Lemur Headgear Helps Researchers Probe Prehistory

Lemurs in fancy hats are helping researchers better understand how extinct creatures moved. Although “fancy” may not be the best word for the attire (sadly, we’re not talking about fedoras or bowlers here). As part of a new PNAS study, researcher Michael Malinzak and colleagues fitted lemurs, lorises, and galagos of the Duke Lemur Center with special caps that tracked how the primates moved their heads as they walked, hopped, and clambered around.

The reason for the high-tech fashion was to gauge the relationship between head movements and the anatomy of the primates’ inner ears. From fossil humans to dinosaurs, researchers have often reconstructed the kind of head movements prehistoric animals were capable of by looking at the anatomy of semicircular canals within the ear. The size of the canals was thought to be an indicator of how fast the organisms could move their heads.

Yet the relationship between inner ear anatomy and head rotation has been marred by a lack of data about this phenomenon in living animals. Hence the headgear. By pairing data from head movements with measurements of inner ear sensitivity gathered from active animals, Malinzak and collaborators were able to take a more refined look at the relationship between form and function.

Contrary to what had previously been thought, the way the lemurs and lorises moved their heads was not constrained by the size of the inner ear canals. Instead, the orientation of the canals in relation to each other seemed to influence how quickly the study animals could rotate their heads. Inner ear anatomy is still important for movement, but in a way that was previously unexpected. Still, as Malinzak and colleagues point out, we need more information about head movement and inner ear anatomy from living animals to better gauge what extinct critters could do. That means more animals wearing high-tech hats.

Reference:

Malinzak, M., Kay, R., Hullar, T. (2012). Locomotor head movements and semicircular canal morphology in primates PNAS DOI: 10.1073/pnas.1206139109