NEWS

January 2018

The Society for Integrative and Comparative Biology (SICB), Annual Conference 2018

Abstract: Dr Andrew Cuff

 139-8  Sunday, Jan. 7 15:15 – 15:30  Ontogenetic changes in the body plan of the sauropodomorph Mussaurus and their implications for locomotion CUFF, AR*; OTERO, A; ALLEN, VA; MICHEL, KB; SUMNER-ROONEY, L; POL, D; HUTCHINSON, JR; Royal Veterinary College, UK; Museo de La Plata, Argentina; Royal Veterinary College, UK; Royal Veterinary College, UK; Oxford University Museum of Natural History, UK; Museo Paleontológico Egidio Feruglio, Argentina; Royal Veterinary College, UK acuff@rvc.ac.uk

Mussaurus patagonicus is a sauropodomorph from the Early Jurassic of Argentina, originally described from hatchling remains. Further discoveries of juvenile and mature specimens provide a sufficiently complete series to reconstruct general patterns of ontogeny. Here, one each of hatchling, juvenile (~1 year old), and adult (8+ years old) individuals was studied. Digital models of the bones were created for each specimen, from segmented μ-CT scans for the smaller bones and photogrammetry and laser scans for the larger bones. Modelled bones were then articulated to produce complete skeletons, with missing bones being replaced by scaled versions of adults or closely related taxa. Each skeleton was wrapped in convex hulls and more anatomically realistic shapes, which were used to estimate body mass and centre of mass, and to conduct sensitivity analyses of these calculations. Our results show that Mussaurus rapidly grew from about 50g at hatching, to ~7kg at one year old, and reaching ~1540kg at adulthood. During this time the body’s centre of mass moved from a position in the mid-thorax to a more caudal position nearer the pelvis, consistent with a shift from quadrupedalism to bipedalism that might have occurred early in ontogeny in Mussaurus and other early sauropodomorphs. Our findings offer important new insights into the evolution of locomotion across Sauropodomorpha; consistent with a heterochronic shift to quadrupedalism near Sauropoda.

Abstract: Dr Krijn Michel

76-8  Saturday, Jan. 6 09:45 – 10:00  Locomotion in Nile crocodiles: Kinematic effects of speed and posture MICHEL, KB*; CUFF, AR; ALLEN, VA; HUTCHINSON, JR; Royal Veterinary College kmichel@rvc.ac.uk

 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.

Research news:

December 2017

We have published our first paper from the DAWNDINOS project, on the early sauropodomorph dinosaur Mussaurus‘s forelimb muscles and motions. Learn more about it in this blog post here, and watch the moving Mussaurus arms in the video below!

Shiny NeW XROMMMay 2017: Shiny new XROMM has just arrived at the RVC’s Structure and Motion Lab. The DAWNDINOS team are checking and calibrating our new XROMM machine in preparation for experimental data collection.