Abstract
A recently described Erpetopus trackway bearing unusual claw and belly-drag marks ostensibly indicates an obligatory sprawled posture and belly-walk in the locomotion of small captorhinids. Here, the ichnology of the blue-tongued skink (Tiliqua scincoides) is investigated in order to identify features of a trackway produced by a lizard in continuous belly-walk. Comparisons between T. scincoides and Erpetopus tracks tested whether the locomotory pattern observed for T. scincoides resembles that of small captorhinid track makers. Characteristic features of the T. scincoides track include: (1) a belly-dragging mark, (2) claw scratch marks produced during the early stance phase, and (3) claw drag marks produced by the forelimb during the swing phase. Trackway parameters did not correlate with track maker velocity, rendering inference of velocity for belly-dragging track makers problematic. This result was probably caused by increased substrate influence on locomotor speed because of belly contact with the ground. The track characteristics of T. scincoides match those recently described for Erpetopus and thus corroborate the notion of a similar pattern of locomotion for small captorhinids.
ACKNOWLEDGMENTS
The authors would like to thank Rommy Petersohn (Institut für Spezielle Zoologie und Evolutionsbiologie, Jena, Germany) for her support during the treadmill trials, as well as Achim Schwermann (Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Bonn, Germany), Vivian Allen (Institut für Spezielle Zoologie und Evolutionsbiologie, Jena, Germany) and Sebastian Voigt (Urweltmuseum GEOSKOP/Burg Lichtenberg (Pfalz), Germany) for constructive critiques on an earlier version of this manuscript. The comments of anonymous reviewers and the editor helped to further improve the manuscript.