Project highlights

  • Changes in the levels of fossil completeness may bias our understanding of the fossil record.
  • This project will quantify the quality of the fossil record and develop skeletal completeness indices specifically for early jawless fish.
  • Skeletal completeness indices will provide the basis for assessing the impact of biological and ecological parameters on the early jawless fish record.


The fossil record offers a rich resource with which to assess the timing and tempo of evolution among a wide variety of organisms. However, there is a question that underlies all of this work: just how complete is the fossil record? This question is one of the most fundamental posed by palaeontologists. Its answers have major ramifications for our understanding of deep time evolution, biogeography, ecology and diversity.

The early history of fish is undergoing a major revision at the present time, with character acquisition and evolution, taxonomic interrelationships and timing of divergence all receiving a renewed scrutiny. Each of these depend on an understanding of the quality of their fossil record. The ‘ostracoderms’ represent a loose agglomeration of armoured jawless fish that first appeared during the Ordovician and have a widespread distribution through the middle Palaeozoic. Through their time range they had a global distribution and became widespread in marine and freshwater enviroments. ‘Ostracoderms’ also comprise the bulk of the ancestral ‘stem-group’ that gives rise to the jawed vertebrates that dominate ecosystems at the present day. There are a number of curious aspects of the ‘ostracoderm’ fossil record, notably the different trajectories in their initial palaeoenvironmental range expansion (Sallan et al 2018) and a dramatic reduction in diversity in the end-Devonian which sees all of these hitherto prominent groups undergoing a terminal extinction. Understanding biases within their fossil record is critical in evaluating models for the rise and demise of these once diverse assemblages of jawless fish and their replacement by their jawed descendants.

New approaches to estimating fossil record completeness have recently been developed, and applied to the vertebrate record in both terrestrial (Mannion & Upchurch 2010) and marine (Tutin & Butler 2017) realms and are being modified and adapted to studies of fossil fish (Schnetz et al 2020).


CENTA Flagship

This is a CENTA Flagship Project


University of Birmingham


  • Dynamic Earth


Project investigator

  • Dr Ivan Sansom, University of Birmingham


  • Dr Sam Giles (Birmingham)
  • Dr Mike Howe (British Geological Survey)
  • Dr Zerina Johanson (Natural History Museum)
  • Prof Zhu Min (Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Beijing)

How to apply


The student will carry out a comprehensive museum/collections and literature review to extract and compile existing completeness datasets. Subsequently, new completeness estimates will be generated for a broad range of ostracoderm clades, from both marine and freshwater environments. These estimates will primarily utilise an adapted version of the ‘skeletal completeness metric’ (SCM) that has been developed for use with fossil fish as part of a current CENTA studentship. A diverse range of statistical approaches will be applied to the resulting datasets in order to answer the project’s key questions.

Training and skills

The student will receive broad training in quantitative approaches to palaeobiology, including use of R software. Training will also be provided in jawless fish anatomy and systematics, stratigraphy, use of the Paleobiology Database, presentation and publication of scientific results, and public outreach. This training will be designed to prepare the student for a career in palaeobiological research at a university or museum.

The successful candidate will have a strong background in a relevant subject such as geology, palaeobiology, zoology, biology, or ecology. Demonstrable strong quantitative skills will be highly beneficial, as will experience in programming and use of relevant software.


Partners and collaboration

Dr Sansom has expertise in the study of early vertebrates, with particular emphasis on diversity during the Palaeozoic.

Dr Giles is an expert in the anatomy, relationships and macroevolution of Palaeozoic and Mesozoic fossil fishes.

Dr Howe heads the National Geological Repository (BGS – Hosting partner), studying curation and digitisation, and development of palaeontological/collections databases .

Dr Johanson is an expert on vertebrate evolution, spanning the fossil and recent record of fish, based at the Natural History Museum (L1 End User).

