ABSTRACT
Bone ornamentation consists of regular sculptural patterns on the outer surface of dermal bones in vertebrates. The first occurrence of this feature traces back to the Paleozoic and might have been linked to the regression of cosmine in early vertebrates, when the odontodes were replaced by bony tubercules forming repetitive reliefs on bone surface. The phenotypic expression of bone ornamentation persisted in nonteleost actinopterygians, stem tetrapods and stem amphibians but was lost in other taxa, although some teleosts and crown tetrapods secondarily evolved bone sculpture during the Mesozoic. Bone ornamentation may result either from local differences in accretion rate or from a specific (imbalanced) remodeling pattern on the outer cortex of dermal bones. The function of this feature has been debated. Recent studies in crocodylomorphs supported the existence of a link between ecophysiological adaptations, i.e., heat transfers during basking and probably also acidosis buffering during long apnea, and bone ornamentation, via the superficial vascular networks located between the sculptural reliefs. Further investigations are needed to understand the actual role(s) of bone ornamentation in species adaptations and evolution.
