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Bony ponticles of the atlas (C1) over the groove for the vertebral artery in humans and primates: Polymorphism and evolutionary trends
Author(s) -
Le Minor JeanMarie,
Trost Olivier
Publication year - 2004
Publication title -
american journal of physical anthropology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.146
H-Index - 119
eISSN - 1096-8644
pISSN - 0002-9483
DOI - 10.1002/ajpa.10270
Subject(s) - biology , gorilla , anatomy , homo sapiens , hylobates , evolutionary biology , zoology , pongo pygmaeus , hominidae , primate , cercopithecidae , biological evolution , genetics , paleontology , sociology , anthropology
The aim of this study was to ascertain the distribution in primates of the three possible bony ponticles over the groove for the vertebral artery (ventral, lateral, and dorsal ponticles), in order to attempt to understand the variants observed in humans and to ascertain possible evolutionary trends in primates. The material consisted of 393 atlases of extant nonhuman primates representative of 41 genera, and of 500 human atlases (dried bones of adults). For each atlas, we studied the existence and morphology of the ponticles, and the type of association of these three ponticles on a given side, which are theoretically of eight in number (types A–H). The occurrence of these ponticles varied from complete absence to constant presence, according to the genera and taxa of primates. The presence of each of these ponticles in primates can be interpreted as a primitive or plesiomorphic character, and their absence as a derived or apomorphic character. The strepsirhines‐platyrrhines‐cercopithecines group, presenting a predominant primitive pattern (type A), appeared to be separated from the colobines‐hominoids group, presenting predominant derived patterns (type C in colobines, Pongo pygmaeus , and Pan troglodytes , and the more derived type D in Hylobates , Gorilla gorilla , and Homo sapiens ). The last derived stage, corresponding to the disappearance of the three atlantal ponticles (type H), was only observed in some individuals in hominoids. A marked intraspecific polymorphism characterized the hominoids. The presence of lateral and dorsal ponticles in humans appeared to correspond to their persistence within the progressive disappearance of the atlantal ponticles, constituting an evolutionary tendency characteristic of primates and particularly of hominoid evolution. Am J Phys Anthropol, 2004. © 2004 Wiley‐Liss, Inc.