Meeting Abstract
The repeated evolution of hypercarnivorous lineages that specialize on vertebrate prey within Carnivora is generally characterized as a history of increasing evolutionary and functional constraints on the morphology of the skull and limbs. One functional system that is consistently modified in hypercarnivorous lineages are the carnassial teeth, which are elongated to form highly efficient shearing blades. The increasing specialization of carnassial teeth in hypercarnivores is expected to constrain carnassial diversity and lower rates of morphological evolution. To test this prediction across extant Carnivora as well as between the very different feliform and caniform suborders we compared morphospace occupation and phylogenetic rates of morphological evolution between hypercarnivorous lineages and all other carnivorans. Tooth morphology (upper P4 & lower M1) was captured by placing four homologous landmarks on the main cones and conulids of the occluding surfaces. Surprisingly we found very different evolutionary patterns between the upper and lower sub-units of the carnassial functional system. The upper carnassial evolves as predicted: hypercarnivores have lower rates of morphological evolution in P4 and feliform and caniform hypercarnivores cluster in a constrained region of morphospace. In contrast the morphospace of M1 reveals the sub-orders have achieved elongation through different means and the rates of morphological evolution within hypercarnivorous lineages are significantly higher than those within general feliforms or caniforms. We speculate that the faster rates within the lower carnassial of hypercarnivores may reflect a release of constraint on the crushing function of the M1.
