AbstractsAnthropology

The anterior inferior iliac spine (AIIS) is a consequential trait of interest in the study of hominid evolution by virtue of its role in being one of many traits often used to predict the locomotor condition of fossil taxa as well as the developmental differences that exist between humans and our closest living relatives. Descriptions of the AIIS in fossil taxa have recently been discussed in specimens such as Australopithecus sediba (1.95-1.78 mya), Ardipithecus ramidus (4.4 mya), and Oreopithecus bambolii (7-9mya), to name a few. In order to fully appreciate the AIIS as an informative anatomical character and its relevance to possible locomotor condition in other taxa, it is essential to understand it in Homo sapiens . Here, we examined the developmental process and morphology of the AIIS in hominids and its corresponding area in African apes as well as relative iliac isthmus breadth. We posit that the exuberant growth required to achieve the unique mediolateral expansion of the hominid iliac isthmus is ultimately responsible for the emergence of its novel apophysis, the AIIS. Furthermore, we propose that relative isthmus breadth can be reasonably used to determine the presence/absence of a true AIIS in extinct taxa for which there are no appropriate subadult specimens.