Variation of the crocodilian chondrocranium

FERNANDEZ BLANCO, MARÍA VICTORIA; INGMAR WERNEBURG

Cairns, QLD

Congreso; 13th International Congress of Vertebrate Morphology; 2023

International Society of Vertebrate Morphologists

The chondrocranium is a primordial cartilaginous structure formed during the embryonic development of all vertebrates. Anatomical descriptions of it are scarce, especially for crocodilians. The chondrocranium acts as a scaffold for future skull formation, and information on its embryonic development is crucial for interpreting the homology of adult skull elements since cranial features have great systematic importance. Here, we present the preliminary results of a larger study whose main objective is to describe and quantify chondrocranial morphological variation among living reptiles. We want to test the hypothesis that morphology will be more similar in taxa with closer phylogenetic relationships. For this purpose, herein, using novel data and the available literature, we compared chondrocranial proportions of 13 crocodilian specimens belonging to two of the three major crocodilian taxa, Alligatoroidea and Crocodyloidea. Variation was assessed by a Principal Component Analysis (PCA) of a correlation matrix built on the chondrocranial proportions. As a result, PC1 and PC2 explain 76% of the total variance with nasal proportions contributing most to shape differences. Moreover, a phylogenetic pattern can be observed in the PCA, with the two main clades of Alligatoroidea (Caimaninae and Alligatorinae) more closely related to each other than to Crocodyloidea.