Modelling Dinosaurs With Computer Graphics Software

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.

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1. 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
2. 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

 

Robot Dinosaurs

I like robots.  I like dinosaurs.  So let’s do robots to study dinosaurs!

Or more specifically, let’s reverse engineer dinosaurs, to deduce details of their locomotion [2].  OK, technically, this ancient reptile is not necessarily a “dinosaur”, per se.  So what?

As we accumulate more and more dinosaur tracks and trackways [1], we learn more about how dinosaurs and other ancient animals lived (and here, here, here). Of course, there is often a disconnect, where we have skeletons with no known tracks, and tracks of unidentified specimens.  Actually, even for living species, it is difficult enough to deduce the reality of locomotion from skeletons and trackways—which is obvious because we can watch the animals actually move.

A new study this fall reports on a detailed study of an ancient species for which we have complete skeletons and trackways. Orobates pabsti lived about 260 millions years ago, and looks to me like a beefy, 1.5 meter long iguana [2].  This family is ancestors of reptiles, and its behavior is an indication of the evolutionary history of amphibians, reptiles, and everybody else.

The research used computational models of the mechanics of the skeleton and simulated musculature and physiology to examine plausible gaits for these animals [2].  This “design space” was further constrained by the trackways which were made by these animals when alive. (They have a neat interactive web page that shows how complicated the theoretical biophysics of walking is.) <<link interactive>>

In addition to the computational modelling, the researchers created a three dimensional model of the skeleton, and realized the model as a robotic Orobates. And then they made the OroBOT walk along 3D models of trackways, to show that the hypothesized gait is plausible.

“Using gaits suggested by the above-mentioned exclusion settings, the physical robot was capable of reproducing track- way parameters associated with Orobates “ ([2], p. 354)

Cool!

This research built on an earlier robot simulator of a salamander, which was adapted to study this ancient species.

Obviously, one could do this study with just computational models and visualizations. But creating the tangible robot is both esthetically pleasing and a form of reality check. No matter how careful and sophisticated the computational model, seeing an actual OroBOT walk proves that the hypothesized reconstruction is plausible.  And seeing it walk in the footprints of ancient Orobates is very convincing

Nice work

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1. Martin Lockley, Tracking Dinosaurs: A New Look At An Ancient World, Cambridge, Cambridge University Press, 1991.
2. John A. Nyakatura, Kamilo Melo, Tomislav Horvat, Kostas Karakasiliotis, Vivian R. Allen, Amir Andikfar, Emanuel Andrada, Patrick Arnold, Jonas Lauströer, John R. Hutchinson, Martin S. Fischer, and Auke J. Ijspeert, Reverse-engineering the locomotion of a stem amniote. Nature, 565 (7739):351-355, 2019/01/01 2019. https://doi.org/10.1038/s41586-018-0851-2