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Stephen Wroe

University of New England - Australia, Zoology, Faculty Member

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Research interests:
Form-function relationships, feeding ecology and systematics in living and fossil taxa; including humans and other primates, marsupial and placental carnivores, sharks, crocodiles, terror birds and varanids.
The use of Finite Element Analysis in biology to examine cranial mechanics and predict feeding behaviour.
The application of FEA to biomedical questions.
Extinction of the Australian megafauna.
Marsupial carnivore phylogeny and biogeography.
Vertebrate palaeontology/paleontology.
Bite forces.
Phone: 61 2 67733261

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SISSA

Los Alamos National Laboratory

Alexander Poteryaev

University of California, San Diego

gabriel kotliar

Rutgers, The State University of New Jersey

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Papers by Stephen Wroe

Dynamical breakup of the Fermi surface in a doped mott insulator

The evolution from an anomalous metallic phase to a Mott insulator within the two-dimensional Hub... more The evolution from an anomalous metallic phase to a Mott insulator within the two-dimensional Hubbard model is investigated by means of the Cellular Dynamical Mean-Field Theory. We show that the density-driven Mott metal-insulator transition is approached in a non-uniform way in different regions of the momentum space. This gives rise to a breakup of the Fermi surface and to the formation of hot and cold regions, whose position depends on the hole or electron like nature of the carriers in the system.

Morphological integration affects the evolution of midline cranial base, lateral basicranium, and face across primates

by Sarah Ledogar and Stephen Wroe

American Journal of Physical Anthropology, 2019

The basicranium and face are two integrated bony structures displaying great morphological divers... more The basicranium and face are two integrated bony structures displaying great morphological diversity across primates. Previous studies in hominids determined that the basicranium is composed of two independent modules: the midline basicranium, mostly influenced by brain size, and the lateral basicranium, predominantly associated with facial shape. To better assess how morphological integration impacts the evolution of primate cranial shape diversity, we test to determine whether the relationships found in hominids are retained across the order. Materials and methods: Three-dimensional landmarks (29) were placed on 143 computed tomography scans of six major clades of extant primate crania. We assessed the covariation between midline basicranium, lateral basicranium, face, and endocranial volume using phylogenetically informed partial least squares analyses and phylogenetic generalized least squares models. Results: We found significant integration between lateral basicranium and face and between midline basicranium and face. We also described a significant correlation between midline basicranium and endocranial volume but not between lateral basicranium and endocranial volume. Discussion: Our findings demonstrate a significant and pervasive integration in the craniofacial structures across primates, differing from previous results in hominids. The uniqueness of module organization in hominids may explain this distinction. We found that endocranial volume is significantly integrated to the midline basicranium but not to the lateral basicranium. This finding underlines the significant effect of brain size on the shape of the midline structures of the cranial base in primates. With the covariations linking the studied features defined here, we suggest that future studies should focus on determining the causal links between them.

Bicknell, R.D.C., Klinkhamer, A.J., Flavel, R.J., Wroe, S. & Paterson, J.R., 2018. A 3D anatomical atlas of appendage musculature in the chelicerate arthropod Limulus polyphemus. PLoS ONE, 13(2), e0191400.

by John Paterson and Stephen Wroe

Limulus polyphemus, an archetypal chelicerate taxon, has interested both biological and paleontol... more Limulus polyphemus, an archetypal chelicerate taxon, has interested both biological and paleontological researchers due to its unique suite of anatomical features and as a useful modern analogue for fossil arthropod groups. To assist the study and documentation of this iconic taxon, we present a 3D atlas on the appendage musculature, with specific focus on the muscles of the cephalothoracic appendages. As L. polyphemus appendage muscula-ture has been the focus of extensive study, depicting the muscles in 3D will facilitate a more complete understanding thereof for future researchers. A large museum specimen was CT scanned to illustrate the major exoskeletal features of L. polyphemus. Micro-CT scans of iodine-stained appendages from fresh, non-museum specimens were digitally dissected to interactively depict appendage sections and muscles. This study has revealed the presence of two new muscles: one within the pushing leg, located dorsally relative to all other patella muscles, and the other within the male pedipalp, located in the modified tibiotarsus. This atlas increases accessibility to important internal and external morphological features of L. polyphemus and reduces the need for destructive fresh tissue dissection of specimens. Scanning, digitally dissecting, and documenting taxa in 3D is a pivotal step towards creating permanent digital records of life on Earth.

Computer simulations show that Neanderthal facial morphology represents adaptation to cold and high energy demands, but not heavy biting

by Stephen Wroe and Luca Fiorenza

Three adaptive hypotheses have been forwarded to explain the distinctive Neanderthal face: (i) an... more Three adaptive hypotheses have been forwarded to explain the distinctive Neanderthal face: (i) an improved ability to accommodate high anterior bite forces, (ii) more effective conditioning of cold and/or dry air and, (iii) adaptation to facilitate greater ventilatory demands. We test these hypotheses using three-dimensional models of Neanderthals, modern humans, and a close outgroup (Homo heidelbergensis), applying finite-element analysis (FEA) and computational fluid dynamics (CFD). This is the most comprehensive application of either approach applied to date and the first to include both. FEA reveals few differences between H. heidel-bergensis, modern humans, and Neanderthals in their capacities to sustain high anterior tooth loadings. CFD shows that the nasal cavities of Nean-derthals and especially modern humans condition air more efficiently than does that of H. heidelbergensis, suggesting that both evolved to better withstand cold and/or dry climates than less derived Homo. We further find that Neanderthals could move considerably more air through the nasal pathway than could H. heidelbergensis or modern humans, consistent with the propositions that, relative to our outgroup Homo, Neanderthal facial morphology evolved to reflect improved capacities to better condition cold, dry air, and, to move greater air volumes in response to higher energetic requirements.

