When gazing at a pile of bones displayed in a museum, it takes some effort to imagine this creature roaming about the Earth, full of life. With the help of scientists at EPFL and Humboldt University of Berlin, we can easily travel back hundreds of millions of years by fusing fossils with robotics.
Finding the Right Ancient Candidate
Researchers used the fossil and fossilized footprints of a 300-million-year-old animal known as Orobates pabsti, to study different plausible ways this creature strutted about. Orobates resides on a critical branch of the evolutionary tree, connecting early amphibians with reptiles and mammals.
“Orobates is an ideal candidate for understanding how land vertebrates evolved because it is in the lineage leading to modern amniotes. These animals formed in eggs laid on land and became largely independent of water,” says Humboldt University Professor John Nyakatura.
The animal has another favorable feature—it’s the oldest-known vertebrate where scientists were able to link its fossil with its fossilized footprints.
Bringing the Past to Life with Robotics
To figure out the Orobates’ locomotion, the Humboldt University team first re-created its skeleton as a digital model, based on the actual fossil and modern-day animals with a similar posture. The simulations helped with gait analysis and focused on movement as opposed to forces, studying how to bones and joints naturally shift.
At the same time, EPFL researchers got to work on the actual Orobates robot, called OroBOT. Designed to scale, OroBOT was built to calculate the physics of the walk.
“We tested our hypotheses about the animal’s locomotion dynamics with our robotic model, which factors in the real-world physics of the animal’s gait,” says Kamilo Melo, EPFL post-doctoral researcher.
Testing Gaits by the Hundreds
Hundreds of different gaits were tested with OroBOT, according to EPFL. While drawing on the biomechanics of its contemporary counterparts, three distinct features rose to focus: the bend of the backbone, the bend of the elbow or shoulder joint while walking, and how erect it stood on its legs.
Researchers settled on a more athletic gait akin to caimans, suggesting it held itself slightly upright on its legs, unlike today’s salamanders.
“The study concludes that advanced—more upright, balanced, and mechanically power-saving—locomotion, as in Orobates, may have evolved before the common ancestor of reptiles and mammals lived. The novel approach developed for this study can be applied by other scientists in their work, and it could be modified to study other evolutionary transitions, such as the origins of flight or galloping gaits in mammals,” according to EPFL.
The team created an interactive website demonstrating a walking Orobates pabsti, and outlined their findings in the study, “Reverse-engineering the locomotion of a stem amniote,” published in Nature.