1,721,138 research outputs found
Cranial mechanics and feeding in <i>Tyrannosaurus rex</i>
No full textRayfield, Emily J. (2004): Cranial mechanics and feeding in Tyrannosaurus rex. Proceedings of the Royal Society of London, Series B 271 (1547): 1451-1459, DOI: 10.1098/rspb.2004.275
Figure 1 in Cranial mechanics and feeding in Tyrannosaurus rex
No full textFigure 1. Tyrannosaurus rex skull and FEM. (a) Skull of BHM 3033, left lateral view; and (b) 2D FE-mesh of BHM 3033 depicting skull as 'fused' without mobile sutures. Grey areas indicate surfaces constrained from moving in all translatory directions, arrows indicate direction of bite force applied to all teeth, either vertical or horizontal 'tearing'. Abbreviations: aof, antorbital fenestra; en, external naris; j, jugal; l, lacrimal; ltf, lower temporal fenestra; m, maxilla, n, nasals; or, orbit; p, premaxilla; po, postorbital; pt, pterygoid; q, quadrate; qj, quadratojugal; sq, squamosal. Scale bar 10 cm.Published as part of Rayfield, Emily J., 2004, Cranial mechanics and feeding in Tyrannosaurus rex, pp. 1451-1459 in Proceedings of the Royal Society of London, Series B 271 (1547) on page 1452, DOI: 10.1098/rspb.2004.2755, http://zenodo.org/record/373673
Figure 3 in Cranial mechanics and feeding in Tyrannosaurus rex
No full textFigure 3. Stress in the fused FE Tyrannosaurus rex skull model generated by vertical biting (left column) or tearing (right column). (a) Principal stress 3 [P3], compressive stress; (b) P1 tensile stress; (c) shear stress; (d) P3 compressive stress; (e) P1 tensile stress; and (f) shear stress. Divergent arrows indicate orientation of tensile stress trajectories; convergent arrows indicate orientation of compressive stress trajectories. Units are Pa or Nm‾2. See electronic Appendix C for strain plots.Published as part of Rayfield, Emily J., 2004, Cranial mechanics and feeding in Tyrannosaurus rex, pp. 1451-1459 in Proceedings of the Royal Society of London, Series B 271 (1547) on page 1454, DOI: 10.1098/rspb.2004.2755, http://zenodo.org/record/373673
Figure 2 in Cranial mechanics and feeding in Tyrannosaurus rex
No full textFigure 2. Sutural morphology and mobility. (a) Postorbital–jugal suture in Tyrannosaurus rex; (b) maxilla–jugal suture in T. rex; (c) 2D FEM of T. rex skull with mobile postorbital–jugal contact; and (d) 2D FEM of T. rex skull with mobile maxillajugal contact. Double-headed arrows indicate direction of slight adjustive movement at suture. Single-headed arrows indicate location of 'suture' in FE-mesh. Illustrations after BHM 3033. Grey areas and abbreviations as defined in figure 1; pal, palatine.Published as part of Rayfield, Emily J., 2004, Cranial mechanics and feeding in Tyrannosaurus rex, pp. 1451-1459 in Proceedings of the Royal Society of London, Series B 271 (1547) on page 1453, DOI: 10.1098/rspb.2004.2755, http://zenodo.org/record/373673
Figure 4 in Neurocranial osteology and systematic relationships of Varanus (Megalania) prisca Owen, 1859 (Squamata: Varanidae)
No full textFigure 4. Stereopairs of the otic region of (A) Varanus prisca (BMNH 39965) in left ventrolateral view, (B) Varanus komodoensis (USNM 228163), and (C) Varanus salvator (ROMV-R 1040) in right ventrolateral views. Scale bar: 1 cm. Anatomical abbreviations are defined in Appendix 2.Published as part of Head, Jason J., Barrett Fls, Paul M. & Rayfield, Emily J., 2009, Neurocranial osteology and systematic relationships of Varanus (Megalania) prisca Owen, 1859 (Squamata: Varanidae), pp. 445-457 in Zoological Journal of the Linnean Society 155 (2) on page 451, DOI: 10.1111/j.1096-3642.2008.00448.x, http://zenodo.org/record/544470
Figure 1 in Neurocranial osteology and systematic relationships of Varanus (Megalania) prisca Owen, 1859 (Squamata: Varanidae)
No full textFigure 1. Neurocranium of Varanus prisca (BMNH 39965) in dorsal (A), ventral (B), anterior (C), and left lateral (D) views. Scale bar: 5 cm. Anatomical abbreviations are defined in Appendix 2.Published as part of Head, Jason J., Barrett Fls, Paul M. & Rayfield, Emily J., 2009, Neurocranial osteology and systematic relationships of Varanus (Megalania) prisca Owen, 1859 (Squamata: Varanidae), pp. 445-457 in Zoological Journal of the Linnean Society 155 (2) on page 448, DOI: 10.1111/j.1096-3642.2008.00448.x, http://zenodo.org/record/544470
Owen, 1859 (Squamata: Varanidae)
No full textHead, Jason J., Barrett Fls, Paul M., Rayfield, Emily J. (2009): Neurocranial osteology and systematic relationships of Varanus (Megalania) prisca Owen, 1859 (Squamata: Varanidae). Zoological Journal of the Linnean Society 155 (2): 445-457, DOI: 10.1111/j.1096-3642.2008.00448.x, URL: https://academic.oup.com/zoolinnean/article-lookup/doi/10.1111/j.1096-3642.2008.00448.