On the rarity of big fierce carnivores and primacy of isolation and area: tracking large mammalian carnivore diversity on two isolated continents

by Christine Argot, Christopher Dickman, and Stephen Wroe

Proceedings of the Royal Society B: Biological Sciences, 2004

The hypothesis that low productivity has uniquely constrained Australia's large mammalian carnivo... more The hypothesis that low productivity has uniquely constrained Australia's large mammalian carnivore diversity, and by inference the biota in general, has become an influential backdrop to interpretations of ecology on the island continent. Whether low productivity has been primary impacts broadly on our understanding of mammalian biogeography, but investigation is complicated by two uniquely Australian features: isolation and the dominance of marsupials. However, until the great American biotic interchange (GABI), South America was also isolated and dominated by pouched carnivores. Here, we examine the low-productivity hypothesis empirically, by comparing large mammalian carnivore diversities in Australia and South America over the past 25 Myr. We find that pre-GABI diversity in Australia was generally comparable to or higher than diversity in South America. Post-GABI, South American diversity rose dramatically, pointing to isolation and phylogenetic constraint as primary influences. Landmass area is another important factor. Comparisons of diversity among the world's seven largest inhabited landmasses show that large mammalian hypercarnivore diversity in Australia approached levels predicted on the basis of landmass area in Late Pleistocene-Recent times, but large omnivore diversity was low. Large marsupial omnivores also appear to have been rare in South America. Isolation and competition with large terrestrial birds and cryptic omnivore taxa may have been more significant constraints in this respect. Relatively high diversity has been achieved in Late Quaternary America, possibly as a result of 'artificially' high immigration or origination rates, whereas that in contemporaneous Africa has been surprisingly poor. We conclude that isolation and landmass area, rather than productivity, are the primary constraints on large mammalian carnivore diversity. Our results quantify the rarity of large hypercarnivorous mammals worldwide.

High-Resolution Three-Dimensional Computer Simulation of Hominid Cranial Mechanics

by Darren Curnoe, Stephen Wroe, and Philip Clausen

In vivo data demonstrates that strain is not distributed uniformly on the surface of the primate ... more In vivo data demonstrates that strain is not distributed uniformly on the surface of the primate skull during feeding. However, in vivo studies are unable to identify or track changes in stress and strain throughout the whole structure. Finite element (FE) analysis, a powerful engineering tool long used to predict the performance of man-made devices, has the capacity to track stress/strain in three dimensions (3-D) and, despite the time-consuming nature of model generation, FE has become an increasingly popular analytical device among biomechanists. Here, we apply the finite element method using sophisticated computer models to examine whether 3-D stress and strain distributions are nonuniform throughout the primate skull, as has been strongly suggested by 2-D in vivo strain analyses. Our simulations document steep internal stress/strain gradients , using models comprising up to three million tetrahedral finite elements and 3-D reconstructions of jaw adducting musculature with both cranium and mandible in correct anatomical position. Results are in broad concurrence with the suggestion that few regions of the hominid cranium are clearly optimized for routine feeding and also show that external stress/strain does not necessarily reflect internal distributions. Findings further suggest that the complex heterogeneity of bone in the skull may act to dissipate stress, but that consequently higher strain must be offset by additional strain energy. We hypothesize that, despite energetic costs, this system may lend adaptive advantage through enhancing the organism's ability to modify its behavior before reaching catastrophic failure in bony or dental structures.

The craniomandibular mechanics of being human "Data Supplement" Subject collections Email alerting service

by Darren Curnoe and Stephen Wroe

Citations to Advance online articles must include the digital object identifier (DOIs) and date o... more Citations to Advance online articles must include the digital object identifier (DOIs) and date of initial online articles are citable and establish publication priority; they are indexed by PubMed from initial publication. the paper journal (edited, typeset versions may be posted when available prior to final publication). Advance Advance online articles have been peer reviewed and accepted for publication but have not yet appeared in http://rspb.royalsocietypublishing.org/subscriptions

Human Remains from the Pleistocene-Holocene Transition of Southwest China Suggest a Complex Evolutionary History for East Asians

by Darren Curnoe, Paul Tacon, and Stephen Wroe

Background: Later Pleistocene human evolution in East Asia remains poorly understood owing to a s... more Background: Later Pleistocene human evolution in East Asia remains poorly understood owing to a scarcity of well described, reliably classified and accurately dated fossils. Southwest China has been identified from genetic research as a hotspot of human diversity, containing ancient mtDNA and Y-DNA lineages, and has yielded a number of human remains thought to derive from Pleistocene deposits. We have prepared, reconstructed, described and dated a new partial skull from a consolidated sediment block collected in 1979 from the site of Longlin Cave (Guangxi Province). We also undertook new excavations at Maludong (Yunnan Province) to clarify the stratigraphy and dating of a large sample of mostly undescribed human remains from the site.

Resolving the evolution of the mammalian middle ear using Bayesian inference

by Hector E. Ramírez-Chaves and Stephen Wroe

Background: The minute, finely-tuned ear ossicles of mammals arose through a spectacular evolutio... more Background: The minute, finely-tuned ear ossicles of mammals arose through a spectacular evolutionary transformation from their origins as a load-bearing jaw joint. This involved detachment from the postdentary trough of the mandible, and final separation from the dentary through resorption of Meckel's cartilage. Recent parsimony analyses of modern and fossil mammals imply up to seven independent postdentary trough losses or even reversals, which is unexpected given the complexity of these transformations. Here we employ the first model-based, probabilistic analysis of the evolution of the definitive mammalian middle ear, supported by virtual 3D erosion simulations to assess for potential fossil preservation artifacts. Results: Our results support a simple, biologically plausible scenario without reversals. The middle ear bones detach from the postdentary trough only twice among mammals, once each in the ancestors of therians and monotremes. Disappearance of Meckel's cartilage occurred independently in numerous lineages from the Late Jurassic to the Late Cretaceous. This final separation is recapitulated during early development of extant mammals, while the earlier-occurring disappearance of a postdentary trough is not. Conclusions: Our results therefore suggest a developmentally congruent and directional two-step scenario, in which the parallel uncoupling of the auditory and feeding systems in northern and southern hemisphere mammals underpinned further specialization in both lineages. Until ~168 Ma, all known mammals retained attached middle ear bones, yet all groups that diversified from ~163 Ma onwards had lost the postdentary trough, emphasizing the adaptive significance of this transformation.

