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The Taung endocast: A reply to Holloway
Author(s) -
Falk Dean
Publication year - 1983
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.1330600410
Subject(s) - endocast , anatomy , paleontology , geology , biology , skull
Indices of rostrality (i r , i r ′) are developed to assess the extent to which the medial end of the lunate sulcus (L) is rostrally positioned in photographs and figures of lateral views of primate brains and endocasts, and indices are determined for chimpanzees, SK 1585 and the Taung endocast. I r quantifies the extent of rostrality as it has traditionally been viewed (in A‐P projections) while i r ′ takes dorsal curvature into account. The i r of the feature that I have identified as the lunate sulcus of Taung is within one standard deviation of the mean i r for Pan and its i r ′ is within 1.5 standard deviations from the mean i r ′ for Pan. Both findings are compatible with my earlier statement that the medial end of the lunate sulcus of the Taung endocast is in a pongid‐like position. Use of stereoplotting to transfer the position of L from chimpanzee endocasts and brains to australopithecine endocasts is critically assessed: Holloway stereoplotted five chimpanzee brains and then transferred their mean coordinates that describe the lunate sulcus to the Taung endocast. If stereoplotting successfully transfers the extent to which L is rostrally located, one would expect the mean L of Pan and its transferred counterpart in Taung to have identical index values of rostrality. However, the i r of the lunate sulcus that Holloway located on Taung is over two standard deviations lower than the mean i r for the five chimpanzees he stereoplotted to determine its angular coordinates, and Holloway's i r ′ for Taung is one standard deviation lower than the five chimpanzees' mean i r ′. These discrepancies are shown to be due to shape differences, and it is concluded that stereoplotting should not be used to transfer sulci between differently shaped endocasts without correcting for these differences. I also reply to Holloway's criticisms of my use of L/H indices, palpation, techniques for sampling endocasts, and illustration of the Taung endocast. It is shown that there is room on the Taung specimen for the lateral end of L, and the pongid‐like sulcal pattern of Taung is reaffirmed. Thus, we do not yet know when human‐like sulcal patterns first appeared in the hominid fossil record.