Conroy G C, Vannier M W, Tobias P V
Department of Anatomy and Neurobiology, Washington University Medical School, St. Louis, MO 63110.
Science. 1990 Feb 16;247(4944):838-41. doi: 10.1126/science.2305255.
The earliest hominid from South Africa, Australopithecus africanus, is known from only six specimens in which accurate assessment of endocranial capacity and cranial venous outflow pattern can be obtained. This places a severe limit on a number of hypotheses concerning early hominid evolution, particularly those involving brain-body size relationships and adaptations of the circulatory system to evolving upright posture. Advances in high-resolution two- and three-dimensional computed tomography (CT) now allow the inclusion of another important specimen to this list, MLD 37/38 from Makapansgat. A new computer imaging technique is described that "reconstructs" the missing portions of the endocranial cavity in order to determine endocranial capacity. In addition, CT evaluation allows assessment of cranial venous outflow pattern even in cases where the endocranial cavity is completely filled with stone matrix. Results show that endocranial capacity in this specimen is less than originally proposed and also support the view that gracile and robust australopithecines evolved different cranial venous outflow patterns in response to upright postures.
来自南非的最早原始人类南方古猿非洲种，仅通过六个标本为人所知，通过这些标本可以准确评估颅内容量和颅静脉流出模式。这对许多关于早期原始人类进化的假说造成了严重限制，尤其是那些涉及脑体大小关系以及循环系统对逐渐形成的直立姿势的适应的假说。高分辨率二维和三维计算机断层扫描（CT）技术的进步，现在使来自马卡潘斯盖特的另一个重要标本MLD 37/38也能加入这个名单。本文描述了一种新的计算机成像技术，该技术“重建”颅腔的缺失部分以确定颅内容量。此外，即使在颅腔完全被石基质填满的情况下，CT评估也能对颅静脉流出模式进行评估。结果表明，该标本的颅内容量比最初提出的要小，同时也支持了纤细型和粗壮型南方古猿为适应直立姿势而进化出不同颅静脉流出模式的观点。
