Apples, oranges, and the lunate sulcus.

Area of Science:

• Paleoanthropology
• Primate Paleontology
• Comparative Anatomy

Background:

• The position of the lunate sulcus in australopithecine endocasts is debated.
• Previous research by Holloway (1984) aimed to resolve this by comparing Taung endocasts to chimpanzee brain casts.

Purpose of the Study:

• To re-evaluate Holloway's (1984) findings on the lunate sulcus position in the Taung endocast.
• To determine if Holloway's methodology, when applied correctly, supports or refutes the pongid-like position of the lunate sulcus in australopithecines.

Main Methods:

• Direct tape-arc measurements of the occipital pole-lunate sulcus (OP-LS) arc on the Taung endocast.
• Comparison of direct OP-LS arc measurements from Taung with Holloway's chimpanzee data.

Main Results:

• Holloway's original analysis of the Taung endocast did not directly measure the OP-LS arc.
• Direct measurement of the OP-LS arc on the Taung endocast places the lunate sulcus within the range observed in chimpanzees.
• Holloway's own methodology and data, when correctly applied, support a pongid-like lunate sulcus position in australopithecines.

Conclusions:

• Holloway's (1984) conclusion that the lunate sulcus is anterior in Taung is not supported by a direct application of his methods.
• The lunate sulcus in the Taung australopithecine endocast is located in a position comparable to that of pongids (apes).
• This finding supports the hypothesis of a pongid-like lunate sulcus position in australopithecines.