Cranial shape variation and phylogenetic relationships of extinct and extant Old World leaf-nosed bats

by Camilo López Aguirre, Karen Black, and Stephen Wroe

The leaf-nosed bats in Hipposideridae and Rhinonycteridae currently have an Old World tropical to... more The leaf-nosed bats in Hipposideridae and Rhinonycteridae currently have an Old World tropical to subtropical distribution, with a fossil record extending back to the middle Eocene of Europe. The Riversleigh World Heritage fossil site in northwestern Queensland constitutes a particularly rich archive of faunal diversity for Old World leaf-nosed bats, having yielded more than 20 species. We used 2D geometric morphometrics to quantify cranial shape in hipposiderids and rhinonycterids, with the aim of referring unallocated fossil species, particularly from Riversleigh, to each family within a phylogenetic framework, and using a quantitative approach to reconstruct cranial shape for key clades in these Old World radiations. Our sample comprised 21 extant hipposiderids and rhinonycterids, 1 megadermatid and 1 rhinolophid, in which 31 landmarks were placed in lateral and ventral views, and five measurements were taken in dorsal view. The phylogeny used as the framework for this study was based on an analysis of 64 discrete morphological characters from the dentition, cranium and postcranium scored for 42 extant and fossil hipposiderids and rhinonycterids and five outgroup taxa (rhinolophids and megadermatids). The phylogenetic analysis was conducted using maximum parsimony, with relationships among selected extant taxa constrained to match the results of recent comprehensive molecular studies. Our phylogenetic results suggest that the Riversleigh leaf-nosed bats probably do not represent an endemic Australian radiation, with fossil species spread throughout the tree and several with sister-group relationships with non-Australian taxa. Discriminant analyses (DA) conducted separately on each dataset resulted in cross-validated classification success ranging from 61.9% for ventral landmarks to 71.4% for lateral landmarks. Classification of the original grouped cases resulted in success of 81% for each dataset. Of the eight fossil taxa included as unknowns in the DA, six were found to be assigned to the same group as recovered by the phylogenetic analysis. From our results, we assign the Riversleigh Miocene species Archerops annectens, Brachipposideros watsoni, Brevipalatus mcculloughi, Rhinonicteris tedfordi and Xenorhinos halli to Rhinonycteridae, and Riversleigha williamsi and Hipposideros bernardsigei to Hipposideridae. Our results support Pseudorhinolophus bouziguensis, from the early Miocene of Bouzigues in southern France, as belonging to Hipposideridae, and probably Hipposideros. The reconstructed ancestor of hipposiderids was distinguished from that of the rhinonycterids by having a shorter rostrum, and less of a distinction between the rostrum and braincase.

Mammalian development does not recapitulate suspected key transformations in the evolutionary detachment of the mammalian middle ear

The ectotympanic, malleus and incus of the developing mammalian middle ear (ME) are initially att... more The ectotympanic, malleus and incus of the developing mammalian middle ear (ME) are initially attached to the dentary via Meckel's cartilage, betraying their origins from the primary jaw joint of land vertebrates. This recapitulation has prompted mostly unquantified suggestions that several suspected—but similarly unquantified—key evolutionary transformations leading to the mammalian ME are recapitulated in development, through negative allometry and posterior/medial displacement of ME bones relative to the jaw joint. Here we show, using mCT reconstructions, that neither allometric nor topological change is quantifiable in the pre-detachment ME development of six marsu-pials and two monotremes. Also, differential ME positioning in the two monotreme species is not recapitulated. This challenges the developmental prerequisites of widely cited evolutionary scenarios of definitive mammalian middle ear (DMME) evolution, highlighting the requirement for further fossil evidence to test these hypotheses. Possible association between rear molar eruption, full ME ossification and ME detachment in marsupials suggests functional divergence between dentary and ME as a trigger for developmental , and possibly also evolutionary, ME detachment. The stable positioning of the dentary and ME supports suggestions that a 'partial mammalian middle ear' as found in many mammaliaforms—probably with a cartilaginous Meckel's cartilage—represents the only developmentally plausible evolutionary DMME precursor.

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

by Stephen Wroe and Paul Scofield

The moa (Dinornithiformes) are large to gigantic extinct terrestrial birds of New Zealand. Knowle... more 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 bio-mechanical 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 biomecha-nical performance between the extant emu (Dromaius novaehollandiae) and extinct upland moa (Megalapteryx didinus) based on similarities in mandibu-lar 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.

To Meat or Not to Meat? New Perspectives on Neanderthal Ecology

by Stefano Benazzi, Andrea Picin, and Stephen Wroe

Neanderthals have been commonly depicted as top predators who met their nutritional needs by focu... more Neanderthals have been commonly depicted as top predators who met their nutritional needs by focusing entirely on meat. This information mostly derives from faunal assemblage analyses and stable isotope studies: methods that tend to underestimate plant consumption and overestimate the intake of animal proteins. Several studies in fact demonstrate that there is a physiological limit to the amount of animal proteins that can be consumed: exceeding these values causes protein toxicity that can be particularly dangerous to pregnant women and newborns. Consequently, to avoid food poisoning from meat-based diets, Neander-thals must have incorporated alternative food sources in their daily diets, including plant materials as well. Yrbk Phys Anthropol 156:43–71, 2015. V C 2014 American Association of Physical Anthropologists In this manuscript, we review traditional as well as more recent approaches for reconstructing the diet in past human populations, and we show how new archaeological discoveries and innovative methods are changing our views of Neanderthal ecology and behavior. We further underline the importance of reconstructing Nean-derthal environments derived from palaeoecological data to better understand and interpret the dietary evidence obtained by these methods. Finally, since the intake of specific foods can be invisible to certain techniques and detect by others, we suggest using a more holistic approach by integrating the findings of more than one method. Such comprehensive analyses would enable the reconstruction of the whole dietary spectrum, which is particularly important for species like Neanderthal, who lived under severe and unstable climatic conditions. Neanderthals are undoubtedly the most studied and best-known group in the human fossil record. Despite that, for more than 100 years since their discovery, research on Neanderthal ecology, subsistence strategies, and diet have received remarkably little attention (Ready, 2010). It is only with the emergence of new archeological disciplines and development of innovative analytical approaches in the 1960s, that scholars began to look at Neanderthal behavior and adaptations to their environment. Methods such as faunal analysis, lithic technology, and taphonomic studies progressively led to a general portrait that defined Neanderthals as a homogenous group, with similar nutritional needs typified by a reliance on the consumption of terrestrial animals. This idea was reinforced by the study of stable isotopes and Neanderthal anatomy. The general robusticity of Nean-derthal skeletons, with relatively short limbs and heavy trunks, has been interpreted as adaptation to cold stress environments that follow the ecogeographic principles of Bergmann's and Allen's rules (e.

