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

Ralph L. Holloway, Michael S. Yuan, Douglas C Broadfield, David Degusta, Gary D. Richards, Adam Silvers, Jill S. Shapiro, Tim D. White

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

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/M's. 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.

Original languageEnglish (US)
Pages (from-to)249-257
Number of pages9
JournalAnatomical Record
Volume266
Issue number4
DOIs
StatePublished - Apr 1 2002
Externally publishedYes

Fingerprint

Fossils
tomography
sinuses
Drainage
drainage
fossils
Tomography
Hominidae
Occipital Lobe
Research Personnel
methodology

Keywords

  • Australopithecus
  • Brain endocasts
  • Brain evolution
  • Computer tomography
  • Drainage pattern
  • Ground sectioning
  • Occipital-marginal sinus (O/M)

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Anatomy

Cite this

Missing Omo L338y-6 occipital-marginal sinus drainage pattern : Ground sectioning, computer tomography scanning, and the original fossil fail to show it. / Holloway, Ralph L.; Yuan, Michael S.; Broadfield, Douglas C; Degusta, David; Richards, Gary D.; Silvers, Adam; Shapiro, Jill S.; White, Tim D.

In: Anatomical Record, Vol. 266, No. 4, 01.04.2002, p. 249-257.

Research output: Contribution to journalArticle

Holloway, Ralph L. ; Yuan, Michael S. ; Broadfield, Douglas C ; Degusta, David ; Richards, Gary D. ; Silvers, Adam ; Shapiro, Jill S. ; White, Tim D. / Missing Omo L338y-6 occipital-marginal sinus drainage pattern : Ground sectioning, computer tomography scanning, and the original fossil fail to show it. In: Anatomical Record. 2002 ; Vol. 266, No. 4. pp. 249-257.
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