Meeting Abstract

S10-1  Thursday, Jan. 7 08:30  Reliving the past: The ontogeny and evolution of crocodylomorph feeding success GIGNAC, Paul M*; O\'BRIEN, Haley D; Oklahoma State University Center for Health Sciences; Ohio University

It is largely assumed that the functional anatomy of adult forms tightly fits the adult niche. At odds with this precept are groups with resource dependent growth, whose ontogenies seemingly recapitulate adult morphologies of ancestral taxa. Integrated developmental-evolutionary histories can constrain maturing phenotypes, so much so that deviations may negatively affect clade persistence. Here we study the development and evolution of the suchian feeding apparatus to assess the impact of such ontogenetic inertia on clade dynamics. Regardless of niche-specific rostrodental phenotypes, modern adult suchians (Crocodylia) are robust, high-force biters and often capable of subduing large prey. Neonatal forms, on the other hand, are reminiscent of early suchians with lower bite forces, delicate dentitions, and relatively short jaws. Using biomechanical and evolutionary modeling techniques we formally investigate the occurrence and impact of such shifts in suchia. We examine total-morphospace evolution, clade-wide disparity, and convergence on functional phenotypes between stages of crocodylian ontogeny and suchian evolution. Our findings show that developmental patterns appear to broadly mirror the increasing size and robustness of the suchian jaw during its 240 million year history. The generalist life histories of neosuchians, in particular, appear to exemplify such coordination; however, the ecomorphological specializations of notosuchians inversely demonstrate a decoupling of such histories, precipitating reduced clade longevity. Our findings, therefore, demonstrate how visiting historical phenotypes during ontogeny can contribute to functionally important morphologies that aid individual and clade success without being strongly tied to their adult niche.