Cranial Shape and the Modularity of Hybridization in Dingoes and Dogs; Hybridization Does Not Spell the End for Native Morphology

by Stephen Wroe and Mathew S Crowther

Australia's native wild dog, the dingo (Canis dingo), is threatened by hybridization with feral o... more Australia's native wild dog, the dingo (Canis dingo), is threatened by hybridization with feral or domestic dogs. In this study we provide the first comprehensive three dimensional geometric morphometric evaluation of cranial shape for dingoes, dogs and their hybrids. We introduce a novel framework to assess whether mod-ularity facilitates, or constrains, cranial shape change in hybridization. Our results show that hybrid and pure dingo morphology overlaps greatly, meaning that hybrids cannot be reliably distinguished from dingoes on the basis of cranial metrics. We find that dingo morphology is resistant, with observed hybrids exhibiting morphology closer to the dingo than to the parent group dog. We also find that that hybridization with dog breeds does not push the dingo cranial morphology towards the wolf phenotype. Disparity and integration analyses on the ten recovered modules provided empirical support for modularity facilitating shape change over short evolutionary time scales. However , our results show that this is may not be the case in hybridization events, which were not influenced by module integration or disparity levels. We conclude that although hybridization events may introduce breed dog DNA to the dingo population, the native cranial morphology, and therefore likely the feeding eco-niche, of the dingo population is resistant to change. Our results have implications for conservation and management of dingoes and, more broadly, for the influence of integration patterns over ecological time scales in relation to selection pressure.

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

by Stephen Wroe and Tracey Rogers

Thylacinidae is an extinct family of Australian and New Guinean marsupial carnivores, comprizing ... more 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.

Chronological overlap between humans and megafauna in Sahul (Pleistocene Australia–New Guinea): A review of the evidence

by Melanie Fillios and Stephen Wroe

Earth-Science Reviews, 2008

Over 60 faunal species disappeared from the Australian continent during the Middle-Late Pleistoce... more Over 60 faunal species disappeared from the Australian continent during the Middle-Late Pleistocene. Most of these animals were large to gigantic marsupials, birds and reptiles. A terminal extinction date of 46.4 kyr has been proposed for the megafauna, with all sites containing younger fossil megafauna dismissed by some researchers because of questions over stratigraphic integrity or chronologies. The timing of the extinctions is argued to be broadly coincident with estimates of first colonization of the continent by modern humans, and explanatory extinction models involving humans have subsequently gained currency. However there is considerable evidence to suggest that in some parts of the continent, people and some species of megafauna may have co-existed well beyond 46.4 kyr. In other places, such as Tasmania and the north of the continent, there is no known record of a human-megafauna temporal overlap. A review of the available evidence indicates that only 13 species of megafauna were extant on human arrival in Australia. The archaeology of this period indicates that rather than a focus on big game hunting or 'firestick farming', it was characterized by regional variability in subsistence strategies consistent with the range of environmental zones. At the present time there is no substantive argument for a terminal extinction date of 46.4 kyr, the current evidence indicating that there is no specific time period that correlates to any single mass extinction event. On the basis of available evidence arguments for either human or climatic causation are entirely circumstantial and implicitly require acceptance of many unproven assumptions. Claims to have eliminated climate as a primary driver are premature and the recent focus on delivering 'proof' of human causation in Pleistocene faunal extinctions diverts attention from achieving a better understanding of the differential impacts of climate change and short term climatic flux in a land of environmental extremes.

CONFIRMATION OF THYLACINUS FROM THE PLIOCENE CHINCHILLA LOCAL FAUNA

Large orb-webs adapted to maximise total biomass not rare, large prey

Scientific reports, 2015

Spider orb-webs are the ultimate anti-ballistic devices, capable of dissipating the relatively ma... more Spider orb-webs are the ultimate anti-ballistic devices, capable of dissipating the relatively massive kinetic energy of flying prey. Increased web size and prey stopping capacity have co-evolved in a number orb-web taxa, but the selective forces driving web size and performance increases are under debate. The rare, large prey hypothesis maintains that the energetic benefits of rare, very large prey are so much greater than the gains from smaller, more common prey that smaller prey are irrelevant for reproduction. Here, we integrate biophysical and ecological data and models to test a major prediction of the rare, large prey hypothesis, that selection should favour webs with increased stopping capacity and that large prey should comprise a significant proportion of prey stopped by a web. We find that larger webs indeed have a greater capacity to stop large prey. However, based on prey ecology, we also find that these large prey make up a tiny fraction of the total biomass (=energy) ...

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

Proceedings. Biological sciences / The Royal Society, Jan 13, 2016

The moa (Dinornithiformes) are large to gigantic extinct terrestrial birds of New Zealand. Knowle... more 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 extan...

Ferrara et al 2011 - GWS vs GNS bite - J Biomechanics44

by Toni Ferrara, Victor Peddemors, Stephen Wroe, and Philip Clausen

Although a strong correlation between jaw mechanics and prey selection has been demonstrated in b... more Although a strong correlation between jaw mechanics and prey selection has been demonstrated in bony fishes (Osteichthyes), how jaw mechanics influence feeding performance in cartilaginous fishes (Chondrichthyes) remains unknown. Hence, tooth shape has been regarded as a primary predictor of feeding behavior in sharks. Here we apply Finite Element Analysis (FEA) to examine form and function in the jaws of two threatened shark species, the great white (Carcharodon carcharias) and the sandtiger (Carcharias taurus). These species possess characteristic tooth shapes believed to reflect dietary preferences. We show that the jaws of sandtigers and great whites are adapted for rapid closure and generation of maximum bite force, respectively, and that these functional differences are consistent with diet and dentition. Our results suggest that in both taxa, insertion of jaw adductor muscles on a central tendon functions to straighten and sustain muscle fibers to nearly orthogonal insertion angles as the mouth opens. We argue that this jaw muscle arrangement allows high bite forces to be maintained across a wider range of gape angles than observed in mammalian models. Finally, our data suggest that the jaws of sub-adult great whites are mechanically vulnerable when handling large prey. In addition to ontogenetic changes in dentition, further mineralization of the jaws may be required to effectively feed on marine mammals. Our study is the first comparative FEA of the jaws for any fish species. Results highlight the potential of FEA for testing previously intractable questions regarding feeding mechanisms in sharks and other vertebrates.

Dynamical breakup of the Fermi surface in a doped mott insulator

The evolution from an anomalous metallic phase to a Mott insulator within the two-dimensional Hub... more The evolution from an anomalous metallic phase to a Mott insulator within the two-dimensional Hubbard model is investigated by means of the Cellular Dynamical Mean-Field Theory. We show that the density-driven Mott metal-insulator transition is approached in a non-uniform way in different regions of the momentum space. This gives rise to a breakup of the Fermi surface and to the formation of hot and cold regions, whose position depends on the hole or electron like nature of the carriers in the system.

