Moa diet fits the bill

The moa (Dinornithiformes) are large to gigantic extinct terrestrial birds of New Zealand. Knowledge about niche partitioning, feeding mode and preference among moa species is limited, hampering palaeoecological reconstruction and evaluation of the impacts of their extinction on remnant native biota, or the viability of exotic species as proposed ecological ‘surrogates’.

Here we apply three-dimensional finite-element analysis to compare the biomechanical performance of skulls from five of the six moa genera, and two extant ratites, to predict the range of moa feeding behaviours relative to each other and to living relatives.

Jaw muscles obtained from MRI scan used to create finite models of moa skulls. Credit: Marie Attard

We digitally extracted the main jaw closing muscles from an MRI scan of a mummified moa. These were used as a guide to determine where jaw muscles attached on moa skulls.

Stress distribution on the skull of moa species and extant ratites. Source: Attard et al. (2016) Proceedings of Royal Society B

Mechanical performance during biting was compared using simulations of the birds clipping twigs based on muscle reconstruction of mummified moa remains. Other simulated food acquisition strategies included lateral shaking, pullback and dorsoventral movement of the skull.

We found evidence for limited overlap in biomechanical performance between the extant emu (Dromaius novaehollandiae) and extinct upland moa (Megalapteryx didinus) based on similarities in mandibular stress distribution in two loading cases, but overall our findings suggest that moa species exploited their habitats in different ways, relative to both each other and extant ratites.

The broad range of feeding strategies used by moa, as inferred from interspecific differences in biomechanical performance of the skull, provides insight into mechanisms that facilitated high diversities of these avian herbivores in prehistoric New Zealand.

Published

Attard, MRG, Wilson LAB, Worthy TH, Scofield P, Johnston P, Parr WCH and Wroe S (2016) Moa diet fits the bill: virtual reconstruction incorporating mummified remains and prediction of biomechanical performance in avian giants. Proceedings of Royal Society B. 283(1822). DOI: 10.1098/rspb.2015.2043.