Meeting Abstract
The study of locomotion in extant crocodylians is important because they are unusual reptiles with a mix of ancestral and derived traits, and because these traits provide insight into the evolution of locomotion in the broader archosaur lineage. Extant crocodylians show a unique ability amongst extant archosaurs by using a spectrum from more sprawling to more erect postures as well as a wide range of symmetrical and asymmetrical gaits. Ten young Nile crocodiles (Crocodylus niloticus) ranging from 1.5-7kg were filmed using a combination of light video and fluoroscopy (XROMM) to analyse their locomotion at a range of speeds and gaits, in both straight lines and around bends. These data were supplemented with kinetic measurements from force platforms. We found that the Nile crocodiles showed a range of postures at slow speeds, using a combination of sprawling ‘low walks’ and belly slides, as well as upright ‘high walks’; as in alligators. However, no matter the posture, the duty factor decreased significantly across the range of speeds from 0.1 to 0.7m/s (P < 0.01), with no significant difference between fore- and hindlimb duty factors. Our study provides an extensive new dataset on Nile crocodile locomotor dynamics, amplifying our understanding of archosaur locomotion.