Morphological integration affects the evolution of midline cranial base, lateral basicranium, and face across primates

by Sarah Ledogar and Stephen Wroe

American Journal of Physical Anthropology, 2019

The basicranium and face are two integrated bony structures displaying great morphological divers... more The basicranium and face are two integrated bony structures displaying great morphological diversity across primates. Previous studies in hominids determined that the basicranium is composed of two independent modules: the midline basicranium, mostly influenced by brain size, and the lateral basicranium, predominantly associated with facial shape. To better assess how morphological integration impacts the evolution of primate cranial shape diversity, we test to determine whether the relationships found in hominids are retained across the order. Materials and methods: Three-dimensional landmarks (29) were placed on 143 computed tomography scans of six major clades of extant primate crania. We assessed the covariation between midline basicranium, lateral basicranium, face, and endocranial volume using phylogenetically informed partial least squares analyses and phylogenetic generalized least squares models. Results: We found significant integration between lateral basicranium and face and between midline basicranium and face. We also described a significant correlation between midline basicranium and endocranial volume but not between lateral basicranium and endocranial volume. Discussion: Our findings demonstrate a significant and pervasive integration in the craniofacial structures across primates, differing from previous results in hominids. The uniqueness of module organization in hominids may explain this distinction. We found that endocranial volume is significantly integrated to the midline basicranium but not to the lateral basicranium. This finding underlines the significant effect of brain size on the shape of the midline structures of the cranial base in primates. With the covariations linking the studied features defined here, we suggest that future studies should focus on determining the causal links between them.

Bicknell, R.D.C., Klinkhamer, A.J., Flavel, R.J., Wroe, S. & Paterson, J.R., 2018. A 3D anatomical atlas of appendage musculature in the chelicerate arthropod Limulus polyphemus. PLoS ONE, 13(2), e0191400.

by John Paterson and Stephen Wroe

Limulus polyphemus, an archetypal chelicerate taxon, has interested both biological and paleontol... more Limulus polyphemus, an archetypal chelicerate taxon, has interested both biological and paleontological researchers due to its unique suite of anatomical features and as a useful modern analogue for fossil arthropod groups. To assist the study and documentation of this iconic taxon, we present a 3D atlas on the appendage musculature, with specific focus on the muscles of the cephalothoracic appendages. As L. polyphemus appendage muscula-ture has been the focus of extensive study, depicting the muscles in 3D will facilitate a more complete understanding thereof for future researchers. A large museum specimen was CT scanned to illustrate the major exoskeletal features of L. polyphemus. Micro-CT scans of iodine-stained appendages from fresh, non-museum specimens were digitally dissected to interactively depict appendage sections and muscles. This study has revealed the presence of two new muscles: one within the pushing leg, located dorsally relative to all other patella muscles, and the other within the male pedipalp, located in the modified tibiotarsus. This atlas increases accessibility to important internal and external morphological features of L. polyphemus and reduces the need for destructive fresh tissue dissection of specimens. Scanning, digitally dissecting, and documenting taxa in 3D is a pivotal step towards creating permanent digital records of life on Earth.

Computer simulations show that Neanderthal facial morphology represents adaptation to cold and high energy demands, but not heavy biting

by Stephen Wroe and Luca Fiorenza

Three adaptive hypotheses have been forwarded to explain the distinctive Neanderthal face: (i) an... more Three adaptive hypotheses have been forwarded to explain the distinctive Neanderthal face: (i) an improved ability to accommodate high anterior bite forces, (ii) more effective conditioning of cold and/or dry air and, (iii) adaptation to facilitate greater ventilatory demands. We test these hypotheses using three-dimensional models of Neanderthals, modern humans, and a close outgroup (Homo heidelbergensis), applying finite-element analysis (FEA) and computational fluid dynamics (CFD). This is the most comprehensive application of either approach applied to date and the first to include both. FEA reveals few differences between H. heidel-bergensis, modern humans, and Neanderthals in their capacities to sustain high anterior tooth loadings. CFD shows that the nasal cavities of Nean-derthals and especially modern humans condition air more efficiently than does that of H. heidelbergensis, suggesting that both evolved to better withstand cold and/or dry climates than less derived Homo. We further find that Neanderthals could move considerably more air through the nasal pathway than could H. heidelbergensis or modern humans, consistent with the propositions that, relative to our outgroup Homo, Neanderthal facial morphology evolved to reflect improved capacities to better condition cold, dry air, and, to move greater air volumes in response to higher energetic requirements.

On the rarity of big fierce carnivores and primacy of isolation and area: tracking large mammalian carnivore diversity on two isolated continents

by Christine Argot, Christopher Dickman, and Stephen Wroe

Proceedings of the Royal Society B: Biological Sciences, 2004

The hypothesis that low productivity has uniquely constrained Australia's large mammalian carnivo... more The hypothesis that low productivity has uniquely constrained Australia's large mammalian carnivore diversity, and by inference the biota in general, has become an influential backdrop to interpretations of ecology on the island continent. Whether low productivity has been primary impacts broadly on our understanding of mammalian biogeography, but investigation is complicated by two uniquely Australian features: isolation and the dominance of marsupials. However, until the great American biotic interchange (GABI), South America was also isolated and dominated by pouched carnivores. Here, we examine the low-productivity hypothesis empirically, by comparing large mammalian carnivore diversities in Australia and South America over the past 25 Myr. We find that pre-GABI diversity in Australia was generally comparable to or higher than diversity in South America. Post-GABI, South American diversity rose dramatically, pointing to isolation and phylogenetic constraint as primary influences. Landmass area is another important factor. Comparisons of diversity among the world's seven largest inhabited landmasses show that large mammalian hypercarnivore diversity in Australia approached levels predicted on the basis of landmass area in Late Pleistocene-Recent times, but large omnivore diversity was low. Large marsupial omnivores also appear to have been rare in South America. Isolation and competition with large terrestrial birds and cryptic omnivore taxa may have been more significant constraints in this respect. Relatively high diversity has been achieved in Late Quaternary America, possibly as a result of 'artificially' high immigration or origination rates, whereas that in contemporaneous Africa has been surprisingly poor. We conclude that isolation and landmass area, rather than productivity, are the primary constraints on large mammalian carnivore diversity. Our results quantify the rarity of large hypercarnivorous mammals worldwide.

