Evolutionary Milestones

Certain milestones punctuate the history of life. For example, after abiogenesis and the first living organisms, early evolution saw the development of organised cells (those with a nucleus, in a group called eukaryotes), the first ecological interactions between different species, and the events that led to the incorporation of mitochondria and other organelles into eukaryote cells.

Sometime after 1 billion years ago, many organisms independently became multicellular, animals started to include hard parts in their body plan (and rapidly diversify), and plants, then animals, joined unicellular organisms living on land. Looking into the fossil record we can directly study these events. Doing so allows us to better understand the origin of evolutionary novelties, the interactions between the life and the earth through geological time, and the timing of deep branches in the tree of life.

We use novel techniques to study these major events. We combine high resolution tomography to reveal fossils’ three-dimensional form, with geochemical analyses based on X-ray fluorescence and absorption spectroscopy, fourier transform infrared spectroscopy and pyrolysis gas chromatography mass spectrometry.

This is carried out alongide analysis of evolutionary relationships (cladistics). Using these techniques, we can untangle the competing influences of taphonomy and preservation on our understanding of evolution in deep time.

Our current work on such milestones includes studies on:

• The organic geochemistry of ancient bacterial mats
• The earliest unicellular organisms that lived on land and their ecological interactions
• The earliest biomineralising animals
• The nature of the Cambrian explosion
• Early land animals, including the origins and early evolution of insects and arachnids.

Future studies will expand on these topics, and develop new techniques to retrieve more information from the fossil record, including the computer modelling of evolution over palaeontological timescales.