Meeting Abstract
Archosaurian reptiles (including living crocodiles and birds) have had an explosion of locomotor variation since the Triassic. Their appendicular muscle physiology and biomechanics are pivotal to our understanding of how their diversity, natural history and evolution relate to this locomotor variation. Information on muscle contraction velocity, force and power in extinct archosaurs such as Pseudosuchia and Ornithodira is of course not available from fossil material, but is needed for biomechanical modelling and simulation. However, an approximation or range of potential parameter values can be obtained by studying extant representatives of the archosaur lineage. Here, we perform a quantitative study of the physiological performance of multiple muscles from several individuals of Nile crocodile (Crocodylus niloticus) and Elegant crested tinamou (Eudromia elegans). Nile crocodile musculature shows high power and velocity values– the FTI4, a small “hamstring” hip extensor and knee flexor actively used for terrestrial locomotion, performs particularly well. The Elegant crested tinamou muscles’ performance is on par with birds of similar body mass, and shows the same pattern of parameter variation between muscles of a similar function in other birds. These findings demonstrate physiological differences between anatomical muscles, potentially based on their roles during locomotion. By contributing new data from previously unstudied archosaurian species and muscles to existing data, we can now better bracket possible muscle parameter values, and thereby better estimate in computational analyses how extinct archosaurs may have moved.