High-Resolution Three-Dimensional Computer Simulation of Hominid Cranial Mechanics

by Darren Curnoe, Stephen Wroe, and Philip Clausen

In vivo data demonstrates that strain is not distributed uniformly on the surface of the primate ... more In vivo data demonstrates that strain is not distributed uniformly on the surface of the primate skull during feeding. However, in vivo studies are unable to identify or track changes in stress and strain throughout the whole structure. Finite element (FE) analysis, a powerful engineering tool long used to predict the performance of man-made devices, has the capacity to track stress/strain in three dimensions (3-D) and, despite the time-consuming nature of model generation, FE has become an increasingly popular analytical device among biomechanists. Here, we apply the finite element method using sophisticated computer models to examine whether 3-D stress and strain distributions are nonuniform throughout the primate skull, as has been strongly suggested by 2-D in vivo strain analyses. Our simulations document steep internal stress/strain gradients , using models comprising up to three million tetrahedral finite elements and 3-D reconstructions of jaw adducting musculature with both cranium and mandible in correct anatomical position. Results are in broad concurrence with the suggestion that few regions of the hominid cranium are clearly optimized for routine feeding and also show that external stress/strain does not necessarily reflect internal distributions. Findings further suggest that the complex heterogeneity of bone in the skull may act to dissipate stress, but that consequently higher strain must be offset by additional strain energy. We hypothesize that, despite energetic costs, this system may lend adaptive advantage through enhancing the organism's ability to modify its behavior before reaching catastrophic failure in bony or dental structures.

The craniomandibular mechanics of being human "Data Supplement" Subject collections Email alerting service

by Darren Curnoe and Stephen Wroe

Citations to Advance online articles must include the digital object identifier (DOIs) and date o... more Citations to Advance online articles must include the digital object identifier (DOIs) and date of initial online articles are citable and establish publication priority; they are indexed by PubMed from initial publication. the paper journal (edited, typeset versions may be posted when available prior to final publication). Advance Advance online articles have been peer reviewed and accepted for publication but have not yet appeared in http://rspb.royalsocietypublishing.org/subscriptions

Human Remains from the Pleistocene-Holocene Transition of Southwest China Suggest a Complex Evolutionary History for East Asians

by Darren Curnoe, Paul Tacon, and Stephen Wroe

Background: Later Pleistocene human evolution in East Asia remains poorly understood owing to a s... more Background: Later Pleistocene human evolution in East Asia remains poorly understood owing to a scarcity of well described, reliably classified and accurately dated fossils. Southwest China has been identified from genetic research as a hotspot of human diversity, containing ancient mtDNA and Y-DNA lineages, and has yielded a number of human remains thought to derive from Pleistocene deposits. We have prepared, reconstructed, described and dated a new partial skull from a consolidated sediment block collected in 1979 from the site of Longlin Cave (Guangxi Province). We also undertook new excavations at Maludong (Yunnan Province) to clarify the stratigraphy and dating of a large sample of mostly undescribed human remains from the site.

Resolving the evolution of the mammalian middle ear using Bayesian inference

by Hector E. Ramírez-Chaves and Stephen Wroe

Background: The minute, finely-tuned ear ossicles of mammals arose through a spectacular evolutio... more Background: The minute, finely-tuned ear ossicles of mammals arose through a spectacular evolutionary transformation from their origins as a load-bearing jaw joint. This involved detachment from the postdentary trough of the mandible, and final separation from the dentary through resorption of Meckel's cartilage. Recent parsimony analyses of modern and fossil mammals imply up to seven independent postdentary trough losses or even reversals, which is unexpected given the complexity of these transformations. Here we employ the first model-based, probabilistic analysis of the evolution of the definitive mammalian middle ear, supported by virtual 3D erosion simulations to assess for potential fossil preservation artifacts. Results: Our results support a simple, biologically plausible scenario without reversals. The middle ear bones detach from the postdentary trough only twice among mammals, once each in the ancestors of therians and monotremes. Disappearance of Meckel's cartilage occurred independently in numerous lineages from the Late Jurassic to the Late Cretaceous. This final separation is recapitulated during early development of extant mammals, while the earlier-occurring disappearance of a postdentary trough is not. Conclusions: Our results therefore suggest a developmentally congruent and directional two-step scenario, in which the parallel uncoupling of the auditory and feeding systems in northern and southern hemisphere mammals underpinned further specialization in both lineages. Until ~168 Ma, all known mammals retained attached middle ear bones, yet all groups that diversified from ~163 Ma onwards had lost the postdentary trough, emphasizing the adaptive significance of this transformation.

Cranial shape variation and phylogenetic relationships of extinct and extant Old World leaf-nosed bats

by Camilo López Aguirre, Karen Black, and Stephen Wroe

The leaf-nosed bats in Hipposideridae and Rhinonycteridae currently have an Old World tropical to... more The leaf-nosed bats in Hipposideridae and Rhinonycteridae currently have an Old World tropical to subtropical distribution, with a fossil record extending back to the middle Eocene of Europe. The Riversleigh World Heritage fossil site in northwestern Queensland constitutes a particularly rich archive of faunal diversity for Old World leaf-nosed bats, having yielded more than 20 species. We used 2D geometric morphometrics to quantify cranial shape in hipposiderids and rhinonycterids, with the aim of referring unallocated fossil species, particularly from Riversleigh, to each family within a phylogenetic framework, and using a quantitative approach to reconstruct cranial shape for key clades in these Old World radiations. Our sample comprised 21 extant hipposiderids and rhinonycterids, 1 megadermatid and 1 rhinolophid, in which 31 landmarks were placed in lateral and ventral views, and five measurements were taken in dorsal view. The phylogeny used as the framework for this study was based on an analysis of 64 discrete morphological characters from the dentition, cranium and postcranium scored for 42 extant and fossil hipposiderids and rhinonycterids and five outgroup taxa (rhinolophids and megadermatids). The phylogenetic analysis was conducted using maximum parsimony, with relationships among selected extant taxa constrained to match the results of recent comprehensive molecular studies. Our phylogenetic results suggest that the Riversleigh leaf-nosed bats probably do not represent an endemic Australian radiation, with fossil species spread throughout the tree and several with sister-group relationships with non-Australian taxa. Discriminant analyses (DA) conducted separately on each dataset resulted in cross-validated classification success ranging from 61.9% for ventral landmarks to 71.4% for lateral landmarks. Classification of the original grouped cases resulted in success of 81% for each dataset. Of the eight fossil taxa included as unknowns in the DA, six were found to be assigned to the same group as recovered by the phylogenetic analysis. From our results, we assign the Riversleigh Miocene species Archerops annectens, Brachipposideros watsoni, Brevipalatus mcculloughi, Rhinonicteris tedfordi and Xenorhinos halli to Rhinonycteridae, and Riversleigha williamsi and Hipposideros bernardsigei to Hipposideridae. Our results support Pseudorhinolophus bouziguensis, from the early Miocene of Bouzigues in southern France, as belonging to Hipposideridae, and probably Hipposideros. The reconstructed ancestor of hipposiderids was distinguished from that of the rhinonycterids by having a shorter rostrum, and less of a distinction between the rostrum and braincase.

