Terrestrialisation in vertebrates using evidence from synchrotron tomography

Supervisory Team  Dr Roger Benson, University of Oxford www.earth.ox.ac.uk/people/roger-benson  Dr Stig Walsh, National Museums of Scotland www.nms.ac.uk/collections-research/collections-departments/natural- sciences/palaeobiology/dr-stig-walsh

Key Words Palaeobiology, evolution, amniote origins

Overview Methodology Invasion of the land was a major transition in The project will use synchrotron tomographic data vertebrate evolution. A deep evolutionary of both Westlothiana and Casineria. These data divergence over 350 million years ago gave rise to provide unprecedentedly well-resolved 3D data on amphibians (salamanders, frogs, caecilians) and the skeletons of these animals, which will be used amniotes (mammals and reptiles, including birds) to generate 3D anatomical renderings at high (Hedges et al. 2015; Clack et al. 2016). Fossils resolution. Combined with examination of from this time are rare, but provide critical data on Carboniferous tetrapod fossils worldwide, the the anatomical transformations involved in resulting data will be used to revise our knowledge terrestrialisation, early ecological diversification, of phylogenetic relationships on the amniote stem and the timing of radiations that ultimately gave lineage and to assess the structure and functional rise to half of all living vertebrate species. adaptations of the limbs and skulls of these important transitional fossils. This work will Westlothiana and Casineria are important early advance our knowledge of amniote origins and of fossils that were originally reported as amniotes terrestrialisation in vertebrates. (Smithson 1989; Paton et al. 1999). Amniotes show significantly greater adaptation to terrestrial life than amphibians (e.g Janis & Keller 2001), and comprise many more species today. However, the specimens that would shed light on amniote Timeline origins have been difficult to study because of their Year 1: Literature review, training in 3D data delicate preservation in closed slabs of rock. visualisation/segmenting, virtual extraction of fossils from rocks using scan data. CT scanning. Years 2 and 3: Comparative anatomy, description, phylogenetic analysis. Functional interpretations. Synthesis.

Year 4: Data integration, thesis completion, papers for international journals/conference presentation.

Drawing of the skeleton of Westlothiana in its slab. Only surface details are visible. But much more is present within the rock. From Smithson (1989) Training & Skills Further Information 3D data visualisation/segmenting, comparative Dr Roger Benson anatomy, phylogenetics, palaeobiology [email protected]

References & Further Reading Clack JA 2012. Gaining Ground. Indiana University Press

Clack JA et al. 2016. Nature Ecology and Evolution 1, 0002

Hedges SB et al. 2015. Molecular Biology and Evolution 32, 835–845

Paton RL et al. 1999. Nature 398, 508–513;

Smithson TR 1989. Nature 314, 676–678;

Smithson TR et al. 1994. Transactions of the Royal Society of Edinburgh 84, 383–412.