PhD: Uniting taphonomy and tomography to illuminate early actinopterygian evolution

Overview:

Living ray-finned fishes, which account for over half of all living vertebrate diversity (some 36,000 species), display anatomical innovations of the skeleton and soft tissues. As the living groups diverged from each other around 360 million years ago, fossils are vital for understanding their evolution. These deep evolutionary roots present a number of problems, however. Firstly, soft tissue rarely fossilises, and the processes by which soft tissue is preserved in the vertebrate fossil record are poorly understood. Secondly, fossil fishes are often preserved in dense rocks that are tricky to image using CT scanning and even trickier to digitally dissect. Together, these present a barrier to reconstructing anatomies and relationships at the base of the ray-finned fish tree of life.

Technological advances in CT scanning and synchrotron imaging have revolutionised work on early fossil fishes. Notable recent examples include the discovery of exceptionally preserved soft tissue anatomy: the heart of a Devonian (~380 million years old) placoderm (Trinajstic et al. 2022) and the brain of a Carboniferous (~319 million years old) ray-finned fish (Figueroa et al. 2022). Aside from representing novel preservational styles, these features provide key information regarding anatomical innovations deep in the vertebrate tree. Taphonomic studies in fishes are in their infancy (Sansom et al. 2013), and the mechanisms by which such delicate structures as the brain are preserved in fossils that are well over 300 million years old is far from clear. Despite these exceptional discoveries, many of the rocks that host these fossils have lithologies and geometries that make them challenging to CT scan. This project will combine tomographic techniques and taphonomic experiments to understand how neural soft tissue structures are preserved in fossils, investigate anatomical innovations revealed by fossilised soft tissues, and refine CT scanning practices for fossil specimens. This research will provide new insights into exceptional three-dimensional preservation of soft tissues in vertebrate fossils, as well as the use of CT scanning to investigate mechanisms of taphonomy and decay.

Training and skills:

Students will be awarded CENTA2 Training Credits (CTCs) for participation in CENTA2-provided and ‘free choice’ external training. One CTC equates to 1⁄2 day session and students must accrue 100 CTCs across the three years of their PhD.

The student will be trained in the entire CT workflow from selecting specimens to scanning to segmentation, comparative anatomy and description, taxonomic and phylogenetic analyses, statistical methods, and taphonomic experimental design. The student will also receive training in how to write and illustrate scientific papers, apply for grants and awards, present work at conferences and scientific meetings, and network with peers. There may also be opportunities for undergraduate teaching and research supervision. These form the basis of an outstanding skill set, combining traditional and state- of-the-art techniques, that will facilitate a successful research career for the student.

Further details:

Dr Sam Giles, University of Birmingham (s.giles.1@bham.ac.uk). We particularly encourage applications from backgrounds underrepresented in geology/palaeontology and allied subjects, and welcome informal enquiries.

If you wish to apply to the project, applications should include:

A CENTA application form, downloadable from: CENTA application
A CV with the names of at least two referees (preferably three and who can comment on your academic abilities)
The application should please completed via: https://sits.bham.ac.uk/lpages/LES068.htm. Please select Apply Now in the PhD Geography and Environmental Science (CENTA) section. Please quote CENTA23_B7 when completing the application form.
For further information on how to apply please visit https://centa.ac.uk/apply/how-to-apply/.

Funding Notes
Different support is available for “home-fees-eligible” and “international” students.
Successful home-fees-eligible candidates will receive:
• An annual stipend, set at £17,688 for 2022/23, paid directly to the student in monthly increments
• A research training support grant (RTSG) of £8,000, held at their host institution
• CASE studentships attract an additional £3500 contribution to the RTSG, held at their host institution
Successful international candidates will receive the above as well as a contribution to the university fees at the level of support for Home-fee-eligible students.
Successful home candidates will receive full university fees paid directly to the university.
References
Camilieri-Asch, V., Shaw, J.A., Mehnert, A., Yopak, K.E., Partridge, J.C. and Collin, S.P., 2020. Dicect: a valuable technique to study the nervous system of fish. Eneuro, 7(4). https://doi.org/10.1523/ENEURO.0076-20.2020
Figueroa, R.T., Goodvin, D., Kolmann, M.A., Coates, M.I., Caron, A.M., Friedman, M. and Giles, S., 2022. Exceptional fossil preservation and evolution of the ray-finned fish brain. bioRxiv. https://doi.org/10.1101/2022.06.04.492470
Sansom, R.S., Gabbott, S.E. and Purnell, M.A., 2013. Atlas of vertebrate decay: a visual and taphonomic guide to fossil interpretation. Palaeontology, 56(3), pp.457-474. https://doi.org/10.1111/pala.12037
Trinajstic, K., Long, J.A., Sanchez, S., Boisvert, C.A., Snitting, D., Tafforeau, P., Dupret, V., Clement, A.M., Currie, P.D., Roelofs, B. and Bevitt, J.J., 2022. Exceptional preservation of organs in Devonian placoderms from the Gogo lagerstätte. Science, 377(6612), pp.1311-1314. https://doi.org/10.1126/science.abf3289