Sean McMahon



2023- Reader, University of Edinburgh, UK
2019-2023 Chancellor's Fellow, University of Edinburgh, UK
2019, Michaelmas   Visiting Fellow, Institute of Advanced Study, Durham University, UK
2017-2019   Marie Skłodowska-Curie Fellowship, University of Edinburgh, UK
2014-2017   Postdoctoral Associate, Briggs Lab, Yale University, USA
2010-2014   PhD Geology, University of Aberdeen, UK
2013, Summer   Planetary Biology Intern, NASA Ames Research Center, USA
2006-2010 MEarthSci, St Edmund Hall, University of Oxford, UK

Main interests

  • Microbial palaeontology
  • Fossilization processes on Earth and Mars
  • Life in subsurface habitats
  • Pseudofossils, dubiofossils, and the search for life on Mars

Responsibilities & affiliations

Co-director, UK Centre for Astrobiology

Programme Director, MSc Astrobiology & Planetary Sciences

Associate Editor, International Journal of Astrobiology

Royal Astronomical Society, Fellow (FRAS)

Geological Society and London, Fellow (FGS)

Palaeontological Association, Member

Astrobiology Society of Britain, Member

Undergraduate teaching

PGPH11108 Astrobiology Theory

PGPH11107 Astrobiology Methods

PHYS08051 Astrobiology

EASC10128 Planetary Science


Postgraduate teaching

Programme Director, MSc Astrobiology and Planetary Sciences

Open to PhD supervision enquiries?


Areas of interest for supervision

I supervise Senior Honours Projects (Physics), MPhys projects (Physics), MScR theses (Geobiology and Palaeontology) and PhDs (Physics, Geosciences). I occasionally supervise or co-supervise students in other Schools.

Research summary

How does planet Earth interact with its living biosphere over billions of years? My research explores how geological materials (rocks, minerals and sediments) select, shape and sustain communities of organisms, and how organisms in turn produce, degrade and modify rocky substrates to leave lasting traces in the geological record. The study of these interactions (geobiology) deepens our understanding of where we come from and enhances our ability to search for life elsewhere in the universe.

My recent and current work falls under three themes:

1. The deep biosphere, one of Earth's largest microbial biomes, which encompasses subseafloor and subterranean rocks and sediments. Here, my work aims to understand:  (1) the geological history of the deep biosphere in relation to the rest of the Earth–Life system;  (2) the fossil and geochemical record of deep life;  (3) controls on the habitability of subsurface environments and their potential to preserve fossils;  (4) whether these habitats and fossils tell us anything useful in the search for life on Mars.

2. Experimental taphonomy: the attempt to understand the processes that allow fossils to form by replicating them under controlled conditions in the laboratory. These processes intimately involve microbes, which can help explain how soft-bodied animal tissues and plants are able to be preserved. Similarly, experiments can be used to understand how microorganisms themselves become fossilized on Earth and (potentially) Mars.

3. Pseudofossils: structures formed by abiotic processes that resemble fossil organisms, and so can mislead researchers looking for evidence of life on Mars or the early Earth.

Affiliated research centres