And so begins the blog.
I decided to write a blog after many late night thoughts of ‘mmm…that would be interesting to learn about. If only I had an outlet for my mini-researches…’ So here we are. Obviously, now that it is all set up and ready to go, all ideas for witterings have turned tail and flown.
Never mind – they will return again when I am not looking I’m sure. For now, I think a little introduction to what I should be spending my time thinking about – Early Life Palaeontology.
When people ask me what I do, I say ‘Palaeontology’. For most, this is dinosaurs, or what Ross from Friends does, or sometimes even Romans and Clay pipes (not really palaeontology at all). Whilst I am interested in all these things, they are not in fact what I spend my days doing. The peculiar and fascinating branch of palaeontology I deal with is almost entirely microsopic, very very old, and often deeply enigmatic.
Before the Roman clay pipes, before the dinosaurs, before trilobites, before, indeed, anything that you might recognise, there was life, and that life was fossilised. Animals first appeared at the Cambrian Explosion, 543 million years ago. The time before this is logically called the Precambrian, and it contains fossils of organisms that don’t resemble anything we know today, and of things so morphologically simple that they are hard to assign to anything. And yet, this enigmatic period is (in my opinion) one of the most exciting times in the evolution of life. Somehow, sometime, in the period between the formation of the Earth (4.56 billion years ago), and the sudden appearance of most animal phyla at the Cambrian explosion, the following had to happen:
- The origin of life – the transition from a purely chemical world to a biochemical one
- The first cell – often tied to the origin of life, as the simplest form of life may be defined as a bacterial cell
- The evolution of novel metabolic pathways, such as photosynthesis and oxygenic respiration
- The transition from a prokaryotic bacterial cell, containing no coherent nucleus and almost no other organelles, to a eukaryotic one. Eukaryotic cells contain a nucleus and organellles such as mitochondria, ribosomes and, in plants, chloroplasts.
- The introduction of new reproductive methods, most notably sexual reproduction
- The origin of muticellularity – where cells can perform different functions, and communication exists between them
In part, work on these important transitions must be dominated by theory. Changes in cellular metabolism are very difficult to detect in the geological record, even by geochemical proxy. But palaeontology can play a part. Contrary to the generally held belief that the best preservation of fossils is only seen after the Cambrian, there is an emerging picture of increasing preservation potential in as we go further back into the Precambrian. A combination of factors, including the absence of burrowing animals that disturb the sediment and lower oxygen levels, allowing slower oxic decay, means that before 543 million years ago, preservation of delicate structures, and especially cellular details, was exceptional.
If you look in the right places, and with the right tools, there are diverse cellular fossils in a wide range of different settings: from continental shelf and slope, to terrestrial lake systems. The study of these fascinating and critically important microfossils is part of the new and emerging field of early life palaeontology, which is working to piece together the story of life in its earliest stages.
And so this is what I do. Although my thesis technically binds me to a single fossil deposit (that of cells in a billion year old lake setting in northwest Scotland), the questions and exciting answers of the whole field are unavoidable.
Reconstruction of the Ediacaran enigmatic form, Dickinsonia. Copyright Leila Battison 2008