Studying dinosaurs has always been cool. But these days we can do even cooler stuff, creating detailed computer models to explore and understand fossils (e.g., here, here, here). I have to say that if I were an undergraduate today, I might very well be tempted to take this up as a field of study.
This fall researchers at Bristol report a study of fossil joints that illuminates the evolution of walking, standing, and running [1].
Dinosaurs and other ancient animals had a great variety of hip bone structures. Even closely related species have divergent designs, and families evolved over time. “the implications of these different morphologies for specific functions are still poorly understood.” ([1], p. 1)
The new study scanned two well preserved hip bones from Euparkeria capensis , a small dinosaur that lived during the early Middle Triassic, generally considered an ancestor of our favorite dinosaurs and their contemporaries. The fossils were scanned with micro CT imagery that enabled the bones to be discerned within the surrounding matrix. The resulting datasets had a resolution of smaller than a millimeter.
The data was assembled and loaded in the widely used Maya 3D modelling system. The data was processed to create high resolution 3D reconstructions of the bones.
Maya has extensive animation capabilities (for creating digital video and games), including simulations of skeletal and locomotion. These facilities were applied to the Euparkeria models to study potential pose and locomotion implied by the anatomy.
Cool!
The big question is just what angle were the legs—how “sprawly” was the stance? The analysis suggests that a fully erect, columnar pose is possible, as well as a range of moderately splayed postures. A fully crocodile-like sprawl seems unlikely, but possible. The researchers suggest that there are a combination of “ancestral” and new features, indicating the evolution of locomotion.
“Overall, Euparkeria demonstrates a mixture of ancestral and derived morphological traits, which is also reflected in the simulation results, indicating that the classical trend towards more adducted postures in archosaurs was rather complex, and less straightforward than previously thought” ([1], p. 8)
In particular, while the hip of Euparkeria might have supported erect locomotion, the requisite features of the ankles of evolved later.
Neat.
Maya is a really great bit of kit, but it was not really designed for paleontology. It goes to show that a good tool enables creativity beyond the original application.
- Oliver E. Demuth, Emily J. Rayfield, and John R. Hutchinson, 3D hindlimb joint mobility of the stem-archosaur Euparkeria capensis with implications for postural evolution within Archosauria. Scientific Reports, 10 (1):15357, 2020/09/21 2020. https://doi.org/10.1038/s41598-020-70175-y
- School of Biological Science, Modelling of ancient fossil movement reveals step in the evolution of posture in dinosaur and crocodile ancestors, in University of Bristol – School of Biological Science – News, September 21, 2020. http://bristol.ac.uk/biology/news/2020/modelling-of-ancient-fossil-movement.html
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