The ''postorbital'' is one of the bones in

vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...

skulls which forms a portion of the dermal

skull roof The skull roof or the roofing bones of the skull are a set of bones covering the brain, eyes and nostrils in bony fishes, including land-living vertebrates. The bones are derived from dermal bone and are part of the dermatocranium. In com ...

and, sometimes, a ring about the orbit. Generally, it is located behind the

postfrontal 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 ...

and posteriorly to the

orbital fenestra The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

. In some vertebrates, the postorbital is fused with the postfrontal to create a postorbitofrontal. Birds have a separate postorbital as an

embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...

, but the bone fuses with the frontal before it hatches.

References

* Roemer, A. S. 1956. ''Osteology of the Reptiles''. University of Chicago Press. 772 pp. Skull bones {{Vertebrate anatomy-stub