title: Morphological integration and functional modularity in the crocodilian skull.
abstract: We explored the morphological organization of the skull within Crocodylidae, analyzing functional and phylogenetic interactions between its 2 constituent functional modules: the rostrum and the postrostrum. We used geometric morphometrics to identify localized shape changes, focusing on the differences between the major clades of the crown-group Crocodylia: Alligatoridae and Crocodylidae. We used published bite performance data to correlate rostral function with postrostral morphology. The skull modules appear more integrated within Alligatoridae than within Crocodyliade. Phylogenetic effects on shape variation are more evident in Alligatoridae than in Crocodylidae, where functional parameters concerning the rostral morphology are proportionally more important than phylogeny. Long-snouted species are characterized by low structural performance, which is significantly associated with a reduction of the pterygoid-quadrate cranial nipper, suggesting that the nipper is important for the ingestion of large food items in generalist species. This functional association is coupled with a significant evolutionary allometry at the clade level, while Alligatoridae and Crocodylidae show different degrees of evolutionary allometry for their entire shape and rostrum. The postrostrum is more conservative than the rostrum in terms of morphospace occupation, evolutionary allometry and phylogenetic signal.
authors.affiliation: Pierre and Marie Curie University, Paris, France; Center for Evolutionary Ecology, Rome, Italy; Department of Sciences, 'Roma Tre' University, Rome, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Piras
authors.forename: Angela D
authors.initials: AD
authors.lastname: Buscalioni
authors.forename: Luciano
authors.initials: L
authors.lastname: Teresi
authors.forename: Pasquale
authors.initials: P
authors.lastname: Raia
authors.forename: Gabriele
authors.initials: G
authors.lastname: Sansalone
authors.forename: Tassos
authors.initials: T
authors.lastname: Kotsakis
authors.forename: Jorge
authors.initials: J
authors.lastname: Cubo
mesh_terms: D000489:Alligators and Crocodiles / Q000033:anatomy & histology*; D000818:Animals; D005075:Biological Evolution; D005580:Fossils; D015999:Multivariate Analysis; D010802:Phylogeny; D012886:Skull / Q000033:anatomy & histology*
keywords: crocodilian skull; functional performance; geometric morphometrics; modularity; morphological integration