Journal Article 1 Mention
March of the Titans: The Locomotor Capabilities of Sauropod Dinosaurs
William I. Sellers•2013
Lee MargettsRodolfo Aníbal Coria
Top 4% · 96th Percentile
94 citations · Paleontology
Open AccessStudies on the ecology of pathogenic Bartonella species in wildlife

TLDR

A giant dinosaur weighing about 83 tonnes could probably walk slowly, but only with stiff, limited leg movements. The simulation suggests that springy body tissues may have helped make walking more efficient.

Summary

1 Study Aim

The study aims to test how the giant sauropod Argentinosaurus huinculensis could have moved. The authors examine whether its size created mechanical limits on muscle force and joint movement. They use scaling theory (how physical demands change with body size) to predict possible constraints. The research also tests which joint movements and walking patterns could support the animal’s weight. The study asks whether this enormous dinosaur could walk using realistic muscles and bones.

2 Study Design

The authors laser-scanned a mounted Argentinosaurus skeleton and built a digital musculoskeletal model (a computer representation of bones, joints, and muscles). The reconstruction measured 39.7 metres and produced an estimated mass of 83,230 kilograms. They represented the body as linked rigid segments with simplified hinge joints and functional muscle groups. A forward dynamic simulation (a computer method that calculates movement from muscle forces) generated walking. A genetic algorithm (a search method inspired by evolution) adjusted 57 muscle-control parameters to increase forward movement while reducing metabolic energy use. Muscle properties came from comparative data on living animals. The researchers tested three different joint-movement conditions in repeated computer simulations.

3 Findings

The study reveals that the widest estimated joint movements could not produce a repeating walking gait because the model lacked enough muscle force. An elephant-based movement range allowed walking, but the wrist collapsed into a fully bent position. Restricting ankle movement produced a stable, plausible slow walk. The simulated gait resembled a diagonal-couplet walk, with footfall patterns similar to some sauropod trackways. Its most efficient cycle lasted about 2.8 seconds, but its energy cost was higher than expected from smaller animals. The authors argue that passive elastic structures (spring-like tissues that store and return energy) may have improved efficiency. They recommend adding these structures, spinal movement, feedback control, detailed muscles, and sensitivity testing in future models. The results suggest that this dinosaur could walk slowly, but its movement was near the limits imposed by its enormous size.

Abstract

Sauropod dinosaurs are the largest terrestrial vertebrate to have lived on Earth. This size must have posed special challenges for the musculoskeletal system. Scaling theory shows that body mass and hence the loads that must be overcome increases with body size more rapidly than either the ability of the muscles to generate force, or the ability of the skeleton to support these loads. Here we demonstrate how one of the very largest sauropods, Argentinosaurus huinculensis (40 metres long, weighing 83 tonnes), may have moved. A musculoskeletal model was generated using data captured by laser scanning a mounted skeleton and assigning muscle properties based on comparative data from living animals. Locomotion is generated using forward dynamic simulation to calculate the accelerations produced by the muscle forces, coupled with machine learning techniques to find a control pattern that minimises metabolic cost. The simulation demonstrates that at such vast body size, joint range of motion needs to be restricted to allow sufficient force generation for an achievable muscle mass. However when this is done, a perfectly plausible gait can be generated relatively easily. Whilst this model represents the best current simulation of the gait of these giant animals, it is likely that there are as yet unknown mechanical mechanisms, possibly based on passive elastic structures that should be incorporated to increase the efficiency of the animal's locomotion. It is certainly the case that these would need to be incorporated into the model to properly assess the full locomotor capabilities of the animal.

Referenced In