Comparative Osteology in Small Felids: Evolutionary Implications

Abstract

Small felids represent the most species-rich yet least-studied radiation within Felidae, with their skeletal morphology and evolutionary history remaining incompletely characterised. This study conducted a systematic comparative osteological analysis of 18 small felid species across all eight lineages of the Felidae phylogeny, quantifying 42 postcranial and 24 cranial skeletal measurements from 1,284 museum specimens using geometric morphometrics and phylogenetic comparative methods. Procrustes ANOVA revealed significant effects of body mass (R2 = 0.38), primary prey size (R2 = 0.22), and locomotor habitat (arboreal vs. terrestrial; R2 = 0.18) on cranial shape, collectively explaining 78% of interspecific shape variance. Phylogenetic signal in cranial shape (Blomberg’s K = 0.62, p = 0.002) was moderate, consistent with substantial convergent evolution. PGLS regression identified relative orbit size, zygomatic arch width, and auditory bulla volume as the cranial traits most strongly associated with nocturnality, prey capture method, and acoustic environment. Postcranial osteometry confirmed significant elongation of distal limb elements in arboreal specialists relative to terrestrial counterparts. Early Burst model fitting was preferred over Brownian motion in six of eight felid lineages (DAIC > 4), indicating decelerating evolutionary rates consistent with early ecological opportunity exploitation. These findings provide a comprehensive osteological reference framework for small felid systematics and palaeontological specimen identification.