Paleontology

South American Sauropods Exhibited Greater Stability When Standing on Two Legs, Study Finds

A new ​study ​reveals that certain South American sauropods, specifically a juvenile Uberabatitan ribeiroi and Neuquensaurus australis, possessed femurs capable‍ of withstanding stress more ​effectively when standing on two legs compared to other sauropod species. The ⁢research, ⁣published in the ⁢journal Palaeontology,⁤ utilized digital reconstructions⁤ and finite element analysis (FEA) to simulate the biomechanics ‍of bipedal posture in seven sauropod species representing diverse evolutionary⁢ lineages.

The ​study was led by postdoctoral researcher Iago Silva Júnior from the School of Engineering of São Paulo State University (FEIS-UNESP) in Ilha Solteira, Brazil,​ and conducted during an internship at the University of Tübingen in Germany with a scholarship‌ from FAPESP. Silva Júnior, the first author of the study, and his team based their ‍digital models ⁣on fossils sourced from natural history museum collections globally.

FEA, a computational technique commonly used in engineering fields like bridge design, was employed to analyze both “extrinsic” forces – gravity and the animal’s weight – and “intrinsic” forces – muscle exertion – on the femur. The simulations indicated that​ the Uberabatitan ribeiroi (a juvenile) and Neuquensaurus australis, both​ living during⁢ the Late Cretaceous period approximately 66 million ⁢years ago, demonstrated the lowest levels of stress on their femurs.

“They had more robust femurs and‌ coudl dissipate ⁢stress ‍better,” Silva​ Júnior explained. While​ larger ⁢sauropods possessed ⁤substantial muscles and femurs, the ‌study suggests these were insufficient to ‌comfortably support⁣ their immense weight. The researchers acknowledge that while⁤ these larger dinosaurs could stand on their hind legs, it likely wasn’t a cozy or frequently chosen position.

The ability to stand⁢ on two legs would have offered several advantages for sauropods, ⁣including reaching higher vegetation for feeding, facilitating reproductive behaviors like mounting and displays, and potentially deterring predators by increasing apparent size.

The study’s authors note limitations, including the exclusion ⁣of cartilage – which ⁢contributes to stress dissipation -​ and the support provided by the tail ⁤in a ‌tripodal stance. They also assumed a consistent cartilage role across all specimens due to its absence in the fossils examined. However, Silva ‌Júnior emphasizes the value of the comparative approach. “The tool we use is very ​efficient for comparisons, even if the answer isn’t exact for each​ one. By comparing representatives ⁢from different lineages, we can get a fairly accurate picture of⁤ how these animals behaved millions of years ago.”

The full article, “Standing giants:⁤ a ‍digital biomechanical ⁤model for bipedal postures⁤ in sauropod dinosaurs,” is available at onlinelibrary.wiley.com/doi/10.1111/pala.70019.