Crocodile Tooth Histology from a Pliocene Deposit in Chinchilla, Queensland

Abstract

Chinchilla in the Western Downs Region of Queensland is home to the Chinchilla Rifle Range, a palaeontological site that has produced a significant well-preserved Pliocene vertebrate assemblage. Here, we describe and discuss the histology of a crocodile tooth recovered from the ca 3.5-million-year-old Chinchilla Sand deposit in the Rifle Range. The tooth is from the posterior jaw and likely belongs to a species of Paludirex. We discuss the tooth micro-morphology in relation to what is known about tooth histology in extant and extinct crocodylians with brevirostine and platyrostral skull morphology. We hypothesised that there should be several similarities in the tooth micro-structures between related extinct and extant taxa. We found that the Chinchilla Sand fossil tooth is characterised by thin enamel that is likely prismless but shows incremental striations (also seen in dentine), similar to other crocodylians. This short study highlights the importance of microscopic techniques applied to fossil material. With further fossil evidence emerging from Chinchilla, and application of three-dimensional microscopy techniques to understand the nature of Paludirex enamel prisms, a better understanding of reptile palaeobiology can be developed for Queensland and Australia.