Prof Zhu Min is one of the world’s leading paleoichthyologists with a particular emphasis on Palaeozoic fish from China.

Further details

Dr Ivan Sansom

Applications need to be submitted via the University of Birmingham postgraduate portal,, by midnight 11.01.2021. Please first check whether the primary supervisor is within Geography, Earth and Environmental Sciences, or in Biosciences, and click on the corresponding PhD program on the application page.

This application should include

  • a brief cover letter, CV, and the contact details for at least two referees
  • a CENTA application form
  • the supervisor and title of the project you are applying for under the Research Information section of the application form.

Referee’s will be invited to submit their references once you submit your application, but we strongly encourage applicants to ensure referees are aware of your submission and expecting a reference request from us. Students are also encouraged to visit and explore the additional information available on the CENTA website.

This is a CENTA Flagship Project

These have been selected because the project meets specific characteristics such as CASE support, collaboration with our CENTA high-level end-users, diversity of the supervisory team, career development of the supervisory team, collaboration with one of our Research Centre Partners (BGS, CEH, NCEO, NCAS) or student co-designed project. These characteristics are a CENTA priority. Studentships associated with Flagship projects will be provided exactly the same level of support as all other studentships.

Possible timeline

Year 1

Data gathering, including determining the taxonomic range of jawless fish to be studied and to identify suitable primary sources for the project.  Training in the utility of the DeepBone database (data entry, exploration and data extraction). Development of completeness indices for ostracoderms.

Year 2

Commence data analyses, establish robust qualitative and quantitative methods where appropriate. Research visits to key collections. Integration of palaeoenvironmental/palaeogeographic distribution database and palaeogeographic maps (using GIS). Presentation of initial results at SVPCA.

Year 3

Data analysis, correcting for sampling bias and testing. Presentation of project results at Palaeontological Association Annual Meeting. Writing the thesis will take place during the final year, but papers will be published throughout the project.


Further reading

Gai, Z., Lu, L., Zhao, W. and Zhu, M. (2018) New polybranchiaspiform fishes (Agnatha: Galeaspida) from the Middle Palaeozoic of China and their ecomorphological implications. PLoS ONE 13(9): e0202217.

Mannion, P.D. and Upchurch, P. (2010) Completeness metrics and the quality of the sauropodomorph fossil record through geological and historical time. Paleobiology 36, 283–302. doi:10.1666/09008.1

Sallan, L., Friedman, M., Sansom, R.S., Bird, C., and Sansom, I.J. (2018) The nearshore cradle of early vertebrate diversification. Science 362, pp. 460-464.

Sansom, I.J. and Andreev, P.S. (2019) The Ordovician Enigma. In Johanson, Z., Underwood, C. and Richter, M. (eds) Evolution and Development of Fishes. Cambridge University Press

Sansom, R.S., Randle, E. and Donoghue, P.C.J. (2015) Discriminating signal from noise in the fossil record of early vertebrates reveals cryptic evolutionary history. Proc. R. Soc. B282: 20142245.

Smith, M.P., Donoghue, P.C.J. and Sansom, I.J. (2002) The spatial and temporal diversification of Early Palaeozoic vertebrates. In Crame, J.A. and Owen, A.W. (eds) Palaeobiogeography and biodiversity change: the Ordovician and Mesozoic–Cenozoic radiations pp. 69–83. London, UK: The Geological Society Special Publication 194.

Tutin, S.L. and Butler, R.J. (2017) The completeness of the fossil record of plesiosaurs, marine reptiles from the Mesozoic. Acta Palaeontologica Polonica 62 (3), 563-573 doi:



While collections access, in both the UK and overseas, is a critical component of this project, the timetable for this can be moved within the duration of the project and complimented or (in extremis) replaced by literature based work. The efficacy of a combined specimen and literature based approach in generating fossil fish completeness datasets is established through the current CENTA project being undertaken by Lisa Schnetz (University of Birmingham).