Sean McMahon

Photo of Dr S McMahon
Dr S McMahon

Dr S McMahon

Reader in Astrobiology
Academic staff
James Clerk Maxwell Building (JCMB)
Room 1508

Sean is a member of the following School research institute and research areas:

Research interests

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.


2019-         Chancellor's Fellow (tenure-track), University of Edinburgh, UK

2017-2019 Marie Skłodowska-Curie Fellowship (D-BIOME), University of Edinburgh, UK

2014-2017 Postdoctoral Associate, Yale University, USA

2010-2014 PhD Geology, University of Aberdeen, UK

2006-2010 MEarthSci, St. Edmund Hall, Oxford, UK

Recent publications

  1. , and , Lethaia: An International Journal of Palaeontology and Stratigraphy, 57, 1, p. 1-11
  2. , , , and , Geological Magazine, 160, 10, p. 1946-1952
  3. , , , , , and , Astrobiology, 23, 11, p. 1202-1212
  4. , , , , , , , , , et al., Astrobiology, 23, 11, p. 1213-1227
  5. , , and , Astrobiology, 23, 11, p. 1228-1237