title: A quantitative assessment of bone area increase due to ornamentation in the Crocodylia.
abstract: Bone ornamentation, in the form of highly repetitive motives created by pits and ridges, is a frequent feature on vertebrate skull roofs and osteoderms. The functional significance of this character remains a matter of controversy and speculation. The many diverging hypotheses proposed to explain it all share a common logical prerequisite: bone ornamentation should increase significantly the surface area of the bones that bear it. In order to test this assumption in the Crocodylia, we developed a method for quantifying the gain in area due to ornamentation using a three-dimensional-surface scanner. On crocodylian osteoderms, the gain in area can be up to 40%, and on the cranial table, it ranges between 10 and 32% in adult specimens (in both cases, it shows substantial differences between the adults of the various species included in the sample). Area gain on the snout is lesser (0-20% in adults), and more variable between species. In general, bone ornamentation is less pronounced, and results in fewer area gains in juvenile specimens. The main morphometric results yielded by this study are discussed in reference to the few comparative data available hitherto, and to the functional interpretations proposed by previous authors.
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie (UPMC), UPMC Univ Paris 06, UMR 7193, Institut Des Sciences De La Terre Paris (ISTeP), 4 Place Jussieu, BC 19, Paris, F-75005, France.|CNRS, UMR 7193, Institut Des Sciences De La Terre Paris (ISTeP), 4 Place Jussieu, BC 19, Paris, F-75005, France.|Département Histoire De La Terre, Museum National D'histoire Naturelle, UMR 7207 (CR2P), Sorbonne Universités, Muséum National d'Histoire Naturelle (MNHN)/CNRS/UPMC, Bâtiment De Géologie Paris Cedex 05, F-75231, France.
authors.forename: François
authors.initials: F
authors.lastname: Clarac
authors.affiliation: Plateforme De Morphométrie Du MNHN -UMS 2700 Outils Et Méthodes De La Systématique Intégrative, 55 Rue Buffon, Paris, 75005, France.
authors.forename: Thibaud
authors.initials: T
authors.lastname: Souter
authors.affiliation: Institut De Systématique, Evolution, Biodiversité, ISYEB, UMR 7205, CNRS, MNHN, UPMC, EPHE, Muséum National D'histoire Naturelle, Sorbonne Universités, 57 Rue Cuvier 75005, Paris, France.
authors.forename: Raphaël
authors.initials: R
authors.lastname: Cornette
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie (UPMC), UPMC Univ Paris 06, UMR 7193, Institut Des Sciences De La Terre Paris (ISTeP), 4 Place Jussieu, BC 19, Paris, F-75005, France.|CNRS, UMR 7193, Institut Des Sciences De La Terre Paris (ISTeP), 4 Place Jussieu, BC 19, Paris, F-75005, France.
authors.forename: Jorge
authors.initials: J
authors.lastname: Cubo
authors.affiliation: Département Histoire De La Terre, Museum National D'histoire Naturelle, UMR 7207 (CR2P), Sorbonne Universités, Muséum National d'Histoire Naturelle (MNHN)/CNRS/UPMC, Bâtiment De Géologie Paris Cedex 05, F-75231, France.
authors.forename: Vivian
authors.initials: V
authors.lastname: de Buffrénil
mesh_terms: D000489:Alligators and Crocodiles / Q000033:anatomy & histology / Q000254:growth & development*; D000818:Animals; D001846:Bone Development
keywords: dermal bones; gain in area; osteoderms; pits; thermoregulation