Mammalian development does not recapitulate suspected key transformations in the evolutionary detachment of the mammalian middle ear

The ectotympanic, malleus and incus of the developing mammalian middle ear (ME) are initially att... more The ectotympanic, malleus and incus of the developing mammalian middle ear (ME) are initially attached to the dentary via Meckel's cartilage, betraying their origins from the primary jaw joint of land vertebrates. This recapitulation has prompted mostly unquantified suggestions that several suspected—but similarly unquantified—key evolutionary transformations leading to the mammalian ME are recapitulated in development, through negative allometry and posterior/medial displacement of ME bones relative to the jaw joint. Here we show, using mCT reconstructions, that neither allometric nor topological change is quantifiable in the pre-detachment ME development of six marsu-pials and two monotremes. Also, differential ME positioning in the two monotreme species is not recapitulated. This challenges the developmental prerequisites of widely cited evolutionary scenarios of definitive mammalian middle ear (DMME) evolution, highlighting the requirement for further fossil evidence to test these hypotheses. Possible association between rear molar eruption, full ME ossification and ME detachment in marsupials suggests functional divergence between dentary and ME as a trigger for developmental , and possibly also evolutionary, ME detachment. The stable positioning of the dentary and ME supports suggestions that a 'partial mammalian middle ear' as found in many mammaliaforms—probably with a cartilaginous Meckel's cartilage—represents the only developmentally plausible evolutionary DMME precursor.

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

by Stephen Wroe and Paul Scofield

The moa (Dinornithiformes) are large to gigantic extinct terrestrial birds of New Zealand. Knowle... more 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 bio-mechanical 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 biomecha-nical performance between the extant emu (Dromaius novaehollandiae) and extinct upland moa (Megalapteryx didinus) based on similarities in mandibu-lar 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.

To Meat or Not to Meat? New Perspectives on Neanderthal Ecology

by Stefano Benazzi, Andrea Picin, and Stephen Wroe

Neanderthals have been commonly depicted as top predators who met their nutritional needs by focu... more Neanderthals have been commonly depicted as top predators who met their nutritional needs by focusing entirely on meat. This information mostly derives from faunal assemblage analyses and stable isotope studies: methods that tend to underestimate plant consumption and overestimate the intake of animal proteins. Several studies in fact demonstrate that there is a physiological limit to the amount of animal proteins that can be consumed: exceeding these values causes protein toxicity that can be particularly dangerous to pregnant women and newborns. Consequently, to avoid food poisoning from meat-based diets, Neander-thals must have incorporated alternative food sources in their daily diets, including plant materials as well. Yrbk Phys Anthropol 156:43–71, 2015. V C 2014 American Association of Physical Anthropologists In this manuscript, we review traditional as well as more recent approaches for reconstructing the diet in past human populations, and we show how new archaeological discoveries and innovative methods are changing our views of Neanderthal ecology and behavior. We further underline the importance of reconstructing Nean-derthal environments derived from palaeoecological data to better understand and interpret the dietary evidence obtained by these methods. Finally, since the intake of specific foods can be invisible to certain techniques and detect by others, we suggest using a more holistic approach by integrating the findings of more than one method. Such comprehensive analyses would enable the reconstruction of the whole dietary spectrum, which is particularly important for species like Neanderthal, who lived under severe and unstable climatic conditions. Neanderthals are undoubtedly the most studied and best-known group in the human fossil record. Despite that, for more than 100 years since their discovery, research on Neanderthal ecology, subsistence strategies, and diet have received remarkably little attention (Ready, 2010). It is only with the emergence of new archeological disciplines and development of innovative analytical approaches in the 1960s, that scholars began to look at Neanderthal behavior and adaptations to their environment. Methods such as faunal analysis, lithic technology, and taphonomic studies progressively led to a general portrait that defined Neanderthals as a homogenous group, with similar nutritional needs typified by a reliance on the consumption of terrestrial animals. This idea was reinforced by the study of stable isotopes and Neanderthal anatomy. The general robusticity of Nean-derthal skeletons, with relatively short limbs and heavy trunks, has been interpreted as adaptation to cold stress environments that follow the ecogeographic principles of Bergmann's and Allen's rules (e.

Cranial Shape and the Modularity of Hybridization in Dingoes and Dogs; Hybridization Does Not Spell the End for Native Morphology

by Stephen Wroe and Mathew S Crowther

Australia's native wild dog, the dingo (Canis dingo), is threatened by hybridization with feral o... more Australia's native wild dog, the dingo (Canis dingo), is threatened by hybridization with feral or domestic dogs. In this study we provide the first comprehensive three dimensional geometric morphometric evaluation of cranial shape for dingoes, dogs and their hybrids. We introduce a novel framework to assess whether mod-ularity facilitates, or constrains, cranial shape change in hybridization. Our results show that hybrid and pure dingo morphology overlaps greatly, meaning that hybrids cannot be reliably distinguished from dingoes on the basis of cranial metrics. We find that dingo morphology is resistant, with observed hybrids exhibiting morphology closer to the dingo than to the parent group dog. We also find that that hybridization with dog breeds does not push the dingo cranial morphology towards the wolf phenotype. Disparity and integration analyses on the ten recovered modules provided empirical support for modularity facilitating shape change over short evolutionary time scales. However , our results show that this is may not be the case in hybridization events, which were not influenced by module integration or disparity levels. We conclude that although hybridization events may introduce breed dog DNA to the dingo population, the native cranial morphology, and therefore likely the feeding eco-niche, of the dingo population is resistant to change. Our results have implications for conservation and management of dingoes and, more broadly, for the influence of integration patterns over ecological time scales in relation to selection pressure.

