Michael S. Yuan

The Human Fossil Record

Brain Endocasts is the only comprehensive, single-volume work dealing exclusively and uniformly with fossil hominid brain endocasts. Never-beforepublished photographs come together with easily accessible, coherent descriptions to create a detailed reference on the paleoneurological evidence for human evolution. Each entry offers essential information related to the location, dating, associations, and morphology of a given endocast. The text also covers the latest methodologies and techniques available for studying endocasts. In addition, a concise summary shows how these fossil records contribute to our understanding of human evolution and behavior.

Endocast of Sambungmacan 3 (Sm 3): a new Homo erectus from Indonesia.

A new fossil calvaria, Sambungmacan 3 (Sm 3), described in New Fossil Hominid Calvaria From Indonesia—Sambungmacan 3 by Márquez et al., this volume, yields one of the most advanced and complete endocasts yet recovered from Java. This communication provides a thorough interpretation of the external anatomical landmarks observable on Sm 3. Using computer tomography (CT) and traditional morphological measurements, our comparative paleoneurological analyses show that while Sm 3 has a mosaic of features that are similar to both Indonesian and Chinese H. erectus, it also possesses significant characters reminiscent of later hominins. These include a greater degree of asymmetry characterized by a possible left‐occipital, right‐frontal petalial pattern, left‐right volumetric cerebral asymmetry, and marked asymmetry in Brocas cap. Moreover, the frontal lobe offers a more rounded, shortened appearance in contrast to the flat, elongated appearance of other Indonesian fossils (e.g., Sangiran 17). Another unique trait is exhibited in the transverse plane where the widest breadth of Sm 3 occurs more superiorly than in other Indonesian H. erectus. Thus, the endocast of Sm 3 presents a unique morphology not seen previously in the hominin fossil record. While the strong modern human characteristics in this endocast may not represent a particular ancestry, they do allow us to recognize a new dimension of the remarkable variation in Indonesian Homo erectus. Anat Rec 262:369–379, 2001.

Missing Omo L338y‐6 occipital‐marginal sinus drainage pattern: Ground sectioning, computer tomography scanning, and the original fossil fail to show it

The Omo L338y‐6 occipital region has been recently studied by White and Falk ( 1999 ), who claim that it shows a readily identifiable enlarged left occipital‐marginal sinus (O/M). These observations are contrary to the direct observations of previous investigators (Rak and Howell, 1978 ; Kimbel, 1984 ; Holloway, 1981 ; Holloway, 1988 ). White and Falk ( 1999 ) further argue that the presence of this enlarged O/M strongly suggests that the Omo L338y‐6 hominid was indeed a “robust” Australopithecus. We used direct sectioning and CT scanning to analyze magnified sections of a high‐quality first‐generation cast of the newly cleaned original fossil. These methods fail to show any evidence of a morphological landmark that can be interpreted as an enlarged O/M, either as an eminence or a sulcus. In contrast, the same techniques used with both SK 1585 and OH5 (“robust” Australopithecus with an enlarged O/M) show extremely visible and palpable enlarged O/Ms. Examination of the original Omo fossil confirms that it lacks an O/M. This evidence clearly shows that an enlarged O/M cannot be identified on either the original fossil or a first‐generation cast, although this does not rule out the possibility that the Omo L338y‐6 hominid was a “robust” Australopithecus. We believe that the differences between observers regarding this feature are most probably due to displacement caused by a crack and the different source materials employed, i.e., the difference between a first‐generation cast of the original fossil and a third‐ or fourth‐generation cast of the endocast made two decades ago. Anat Rec 266:249–257, 2002.

Erratum: Missing Omo L338y-6 occipital-marginal sinus drainage pattern: Ground sectioning, computer tomography scanning, and the original fossil fail to show it (Anatomical Record (2002) 266 (249-257))

Holloway RL, Yuan MS, Broadfield DC, Degusta D, Richards GD, Silvers A, Shapiro JS, and White TD. Missing Omo L338y-6 occipital-marginal sinus drainage pattern: ground sectioning, computer tomography scanning, and the original fossil fail to show it. Anat Rec 2002:266:249 257.