly reduced in many groups.
Squamates (lizards and snakes) still possess a small supratemporal, though
archosaurs (
crocodilians and
birds) and
mammals lack it. Some extinct
turtle relatives (like Proganochelys and Eunotosaurus) have a prominent supratemporal, but it is absent or fused to adjacent bones in modern turtles.[4][5]