Three-dimensional digital imaging of the partial Australopithecus africanus endocranium MLD 37/38.
OBJECTIVE
MLD 37/38 is one of a handful of Australopithecus africanus specimens. The partial cranium (about 2.5 million years old) is filled with stone matrix. The frontal part of the endocranium and most of the face are missing. Based on medical imaging techniques (computed tomography), we aimed to create virtual 3-dimensional reconstructions separately for the ectocranium and endocranium, reconstruct missing parts based on intraspecific comparison, estimate the endocranial capacity and describe endocranial morphological details that were physically inaccessible before.


METHODS
We mapped fossilized bone as distinct from stone matrix for every slice of the computed tomographic image, creating virtual endocasts. The missing endocranial parts were reconstructed, using thin-plate spline warping, from a reference specimen (STS 5, a complete A. africanus cranium). In contrast with previous studies, a large number of landmarks (8 anatomical and 455 semi-landmarks) were used for this reproducible reconstruction.


RESULTS
The endocranial capacity of the original partial cranium is 382 cm3, and the estimated volume for the reconstructed braincase is 440 cm3. On the left side of the endocast, signs of the meningeal vessel system could be detected. Transverse and sigmoid venous sinuses are present in MLD 37/38, whereas an occipital-marginal sinus system could not be found.


CONCLUSIONS
The reconstructed endocranial capacity of MLD 37/38 lies within the range of other A. africanus specimens (428-515 cm3). In its dimensions, the endocast is similar to that of STS 5. The patterning of detected meningeal arterial branches resembles that of modern humans. The absence of an enlarged occipital-marginal sinus system is typical of A. africanus.
Neubauer
Simon
S
Institute for Anthropology, University of Vienna, Vienna, Austria.
Gunz
Philipp
P
Mitteroecker
Philipp
P
Weber
Gerhard W
GW
D000818:Animals; D002508:Cephalometry / Q000379:methods*; D005580:Fossils; D000882:Haplorhini / Q000033:anatomy & histology*; D049690:History, Ancient; D021621:Imaging, Three-Dimensional; D010163:Paleontology; D012886:Skull / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed