Paranthropus face

The Paranthropus head is characterized by features traditionally thought to be related to heavy chewing. McCollum [Science 284 (1999) : 301-305] proposed that palatal thickening is a response to developmental integration between the mandibular ramus, oral and nasal functional matrices, and the vomer, which inserts onto the premaxilla in Paranthropus and causes the palate to thicken instead of rotate during vertical expansion. I tested whether palate thickness increases as a byproduct of differential increases in the sizes of the oral and nasal functional matrices compared to growth in the mandibular ramus. To do so, I collected 3D volume and landmark data from computed tomography (CT) scans of extant (Homo sapiens, Pan troglodytes, Gorilla gorilla, Pongo pygmaeus) and extinct taxa (Australopithecus and Paranthropus), and tested counterpart relationships for bones in the cranium using scaling analyses. Results suggest that developmental constraints related to growth counterpart relationships in the skulll are unlikely to affect palate thickness in the genus Paranthropus.