Biomechanical Analysis Reveals Young Sauropods Could Stand Upright as "Geniuses of Balance" Before Maturity

Computational simulations show smaller sauropods like Uberabatitan could stand on hind legs in youth, but growth made the posture stressful in adulthood.

By: AXL Media

Published: Mar 30, 2026, 11:14 AM EDT

Source: Information for this report was sourced from Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The Evolutionary Advantage of the Upright Stance

Approximately 66 million years ago, the landscape of the Late Cretaceous was dominated by long-necked sauropods that developed a surprising behavioral flexibility. While traditionally viewed as strictly quadrupedal, certain species like the Brazilian Uberabatitan and the Argentine Neuquensaurus utilized a bipedal stance to navigate their environment. This posture provided a significant survival edge, allowing these herbivores to access high-canopy vegetation that remained out of reach for their competitors. Beyond feeding, the ability to rise up likely served as a defensive display to intimidate predators and may have played a critical role in mating rituals and visual communication within the herd.

Engineering Physics Applied to Prehistoric Bone Stress

To determine the physical feasibility of this behavior, a multinational research team employed Finite Element Analysis (FEA)—the same computational method used by engineers to test the structural integrity of bridges and aircraft. By creating digital reconstructions of femurs from seven different sauropod species, the scientists simulated both "extrinsic" forces, such as gravity and body weight, and "intrinsic" forces exerted by the animal's massive leg muscles. The goal was to quantify the exact level of stress placed on the femur during bipedal standing to see which species could biologically afford the maneuver.

The Resilience of South American Lineages

The simulations revealed that the juvenile Uberabatitan ribeiroi and the Neuquensaurus australis exhibited the lowest levels of femoral stress among the specimens studied. These species featured more robust bone structures that were exceptionally efficient at dissipating the mechanical pressure of their weight. Julian Silva Júnior, the study’s lead author from FEIS-UNESP, noted that these smaller sauropods—roughly the size of modern elephants—possessed a skeletal architecture that allowed them to remain upright for extended periods with relative ease compared to their more gargantuan relatives.