Virtual Reconstruction and Prey Size Preference in the Mid Cenozoic Thylacinid, Nimbacinus dicksoni (Thylacinidae, Marsupialia)

Abstract

Thylacinidae is an extinct family of Australian and New Guinean marsupial carnivores, comprizing 12 known species, the oldest of which are late Oligocene (∼24 Ma) in age. Except for the recently extinct thylacine (Thylacinus cynocephalus), most are known from fragmentary craniodental material only, limiting the scope of biomechanical and ecological studies. However, a particularly well-preserved skull of the fossil species Nimbacinus dicksoni, has been recovered from middle Miocene (∼16-11.6 Ma) deposits in the Riversleigh World Heritage Area, northwestern Queensland. Here, we ask whether N. dicksoni was more similar to its recently extinct relative or to several large living marsupials in a key aspect of feeding ecology, i.e., was N. dicksoni a relatively small or large prey specialist. To address this question we have digitally reconstructed its skull and applied three-dimensional Finite Element Analysis to compare its mechanical performance with that of three extant marsupial carnivores and T. cynocephalus. Under loadings adjusted for differences in size that simulated forces generated by both jaw closing musculature and struggling prey, we found that stress distributions and magnitudes in the skull of N. dicksoni were more similar to those of the living spotted-tailed quoll (Dasyurus maculatus) than to its recently extinct relative. Considering the Finite Element Analysis results and dental morphology, we predict that N. dicksoni likely occupied a broadly similar ecological niche to that of D. maculatus, and was likely capable of hunting vertebrate prey that may have exceeded its own body mass.

Comparative finite element analysis of the cranial performance of four herbivorous marsupials

“…The difference between the wombat and kangaroo reflects their independent lines of evolution and multiple factors that drive selection of skull morphology. Many studies have used stress as a predictor of diet in extinct and extant animals, concluding that low stress indicates an adaptation for stronger skulls, given that lower stress means it is less likely to fail, and therefore, a diet high in hard foods is likely (Dumont et al, ; Tanner et al, ; Wroe, ; Attard et al, ; Young et al, ; Attard et al, ). It is assumed that selection for high structural strength is optimal and a driver for evolution within species that consume hard foods.…”

Feeding biomechanics of Late Triassic metoposaurids (Amphibia: Temnospondyli): a 3D finite element analysis approach

“…To compare the performances of structures that differ in shape and size, the values of muscular contraction pressure were calculated according to the methodology developed by Marc e-Nogu e et al (2013) and rearranged for 3D models by Fortuny et al (2015). This methodology relates the volume of each specimen with the applied muscular pressures by a 2/3 power relationship and agrees with the allometric proportions of the species (Meers, 2003;Wroe et al 2005;Attard et al 2014).…”

Accounting for differences in element size and homogeneity when comparing Finite Element models: Armadillos as a case study

“…In the last decade, researchers have used virtual reconstruction of vertebrate structures in order to perform biomechanical comparisons among taxa (Gunz et al, 2009;Doyle et al, 2009;Degrange et al, 2010;Fletcher et al, 2010;Attard et al, 2014;Figueirido et al, 2014;Neenan et al, 2014). According to O'Higgins and Milne (2013, p.1), "With further mathematical, engineering and statistical development the combination of computational methods as FEA, MDA and Morphometric Geometrics Methods (GMM) should open up new avenues of investigation of skeletal form and function in evolutionary biology" (MDA: Multibody Dynamics Analysis).…”