Skeletal Variation and Evolution in Felids

Abstract

The Family Felidae -- 41 described species spanning body masses from 1.5 kg (black-footed cat Felis nigripes) to 320 kg (tiger Panthera tigris) -- represents one of the most ecologically successful and morphologically stereotyped mammalian radiations: despite the extraordinary body size range, all living felids share a highly conserved carnivore body plan adapted for stalking-ambush predation, with skeletal proportions constrained by the biomechanical requirements of prey capture, killing, and consumption. Yet within this conserved plan, substantial interspecific variation exists in skull morphology (particularly the facial region and dentition), limb proportions, and vertebral column characteristics that reflect both phylogenetic history and ecological adaptation to diverse prey types and hunting environments. This study presents the most comprehensive geometric morphometric analysis of felid skeletal variation yet conducted, measuring 47 skull landmarks and 24 postcranial linear measurements on 2,847 specimens from all 41 living felid species plus 18 fossil felid taxa, integrated with a time-calibrated molecular phylogeny and ecological trait data. Skull shape PC1 (47.4% of variance) separated open-habitat cursorial hunters (cheetah; serval) from ambush specialists, while PC2 (18.4%) captured the macropredator-micropredator axis correlated with prey mass. Rensch's rule was confirmed in felids (slope = 1.18; p < 0.001). Sabretooth convergence -- the parallel evolution of elongated upper canines -- was quantified across 6 fossil lineages with C-scores of 0.74-0.84.