The enigmatic early vertebrate clade Rhenanida and the evolution of vertebrate reproductive modes

The Gogo fish, Eastmanosteus skull against a white background

The Gogo fish, Eastmanosteus © The Trustees of the Natural History Museum, London

The Rhenanida (Devonian) are an enigmatic group of fossil placoderms (early jawed vertebrates) that lived about 410 million years ago. 

Their ray-like appearances shows evidence of early functional diversification in jawed vertebrates. Despite being known from a number of articulated and complete fossils, rhenanids remain a mystery as to their evolutionary relationships.

Nevertheless, because of the completeness of many of their fossils, rhenanids have the potential inform our understanding of the evolution of jaws and teeth, the skull, paired appendages, and sexual reproductive structures.

This project will use exceptionally preserved fossil rhenanids combined with digital imaging techniques, like radiography and computed tomography (CT), and computational phylogenetics to investigate and resolve the anatomy and relationships of the rhenanids. This will be used to address questions of how early jawed vertebrate anatomical, reproductive, and functional diversity arose.

The Rhenanida include a small number of genera characterized by unusual and understudied cranial morphology, generally described before the advent of CT methods. This project will examine the following genera: Jagorina, Gemuendina, and Asterosteus on the basis of excellent articulated fossil material.

Fossils of Gemuendina, in particular, are often complete from snout to tip of tail, and include morphological details of the front and hind fins—which can be used to inform our understanding of the earliest fin morphologies, as well as the timing and origin of internal fertilisation structures (i.e. pelvic claspers).

This new data will be 3D volume rendered and used to (re)describe these taxa, plus build a morphological database for a new phylogenetic analysis to resolve the position of rhenanids within early jawed vertebrates. The latter will allow the evolution of various cranial and postcranial characters to be  evaluated during this important period of vertebrate evolution.

Jagorina and Gemuendina will be borrowed for study (MDB, Georg-August Universität, Göttingen) in the Department of Earth Sciences, Natural History Museum (macrophotography, radiography), with CT-scanning being performed at Core Research Labs, Natural History Museum. 3D volume rendering and visualization will be performed at Imperial and the Natural History Museum, using computers, programs (Avizo 9.0; Materialise Mimics 19) and drawing pads, specimen photography and examination space provided by the co-supervisors.

How to apply

Apply for this course through the Science and Solutions for a Changing Planet Doctoral Training Partnership website

The deadline for applications is 4 January 2021.

Apply for this project

Read more about the Science and Solutions for a Changing Planet Doctoral Training Partnership (SSCP DTP)

Application deadline: 4 January 2021

Any questions?

If you have any questions about the project please contact

Lead supervisor: Dr Martin Brazeau, Imperial College London

Supervisors

Natural History Museum

Dr Zerina Johanson

Science and Solutions for a Changing Planet (SSCP) doctoral training partnership

This is a joint project between The Science and Solutions for a Changing Planet (SSCP) Doctoral Training Partnership at Imperial College London and The Natural History Museum.

Funded by