Unravelling early teleost relationships: diversification at the dawn of the most successful fish radiation

Atterby, Jake ORCID: 0000-0001-6619-0546 (2025). Unravelling early teleost relationships: diversification at the dawn of the most successful fish radiation. University of Birmingham. Ph.D.

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Abstract

Teleost fishes comprise more than 36,000 living vertebrate species and occupy a wide range of aquatic ecosystems. However, despite their overwhelming success, the anatomy and diversification of extinct Mesozoic taxa outside of the living radiation – stem teleosts – remain poorly understood. The teleost stem includes an abundance of charismatic Mesozoic fossil groups underpinned by centuries of study, such as pholidophorids, aspidorhynchids and pachycormids. But efforts to understand their interrelationships have been limited by several critical areas of uncertainty: key taxa allied to the stem are often omitted from phylogenetic investigations and the concealed potentially phylogenetically valuable internal anatomy of well-preserved specimens is rarely described. Consequently, there are multiple conflicting hypotheses of the phylogenetic arrangement of the teleost stem which obscures character distribution and patterns of diversification. This thesis presents comprehensive redescriptions of remarkably preserved historical specimens of iconic early neopterygian taxa using high resolution CT and synchrotron scanning. This has revealed novel anatomical insights across key taxa, including stem teleosts: Dorsetichthys bechei (Dorsetichthyidae) from Jurassic (Sinemurian) Lyme Regis, UK, Richmondichthys sweeti (Aspidorhynchidae) from the Cretaceous (Albian) Rolling Downs Group, Queensland, Australia and Pachycormus macropterus (Pachycormidae) from the Jurassic (Toarcian) Strawberry Bank Lagerstätte, Somerset, UK and enigmatic holostean taxa, “Aspidorhynchus” from the Jurassic (Bathonian) Great Oolite Group, Northamptonshire, UK. The anatomical insight obtained in this project has informed ecological inferences, new taxonomic appraisals of enigmatic specimens and a markedly strengthened phylogeny of the teleost stem and associated groups within Neopterygii.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):