| Gorilla

Gorilla

Gorillas are the largest extant species of primates. They are ground-dwelling, predominantly herbivorous apes that inhabit the forests of central Africa. Gorillas are divided into two species and either four or five subspecies...

 > | P. walkeri
(KNM-WT 17000) > | P. boisei

Paranthropus boisei

Paranthropus boisei was an early hominin and described as the largest of the Paranthropus species...

(KNM-ER 406) > | Dryopithecus

Dryopithecus

Dryopithecus was a genus of apes that is known from Eastern Africa into Eurasia during the late Miocene period. The first species of Dryopithecus was discovered at the site of Saint-Gaudens, Haute-Garonne, France, in 1856...

(RUD 77) > | Sahelanthropus
(TM 266-01-060-1) > | Australopithecus

Australopithecus

Australopithecus is a genus of hominids that is now extinct. From the evidence gathered by palaeontologists and archaeologists, it appears that the Australopithecus genus evolved in eastern Africa around 4 million years ago before spreading throughout the continent and eventually becoming extinct...

 > | P. robustus

Paranthropus robustus

Paranthropus robustus was originally discovered in Southern Africa in 1938. The development of P. robustus, namely in cranial features, seemed to be aimed in the direction of a "heavy-chewing complex"...

 > | Homo habilis

Homo habilis

Homo habilis is a species of the genus Homo, which lived from approximately at the beginning of the Pleistocene period. The discovery and description of this species is credited to both Mary and Louis Leakey, who found fossils in Tanzania, East Africa, between 1962 and 1964. Homo habilis Homo...

(OH 24, KNM-ER 1813) > | K. rudolfensis > | H. ergaster

Homo ergaster

Homo ergaster is an extinct chronospecies of Homo that lived in eastern and southern Africa during the early Pleistocene, about 2.5–1.7 million years ago.There is still disagreement on the subject of the classification, ancestry, and progeny of H...

 > | Pongo > | Pan > | Praeanthropus

Praeanthropus

Praeanthropus is a genus used by some researchers to include certain hominid species generally included in other genera by most researchers. The type species is Praeanthropus africanus, a defunct synonym of Praeanthropus afarensis...

 > | Homo sapiens >

Post-orbital constriction for various hominids

Increased constriction
0.57
0.57
0.57
Intermediate
0.73
0.59
0.66
0.70
0.72
0.70
0.75
0.66
0.70
Reduced constriction
0.80
Absolutely reduced constriction
0.92

In physical anthropology

Physical anthropology

Biological anthropology is that branch of anthropology that studies the physical development of the human species. It plays an important part in paleoanthropology and in forensic anthropology...

, post-orbital constriction is a narrowing of the cranium (skull) just behind the eye sockets (the orbits, hence the name), in primates — including primitive hominids. This constriction is very noticeable in non-human primates, slightly less so in Australopithecines, even less in Homo erectus

Homo erectus

Homo erectus is an extinct species of hominid that lived from the end of the Pliocene epoch to the later Pleistocene, about . The species originated in Africa and spread as far as India, China and Java. There is still disagreement on the subject of the classification, ancestry, and progeny of H...

 and the most primitive Homo sapiens. It completely disappears in modern Homo sapiens. Thus, it is a useful, quantifiable measure of how far along the evolutionary path a hominid fossil might be placed.

Post-orbital constriction is defined by an index of minimum frontal breadth (MFB) behind the supraorbital torus divided by maximum upper facial breadth (bifrontomalare temporale, BFM). For extant hominids the index value ranges from 0.46 to 0.8, with a mean index vaule of 0.66.