Crocodylians exhibit a high degree of cranial variation and convergence throughout their 80 million-year fossil record. Despite extensive investigation, discrepancies between morphological and molecular phylogenies persist and relate to taxa that share a slender cranial morphology believed to reflect ecological or functional specialization. Using geometric morphometrics to summarize morphological shape in crocodilian skulls, this project creates the first 3-D crocodylian skull morphology database of all 23 extant crocodylian post-hatchling ontogenies and fossil taxa from national and international collections. Analyses of this database will: 1) test the validity of current crocodylian cranial morphology and their relationship to phylogeny, 2) determine how skull shape distributions are ontogenetically and phylogenetically related, 3) determine relationships between morphological plasticity and ontogenetic environment by testing for skull shape differences between wild and farmed alligator specimens through their ontogeny. This research will provide insights into patterns and processes underlying morphological evolution and help to understand the discrepancy between molecular and morphological phylogenetic hypotheses for crocodylians. The database generated through this project will serve as a benchmark for testing hypotheses beyond the objectives of this proposal.
