SVP abstracts – 7 on mesosaurs

Jannel et al 2022 continue,
“Yet, debates regarding its locomotory abilities are still ongoing and currently lack robust biomechanical testing. Here, we developed a novel combination of range of motion analysis and mathematical sinusoidal wave model to quantify the undulatory swimming capabilities of the mesosaur body axis, along with movements of their limbs.”

Some paleontologists are in the field getting dirty. Others are applying mathematical models. We need them them all.

Jannel et al 2022 continue,
“In parallel, we applied our model to the marine iguana Amblyrhynchus cristatus to validate our analysis on extant taxa and compare our results with one proposed living morphofunctional analogue of mesosaurs.

That usually entails a trip to the Galapagos and some diving equipment. Or did they handle this another way?

“We find that the vertebral column of M. tenuidens was remarkably flexible in each 3D-plane, particularly significant in the caudal region, allowing for a wide range of lateral undulatory swimming modes.

Most tetrapods are flexible laterally or dorsoventrally.
Only earthworms are flexible length-wise.

“This flexibility would have enabled mesosaurs to generate sufficient propulsive thrust to adopt a body-tail driven swimming locomotion. Based on similar swimming modes observed in our model analogue A. cristatus, we propose that mesosaurs likely used vertebral undulation as their main mode of locomotion when completely submerged.

Um. Yeahhh. That was kind of expected. Or am I the last to know?

“Additionally, our results show that both fore- and hindlimbs retained some degree of movements.

Ditto the above comment. Sorry to be snarky, but this is not breaking research.

We therefore suggest that this non-mutually exclusive aptitude allowed mesosaurs to simultaneously employ their limbs as secondary means of propulsion (an idea corroborated by their webbed autopodia) and/or balance mechanism, particularly at lower degrees of undulation.”

Was this abstract presentation well attended?

References
Jannel A et al (3 co-authors) 2022. A twist in the tail: reconstructing undulatory swimming in the first secondarily aquatic amniote. SVP abstracts 2022:198.