The posterior border of the sphenoid greater wing and its phylogenetic usefulness in human evolution

The elucidation of patterns of cranial skeletal maturation and growth in fo ssil hominids is possible not only through dental studies but also by mappi ng different aspects of ossification in both extant African apes and humans . However, knowledge of normal skeletal development in large samples of ext ant great apes is flimsy. To remedy this situation, this paper offers an ex tensive survey and thorough discussion of the ossification of the posterior border of the sphenoid greater wing. Indeed, this area provides much infor mation about basicranial skeletal maturation. We investigate three variants : the absence of the foramen spinosum and the position of both the foramen spinosum and the foramen ovale in relation to the sphenosquamosal suture. P roviding original data about humans and 1,425 extant great ape skulls and u sing a sample of 64 fossil hominids, this study aimed to test whether diffe rent ossification patterns occurred during the course of human evolution. The incidence of three derived morphologies located on the posterior border of the sphenoid greater wing increases during human evolution at different geological periods. The evolutionary polarity of these three derived morph ologies is assessed by outgroup comparison and ontogenetic methods. During human evolution, there is a clear trend for the foramen spinosum to be pres ent and wholly located on the posterior area of the sphenoid greater wing. Moreover, in all the great ape species and in Australopithecus afarensis, t he sphenosquamosal suture may split the foramen ovale. Inversely, the foram en ovale always lies wholly within the sphenoid greater wing in Australopit hecus africanus, robust australopithecines, early Homo, H. erectus (and/or H. ergaster), and Homo sapiens. From ontogenetic studies in humans, we conc lude that, during human evolution, the ossification of the posterior area o f the sphenoid greater wing progressively surrounded the middle meningeal a rtery (passing through the foramen spinosum) and the small meningeal artery (passing through the foramen ovale). Am J Phys Anthropol 107:387-399, 1998 . (C) 1998 Wiley-Liss, Inc.