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Stig Walsh is Senior Curator of Vertebrate Palaeobiology.
Dr Stig Walsh came to National Museums Scotland from the Natural History Museum (London) at the start of 2009. Dr Walsh’s research uses X-ray micro computed-tomographic (µCT) techniques to investigate the evolution of the vertebrate brain and senses, a branch of palaeobiology known as ‘palaeoneurology’.
Nerve and sensory structures rarely fossilise, so palaeoneurology must rely on information recorded by the bone associated with the structures in life. This evidence, such as the relative size of parts of the brain cavity, the diameter of nerve canals and the form of other bony anatomical structures such as the inner ear, can provide insight into the behaviour and sensory abilities of extinct animals.
Current approaches in palaeoneurology apply numerical modelling to the neurosensory structures of living species – in which behaviour and sensory abilities are known – to interpret the same structures preserved in fossils. Such research has tended to concentrate on the evolution of specific sensory modalities. For instance, the evolution of balance in a particular group is normally investigated by analysing the form of the inner ear in isolation. However, vertebrate balance is controlled via a dynamic system that integrates vestibular, visual and proprioceptive signals through plastic processing in the cerebellum.
Dr Walsh’s research has now moved towards finding approaches that can integrate multiple lines of evidence in order to understand how the vertebrate brain and senses have evolved over time.
Foffa, D., Dunne, E.M., Nesbitt, S.J., Butler, R.J, Fraser, N.C., Brusatte, S.L., Farnsworth, A., Lunt, D.J., Valdes, P.J., Walsh, S. & Barrett, P.M. 2022. Scleromochlus and the early evolution of Pterosauromorpha. Nature 610: 313-318. https://doi.org/10.1038/s41586-022-05284-x
Jones, M.E.H., Benson, R.B.J., Skutschas, P., Hill, L., Schmitt, A.D., Walsh, S.A., Evans, S.E. 2022. Middle Jurassic fossils document an early stage in salamander evolution. Proceedings of the National Academy of Sciences 119 (30): https://doi.org/10.1073/pnas.2114100119
Choiniere, J.N., Neenan, J.M., Schmitz, L., Ford, D.P., Chapelle, K.E.J., Balanoff, A.M., Sipla, J.S., Georgi, J.A., Walsh, S.A., Norell, M.A., Xu, X., Clark, J.M., Benson, R.B.J. 2021. Evolution of vision and hearing modalities in theropod dinosaurs. Science 372: 610-613. https://doi.org/10.1126/science.abe7941
Ksepka D., Balanoff A., Smith A., Bever G., Bhullar B.-A., Bourdon E., Braun E., Burleigh J. G., Clarke J., Colbert M., Corfield, J., Degrange F., De Pietri V., Early C., Field D., Gignac P., Gold E., Kimball R., Kawabe S., Lefebvre L., Marugán-Lobón J., Mongle C., Morhardt A., Norell M., Ridgely R., Rothman R., Scofield P., Tambussi C., Torres C., van Tuinen M., Walsh S. et al. 2020. Tempo and Pattern of Avian Brain Size Evolution. Current Biology 30: 1-11. https://doi.org/10.1016/j.cub.2020.03.060.
Schwab, J.A., Young, M.T., Neenan, J.M., Walsh, S.A. et al. 2020. Inner ear sensory system changes as extinct crocodylomorphs transitioned from land to water. Proceedings of the National Academy of Sciences: https://doi.org/10.1073/pnas.2002146117.
Benson, R. B. J., Starmer-Jones, E., Close, R. A. & Walsh, S. A. 2017. Comparative analysis of vestibular ecomorphology in birds. Journal of Anatomy 231: 990-1018. https://doi.org/10.1111/joa.12726.
Walsh, S. A., Milner, A.C. and Bourdon, E. 2016. A reappraisal of Cerebavis cenomanica (Aves, Ornithurae), from Melovatka, Russia. Journal of Anatomy 229: 215-227. https://doi.org/10.1111/joa.12406.
Walsh, S. A., Iwaniuk, A. N., Knoll M. A., Bourdon, E., Barrett, P. M., Milner, A. C., Nudds, R., Abel, R. L. & Dello Sterpaio, P. 2013. Avian cerebellar floccular fossa size is not a proxy for flying ability in birds. PLoS ONE 8 (6): e67176. https://doi.org/10.1371/journal.pone.0067176.
Walsh, S. A. & Milner, A. C. 2011. Halcyornis toliapicus (Aves: Lower Eocene, England) indicates advanced neuromorphology in Mesozoic Neornithes. Journal of Systematic Palaeontology 9 (1): 173-181.
Walsh, S. A., Barrett, P. M., Milner, A. C., Manley, G., & Witmer, L. M. 2009. Inner ear anatomy is a proxy for deducing auditory capability and behaviour in reptiles and birds. Proceedings of the Royal Society B 276: 1355-1360.
For further publications see the National Museums Scotland Research Repository.
Discover dinosaurs with our Senior Curator of Vertebrate Palaeobiology, Stig Walsh.Blog posts by Stig Walsh