One of the most basic, but extremely difficult, questions that have occupied the minds of neontologists and paleontologists through the ages is: how are organisms different?

Given the wonderful diversity of forms that one can observe among living and fossil carnivores, this question prompted me to seek a more quantitative way of comparing shapes. I am using 2D geometric morphometrics analysis to distinguish groups of hyena and dog species which differ in their skull shape.

This technique involves photographing the sides of a skull specimen, and then specifying locations (anatomical landmarks) that are present across all the skulls examined.

These landmarks are useful in revealing changes in their relative positions using a mathematical method called relative warp analysis. The results show relative shape difference among different species in terms of their skull shape as represented by the landmarks,

the farther away two specimens are from each other, the more different they are in shape. For example, it takes a lot of cranial deepening and forward vaulting of the frontal region to "turn" a basal hyena Ictitherium into a huge bone-cracker Dinocrocuta.

The authoritative source for geometric morphometrics is the morphometrics research group at the State University of New York at Stony Brook.