Brain endocast confirms hominid status for Sahelanthropus

[RichTravsky]

http://meeting.physanth.org/program/2013/session16/bienvenu-2013-the-endocast-of-sahelanthropus-tchadensis-the-earliest-known-hominid-7-ma-chad.html

The endocast of Sahelanthropus tchadensis, the earliest known
hominid (7 Ma, Chad)

Fossil remains assigned to Sahelanthropus tchadensis were found in the
Toros-Menalla fossiliferous area (Djurab Desert, Northern Chad), in
continental sediments dated to 7 Ma by both radiochronologic and
biochronologic methods. These fossils, including the famous male
holotype cranium TM 266-01-060-1 nicknamed Toumaï, display a number of
derived cranial and dental characters, making Sahelanthropus tchadensis
the earliest known hominid (= sister group of Panids) species.

Fossil hominid endocasts are the only direct evidence of human brain
evolution. The endocast of TM 266-01-060-1 opens a unique window on the
first steps of this evolution just after the split between humans and
chimpanzees. As the cranium is filled with highly mineralized matrix,
and the inner table of cranial bone is fragmented and distorted,
classical methods of endocast extraction could not be applied. Thus, a
special protocol was developed for this cranium, involving 3D X-ray
synchrotron microtomography, propagation phase contrast, semi-automated
segmentation of the inner table, and correction of postmortem distortion
based on both rigid and thin-plate spline transformations. The
reconstructed endocast of TM 266-01-060-1 is compared with older fossil
anthropoid endocasts, modern endocasts (great apes and humans) and
australopithecine endocasts, taking volumetric, linear and angular
measurements and performing a Generalized Procrustes Analysis.

The endocranial volume of TM 266-01-060-1 confirms the data (360-370
cc) already published for the 3D cranium reconstruction. It falls
within the variability range of chimpanzees. The studies are still in
progress, but numerous features of the brainstem, occipital lobes, and
prefrontal cortex, already confirm the hominid status of Sahelanthropus
tchadensis.

[Claudius Denk]

On Jun 2, 6:45 pm, RichTravsky <traRvEskyM...@hotmail.com> wrote:
> http://meeting.physanth.org/program/2013/session16/bienvenu-2013-the-...

Seven million years ago!

[JTEM]

RichTravsky <traRvEskyM...@hotmail.com> wrote:


> Fossil hominid endocasts are the only direct evidence of human brain
> evolution. The endocast of TM 266-01-060-1 opens a unique window on the
> first steps of this evolution just after the split between humans and
> chimpanzees.

This is a rather bold (wild, unsubstantiated) claim...

Not to mention one contradicted by their own genetic
evidence.


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