Figure 10 in The braincase, brain and palaeobiology of the basal sauropodomorph dinosaur Thecodontosaurus antiquus
No full textFigure 10. Evolution of endocranial morphology in Sauropodomorpha. Endocasts are in lateral view and not to scale. Abbreviations: asc, anterior semicircular canal; fl, floccular lobe; laby, endosseous labyrinth. The simplified phylogeny of Sauropodomorpha is based on the studies by Remes et al. (2009), Otero & Pol (2013), Langer et al. (2019) and McPhee et al. (2020). Saturnalia and Plateosaurus endocasts are from the study by Bronzati et al. (2017); Spinophorosaurus endocast is from the study by Knoll et al. (2012). The phylogenetic tree was edited in ITOL v.5 (https://itol.embl.de). Silhouettes are from http://phylopic.orgPublished as part of Ballell, Antonio, King, J Logan, Neenan, James M, Rayfield, Emily J & Benton, Michael J, 2021, The braincase, brain and palaeobiology of the basal sauropodomorph dinosaur Thecodontosaurus antiquus, pp. 541-562 in Zoological Journal of the Linnean Society 193 (2) on page 557, DOI: 10.1093/zoolinnean/zlaa157, http://zenodo.org/record/553061
Dietary specializations and diversity in feeding ecology of the earliest stem mammals
No full textThe origin and radiation of mammals are key events in the history of life, with fossils placing the origin at 220 million years ago, in the Late Triassic period1. The earliest mammals, representing the first 50 million years of their evolution and including the most basal taxa, are widely considered to be generalized insectivores1, 2. This implies that the first phase of the mammalian radiation—associated with the appearance in the fossil record of important innovations such as heterodont dentition, diphyodonty and the dentary–squamosal jaw joint1, 3—was decoupled from ecomorphological diversification2, 4. Finds of exceptionally complete specimens of later Mesozoic mammals have revealed greater ecomorphological diversity than previously suspected, including adaptations for swimming, burrowing, digging and even gliding2, 5, 6, but such well-preserved fossils of earlier mammals do not exist1, and robust analysis of their ecomorphological diversity has previously been lacking. Here we present the results of an integrated analysis, using synchrotron X-ray tomography and analyses of biomechanics, finite element models and tooth microwear textures. We find significant differences in function and dietary ecology between two of the earliest mammaliaform taxa, Morganucodon and Kuehneotherium—taxa that are central to the debate on mammalian evolution. Morganucodon possessed comparatively more forceful and robust jaws and consumed ‘harder’ prey, comparable to extant small-bodied mammals that eat considerable amounts of coleopterans. Kuehneotherium ingested a diet comparable to extant mixed feeders and specialists on ‘soft’ prey such as lepidopterans. Our results reveal previously hidden trophic specialization at the base of the mammalian radiation; hence even the earliest mammaliaforms were beginning to diversify—morphologically, functionally and ecologically. In contrast to the prevailing view2, 4, this pattern suggests that lineage splitting during the earliest stages of mammalian evolution was associated with ecomorphological specialization and niche partitioning
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