Synchrotron X-ray microdiffraction to study dental structures in Cretaceous crocodylomorphs

Synchrotron radiation X-ray microdiffraction (SR-mu XRD) has been applied for the first time as a fundamental method of analysis to unveil crocodilian teeth growth and development. Teeth from a fossil crocodylomorph from the Upper Cretaceous site of Lo Hueco (Spain) and a modern crocodylian from the living species Crocodylus niloticus have been analysed. Both samples have been studied through Polarized Light Microscopy, Scanning Electron Microscopy coupled with Energy Dispersive X-Ray Spectroscopy, Confocal Raman Spectroscopy, and SR-mXRD. Significant differences have been found in hydroxyapatite (HA) crystallite sizes and texture, and the evolution of these two features along teeth depth. The main differences observed in crystallite size are related to postdepositional processes and/or the environmental and functional pressures of teeth during crocodylomorph life, very different from that of the modern specimen. Regarding the crystalline texture in the tooth enamel, it can be linked to teeth functionality during crocodilian life, causing the directed growth of HA crystallites due to the mechanical stress to which they are subjected. (C) 2021 The Authors. Published by Elsevier Ltd.

Automated summary

Synchrotron radiation X-ray microdiffraction has been applied for the first time to analyze the growth and development of crocodilian teeth. Significant differences in hydroxyapatite crystallite sizes and texture were found between a fossil crocodylomorph and a modern crocodylian, suggesting different postdepositional processes and functional pressures during their lives. The crystalline texture in the tooth enamel seems to be influenced by teeth functionality and mechanical stress during crocodilian life.