Moa diet fits the bill: virtual reconstruction incorporating mummified remains and prediction of biomechanical performance in avian giants

Abstract

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. 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.

Decoupling Functional and Morphological Convergence, the Study Case of Fossorial Mammalia

“…We applied on the models surface, over the selected restraint areas, an elastic solid mesh composed of beam elements (Structural Steel AS 4100-1998, Young's Modulus of 200,000 MPa). This strategy mitigates the impact of artifacts that can occur where single nodes are loaded (Attard et al, 2016;Tsang et al, 2019).…”

The intervals method: a new approach to analyse finite element outputs using multivariate statistics

“…The introduction of virtual models applied to biological structures represents an important advance for comparative biological studies achieved during the last few years (see review in Bright, 2014 ). In computational biomechanics, FEA has become increasingly popular among researchers due to its ability to show the biomechanical behaviour of anatomical structures, and is especially useful for analysing species where experimental approaches are not suitable ( Gunz et al, 2009 ; Pierce, Angielczyk & Rayfield, 2009 ; Degrange et al, 2010 ; Fletcher, Janis & Rayfield, 2010 ; Fortuny et al, 2011 ; Fortuny et al, 2015 ; Fortuny et al, 2016 ; Attard et al, 2016 ; Figueirido et al, 2014 ). FEA is a technique that acts by dividing a structure into a finite number (normally thousands or millions) of discrete elements with well-known mathematical properties (e.g., triangles, tetrahedrons or cubes).…”

120 Years of Untangling the Divaricate Habit: A Review

“…Greenwood & Atkinson (1977) did not completely exclude a cutting ability of moa beaks, 441 later acknowledging that the feeding behaviour of moa could not be confidently inferred because 442 fossil skulls do not retain all the relevant tissues (Atkinson & Greenwood 1989). A recent study 443 simulating the force of moa jaw muscles however concluded that different moa species fed in 444 various different ways, including cutting (Attard et al 2016). This appears to confirm the findings 445 of studies of moa gizzard contents, which concluded that that divaricate twigs consumed by moa 446 had been sheared rather than broken off (Burrows 1980(Burrows , 1989Burrows et al 1981).…”