Abstracts (first author)
New approach to old vertebrae – a morphometric comparison of Miocene and extant snakesPDF
Comparative morphological study of fossil and recent snakes is of key interest for taxonomic identification, paleobiological reconstructions and character evolution analyses. Snake fossil record is sparse, due to the low occurrence of fossilisation of delicate bone structures, especially in smaller species. The characters used in study of extant snake vertebrae are most often degraded in fossils – protruding structures or exposed surfaces get broken off or eroded. The focus of this study was to explore the usability of structures less prone to damage, located near the centrum and at the base of the neural arch. This approach would allow the inclusion of a larger number of specimens, which could not be studied by the classical approach. We analyzed fossil snake vertebrae from a rich mid-Miocene assemblage at Vračević locality, in the vicinity of Belgrade, Serbia. We selected a sample of undistorted trunk vertebrae in good condition, referred to genera Natrix, Vipera and Elaphe. The fossil sample was compared to extant snake vertebrae, belonging to appropriate taxa. Three axial and four pairs of lateral landmarks (11 landmarks in total) have been identified on all the specimens and used for 2D geometric morphometric analysis. Bilateral acquisition addressed the problem of taphonomic deformation. Symmetric component of shape variation was used for the comparison of fossil vertebrae with extant samples. Fossil specimens had lower mean centroid size (CS), and higher variation in CS compared to recent ones. The range of fossil CS values was larger than the recent (the smallest and largest vertebrae were fossils). Principal component analysis (PCA) showed that the highest variation in shape was associated with centrum/neural arch height ratio. For further research, more comprehensive sampling is needed to rigorously evaluate the applicability of this approach.