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 language | English (US) |
|---|---|
| Pages (from-to) | 249-257 |
| Number of pages | 9 |
| Journal | Anatomical Record |
| Volume | 266 |
| Issue number | 4 |
| DOIs | |
| State | Published - Apr 1 2002 |
| Externally published | Yes |
Fingerprint
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 journal › Article
}
TY - JOUR
T1 - Missing Omo L338y-6 occipital-marginal sinus drainage pattern
T2 - Ground sectioning, computer tomography scanning, and the original fossil fail to show it
AU - Holloway, Ralph L.
AU - Yuan, Michael S.
AU - Broadfield, Douglas C
AU - Degusta, David
AU - Richards, Gary D.
AU - Silvers, Adam
AU - Shapiro, Jill S.
AU - White, Tim D.
PY - 2002/4/1
Y1 - 2002/4/1
N2 - 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.
AB - 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.
KW - Australopithecus
KW - Brain endocasts
KW - Brain evolution
KW - Computer tomography
KW - Drainage pattern
KW - Ground sectioning
KW - Occipital-marginal sinus (O/M)
UR - http://www.scopus.com/inward/record.url?scp=0036533588&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0036533588&partnerID=8YFLogxK
U2 - 10.1002/ar.10067
DO - 10.1002/ar.10067
M3 - Article
C2 - 11920388
AN - SCOPUS:0036533588
VL - 266
SP - 249
EP - 257
JO - Anatomical Record
JF - Anatomical Record
SN - 1552-4884
IS - 4
ER -