Morphometric analysis of Crocodylus porosus from the north coast of Arnhem Land, Northern Australia

Abstract

Utilizing measurements from 1354 C. porosus, we have derived formulae for predicting snout-vent length from 17 other attributes. The specific problem of predicting body size from an isolated head or skull is treated separately and some data are presented on proportional tissue loss in skull preparation. Sexual dimorphism was examined, and is demonstrated in interocular width, the width at the midpoint of the cranial platform, and the length of the tail. Discriminant analysis has been used to distinguish males from females on the basis of external measurements of both the whole animal and the isolated head. Hatchling C. porosus from Arnhem Bay and the Blyth River have longer heads than those from the Liverpool River. C. porosus from Sarawak have longer tails and are heavier than those from northern Australia. Predicting the maximum size of C. porosus from large skulls in museums is difficult because of variations in basic skull shape. The body size at which mandibular teeth protrude through the premaxilla is quantified.