A morphometric and taxonomic assessment of a hominine femur from the lower member, Koobi Fora, Lake Turkana.

Abstract

Previous research by this author and others has indicated that species-level differentiation within the hominines can be detected in the femur. The femoral shaft of Homo erectus, relative to H. sapiens, demonstrates small anteroposterior diameters, a distally placed point of minimum shaft breadth, and increased cortical thickness resulting in medullary stenosis. This pattern has been identified in specimens from Choukoutien (I and IV), Olduvai (OH 28), and Lake Turkana (KNM ER 737). Findings reported here include anatomical comparisons and univariate and multivariate analyses based on external and internal shaft morphology. These results indicate that the femoral pattern characteristic of H. erectus can be identified in KNM ER 1481a recovered at Lake Turkana below the KBS tuff. Recent dating of that tuff indicates a date of ca. 1.8 mya, thereby yielding a date for KNM ER 1481a of congruent to 2.0 mya. Known H. erectus femora extend over a broad span and yet show very low variability; this pronounced stasis would strongly suggest that, at least in this portion of the postcranium, H. erectus was in a period of profound morphological stasis.