What is it about?

This study investigated whether studies of shoulder joint range of motion in dinosaurs are providing reliable estimates of living range of motion.

Featured Image

Why is it important?

The shoulder joint is the largest joint in the forelimb. This experiment provides a preliminary test of how soft tissues surrounding the joint (skin/scales/feathers, muscles/tendons and joint capsules/ligaments) and soft tissues within the joint (here articular cartilage) affect range of motion. A basic test such as this is needed as a starting point for further investigations of the effects of soft tissues on range of motion in dinosaurs and other fossil archosaurs. This experiment also builds upon a previous study of elbow joint range of motion in these same alligator and ostrich specimens (Hutson & Hutson, 2012), in order to begin comparing and contrasting the effects of soft tissues on range of motion in a diverse array of forelimb joints, with the goal of elucidating whether these results can be used to extrapolate living range of motion from fossil bones.

Perspectives

We expected the results of this experiment to provide data that showed that different observers are unlikely to measure similar ranges of motion at the same joint, as was expected for the elbow joint in these same animals (Hutson & Hutson, 2012). Surprisingly again, however, our statistical analysis of our repeated measures of joint range of motion indicated that most of our measurements were statistically insignificant. In other words, this means that we were both providing separate measurements close to an actual measurement and did not stray significantly far from it. Our interpretations of the effects of soft tissues on shoulder joint range of motion in living archosaurs (alligators & ostriches) were also comparable to those from our elbow joint range of motion experiment, meaning that soft tissues outside the joint seem to guide and restrict range of motion, while the cartilage inside the joint may guide and increase range of motion.

Joel David Hutson
DePaul University

Read the Original

This page is a summary of: Using the American alligator and a repeated-measures design to place constraints onin vivoshoulder joint range of motion in dinosaurs and other fossil archosaurs, Journal of Experimental Biology, September 2012, The Company of Biologists,
DOI: 10.1242/jeb.074229.
You can read the full text:

Read

Resources

Contributors

The following have contributed to this page