Morphological variation and craniofacial allometry in feliform carnivorans

With over 260 recognized extant species, the order Carnivora is one of the most diverse mammalian groups today, with a history tracing back approximately 60 million years. Crown carnivorans are divided into two suborders: Feliformia (cats, genets, hyenas, mongooses, etc.) and Caniformia (dogs, bears, raccoons, weasels, skunks, seals, etc.). Among the evolutionary trends shaping phenotypic diversity over macroevolutionary scales, Craniofacial Evolutionary Allometry (CREA) describes a pattern in which smaller species tend to have proportionally shorter faces and larger braincases. CREA has been documented in two caniform families (Canidae and Mustelidae) and one feliform family (Herpestidae), but not in Felidae. While feliforms generally exhibit shorter faces than caniforms, the reasons behind the felids’ deviation from the CREA pattern remain unclear. A large-scale study quantifying allometry in both fossil and living feliforms might provide key insights into this question.
We collected 3D landmark data from 112 specimens representing 49 species of extant and extinct feliforms and stem groups. Using 3D geometric morphometrics, we quantified cranial morphological variation and tested for allometric patterns within and across feliform families. Our preliminary results show weak allometric signals overall, with the strongest allometric relationship (highest adjusted R²) found in Felidae. Regressions of facial versus braincase size against centroid size were also weak. The lowest allometric signals are observed in Nimravidae and Viverridae, but are also very weak in Hyaenidae. hese preliminary results suggest that feliform carnivorans tend to deviate from the CREA pattern, highlighting the complexity of morphological disparity in Feliformia. As previously suggested in the literature, CREA is not universal, and the evolution of skull shape likely reflects a balance between functional adaptation (e.g., feeding ecology, ecological specialization) and developmental constraints, modularity, or evolutionary rates, which may obscure craniofacial allometry.