High density 3D morphometrics on Cretaceous marine predator teeth

Abstract

When it comes to study marine reptile ecology, the most efficient way to perform it is to study the most common fossil remains that are available. Those are the teeth. Massare’s triangle is certainly the first thing that comes to mind for anyone who has worked with marine reptile teeth. Her paper from 1987 was a milestone in marine reptile palaeontology and is still a reference nowadays. However, the method used to build the triangle includes a part of subjectivity that can be problematic and generate debates around the relevance of the different morphoguilds she established. A fully quantitative canvas for teeth shape analysis is proposed in this work. The objective is to develop a method based only on quantitative parameters and excluding qualitative and subjective ones. The method chosen to acquire the 3D data is the photogrammetry which gives precise 3D models that can be used to study shape variance with the help of computing power. Geometric morphometrics was used to quantify shape variations using GPA (Generalised Procrustes Analysis) and PCA (Principal Component Analysis). The results are displayed in morphospaces and are compared with Massare’s morphoguilds and some proposed by various authors that covered the subject of marine vertebrate dental morphologies.