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

by Stephen Wroe and Tracey Rogers

Thylacinidae is an extinct family of Australian and New Guinean marsupial carnivores, comprizing ... more 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.

Chronological overlap between humans and megafauna in Sahul (Pleistocene Australia–New Guinea): A review of the evidence

by Melanie Fillios and Stephen Wroe

Earth-Science Reviews, 2008

Over 60 faunal species disappeared from the Australian continent during the Middle-Late Pleistoce... more Over 60 faunal species disappeared from the Australian continent during the Middle-Late Pleistocene. Most of these animals were large to gigantic marsupials, birds and reptiles. A terminal extinction date of 46.4 kyr has been proposed for the megafauna, with all sites containing younger fossil megafauna dismissed by some researchers because of questions over stratigraphic integrity or chronologies. The timing of the extinctions is argued to be broadly coincident with estimates of first colonization of the continent by modern humans, and explanatory extinction models involving humans have subsequently gained currency. However there is considerable evidence to suggest that in some parts of the continent, people and some species of megafauna may have co-existed well beyond 46.4 kyr. In other places, such as Tasmania and the north of the continent, there is no known record of a human-megafauna temporal overlap. A review of the available evidence indicates that only 13 species of megafauna were extant on human arrival in Australia. The archaeology of this period indicates that rather than a focus on big game hunting or 'firestick farming', it was characterized by regional variability in subsistence strategies consistent with the range of environmental zones. At the present time there is no substantive argument for a terminal extinction date of 46.4 kyr, the current evidence indicating that there is no specific time period that correlates to any single mass extinction event. On the basis of available evidence arguments for either human or climatic causation are entirely circumstantial and implicitly require acceptance of many unproven assumptions. Claims to have eliminated climate as a primary driver are premature and the recent focus on delivering 'proof' of human causation in Pleistocene faunal extinctions diverts attention from achieving a better understanding of the differential impacts of climate change and short term climatic flux in a land of environmental extremes.

CONFIRMATION OF THYLACINUS FROM THE PLIOCENE CHINCHILLA LOCAL FAUNA

Large orb-webs adapted to maximise total biomass not rare, large prey

Scientific reports, 2015

Spider orb-webs are the ultimate anti-ballistic devices, capable of dissipating the relatively ma... more Spider orb-webs are the ultimate anti-ballistic devices, capable of dissipating the relatively massive kinetic energy of flying prey. Increased web size and prey stopping capacity have co-evolved in a number orb-web taxa, but the selective forces driving web size and performance increases are under debate. The rare, large prey hypothesis maintains that the energetic benefits of rare, very large prey are so much greater than the gains from smaller, more common prey that smaller prey are irrelevant for reproduction. Here, we integrate biophysical and ecological data and models to test a major prediction of the rare, large prey hypothesis, that selection should favour webs with increased stopping capacity and that large prey should comprise a significant proportion of prey stopped by a web. We find that larger webs indeed have a greater capacity to stop large prey. However, based on prey ecology, we also find that these large prey make up a tiny fraction of the total biomass (=energy) ...

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

Proceedings. Biological sciences / The Royal Society, Jan 13, 2016

The moa (Dinornithiformes) are large to gigantic extinct terrestrial birds of New Zealand. Knowle... more 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 extan...

Ferrara et al 2011 - GWS vs GNS bite - J Biomechanics44

by Toni Ferrara, Victor Peddemors, Stephen Wroe, and Philip Clausen

Although a strong correlation between jaw mechanics and prey selection has been demonstrated in b... more Although a strong correlation between jaw mechanics and prey selection has been demonstrated in bony fishes (Osteichthyes), how jaw mechanics influence feeding performance in cartilaginous fishes (Chondrichthyes) remains unknown. Hence, tooth shape has been regarded as a primary predictor of feeding behavior in sharks. Here we apply Finite Element Analysis (FEA) to examine form and function in the jaws of two threatened shark species, the great white (Carcharodon carcharias) and the sandtiger (Carcharias taurus). These species possess characteristic tooth shapes believed to reflect dietary preferences. We show that the jaws of sandtigers and great whites are adapted for rapid closure and generation of maximum bite force, respectively, and that these functional differences are consistent with diet and dentition. Our results suggest that in both taxa, insertion of jaw adductor muscles on a central tendon functions to straighten and sustain muscle fibers to nearly orthogonal insertion angles as the mouth opens. We argue that this jaw muscle arrangement allows high bite forces to be maintained across a wider range of gape angles than observed in mammalian models. Finally, our data suggest that the jaws of sub-adult great whites are mechanically vulnerable when handling large prey. In addition to ontogenetic changes in dentition, further mineralization of the jaws may be required to effectively feed on marine mammals. Our study is the first comparative FEA of the jaws for any fish species. Results highlight the potential of FEA for testing previously intractable questions regarding feeding mechanisms in sharks and other vertebrates.

Computer simulations show that Neanderthal facial morphology represents adaptation to cold and high energy demands, but not heavy biting

by Jean-Jacques Hublin and Stephen Wroe

Research Cite this article: Wroe S et al. 2018 Computer simulations show that Neanderthal facial ... more Research Cite this article: Wroe S et al. 2018 Computer simulations show that Neanderthal facial morphology represents adaptation to cold and high energy demands, but not heavy biting. Proc. R. Soc. B 285: 20180085. http://dx. Three adaptive hypotheses have been forwarded to explain the distinctive Neanderthal face: (i) an improved ability to accommodate high anterior bite forces, (ii) more effective conditioning of cold and/or dry air and, (iii) adaptation to facilitate greater ventilatory demands. We test these hypotheses using three-dimensional models of Neanderthals, modern humans, and a close outgroup (Homo heidelbergensis), applying finite-element analysis (FEA) and computational fluid dynamics (CFD). This is the most comprehensive application of either approach applied to date and the first to include both. FEA reveals few differences between H. heidel-bergensis, modern humans, and Neanderthals in their capacities to sustain high anterior tooth loadings. CFD shows that the nasal cavities of Nean-derthals and especially modern humans condition air more efficiently than does that of H. heidelbergensis, suggesting that both evolved to better withstand cold and/or dry climates than less derived Homo. We further find that Neanderthals could move considerably more air through the nasal pathway than could H. heidelbergensis or modern humans, consistent with the propositions that, relative to our outgroup Homo, Neanderthal facial morphology evolved to reflect improved capacities to better condition cold, dry air, and, to move greater air volumes in response to higher energetic requirements.