Why the short face? The face lengths of sthenurine kangaroos scale with negative allometry

The larger species in many mammalian clades have relatively longer faces than their smaller relatives. This has been shown to be true for extant kangaroos (Macropodinae), who follow the CREA rule of positive facial allometry; but the extinct short-faced kangaroos (Sthenurinae) have not so far been examined. Using linear measurements, rather than CREA techniques, we show here that sthenurine face lengths scale with negative allometry, thus differing from the trend seen in their extant relatives.