Quantitative analyses of Ediacaran Ecosystems

Organisms have occupied the planet for at least the past 3.5 billion years, but only relatively recently have their fossil remains been large enough to see with the naked eye. The first properly macroscopic fossils turn up around 580 million years ago, in the middle of the Ediacaran Period, less than 50 million years before the appearance of recognizable animals and the conventional fossil record of shells, bones and burrows. The significance of the Ediacaran fossil record is that is provides a direct account of the transition from the exclusively microbial world of the first three billion years, to the conspicuously belated establishment of a recognizably modern biosphere. Unfortunately, the Ediacaran record is also profoundly problematic. Not only do we not know what these earliest large life-forms were related to, it is not even clear what kinds of things they were, or how they made a living. The aim of this research proposed here is to reconstruct the original community ecology of these fossils - how they interacted with one another and with their environment - with an eye to understanding their role in bringing about the modern world.

One of the advantages of studying Ediacaran macrofossils is that none of them moved during life, so their fossilized positions provide an exact account of their original spatial inter-relationships. By analysing these spatial data, it is possible extract a surprising amount of original ecological detail. Like trees in a forest, the distribution of Ediacaran fossils on bedding surfaces reflects the interplay of numerous effects including organism life-history, inter-specific competition and facilitation, and the physical environment. As such, these ecological processes can be reverse engineered using many of the sophisticated statistical and modelling techniques developed by modern forest ecologists. We have already demonstrated the potential of this approach with a recent paper in Nature, and now plan to apply it systematically to the earliest known Ediacaran macrofossils, the "Avalonian assemblage" - known almost exclusively from iconic occurrences in Charnwood Forest, Leicestershire and SE Newfoundland.

The research programme is divided into two main parts. The first is data collection. Here we plan to assemble a comprehensive database of high-resolution, digitized 3D images of all known Avalonian bedding surfaces preserving large populations (> 100 specimens) of macrofossils. Made possible by recent advances in laser-scanning technology, this will yield the precise size, position and orientation of ~20,000 fossils comprising 44 separate bedding-surface communities.

The second, and primary, focus of this project is to analyse these data for their primary ecological content. Using a range of complementary quantitative techniques, we plan to address three main issues in early Ediacaran ecology:

1) How did these organisms interact with their environment, and how much did these environmental interactions matter compared to organism reproduction? This is the subject of a longstanding debate in modern community ecology, and the Ediacaran record offers a unique view of the balance among the first large organisms.

2) What was the distribution of body-sizes in Ediacaran ecosystems and what ecological processes were responsible for their particular size-structure? In modern aquatic systems, body-size is directly related to predation and the feeding relationships of animals, but there is no evidence of predatory animals in any of these early macroscopic communities.

3) Did competition for resources within the overlying water-column dominate interactions between Avalonian organisms? This has often been promoted as a significant factor in Ediacaran ecology, but has never been quantitatively tested. Our analytical approach to this and other questions of Ediacaran ecology promise to shed significant new light on the origin of the modern biosphere.

There are three non-academic groups that will benefit from our research, and that we will target in our Pathways to Impact plan.

The Interested Public
Understanding the evolution of life on Earth has enormous public interest, and the Ediacaran transition to the modern biosphere is increasingly coming into the public consciousness. Most of the attention has been directed towards younger assemblages in Russia and Australia, but the earlier and arguably more important assemblages are here in the UK and in Newfoundland, Canada. We plan to raise Avalonian Ediacaran awareness in Cambridge through our in-house palaeontological Museum (over 100,000 visitors a year), and by putting the Ediacaran in context of the Cambrian explosion, for which the Cambridge palaeobiology group is world renowned. We are actively engaged with the Charnia Research Group, a group comprising of interested people from Natural England and local museums, local land owners and academics interested in Charnwood and Ediacaran palaeobiology. We will continue to work with this group throughout the project, keeping them updated on our research. In Canada we will work with the Mistaken Point Ecological Reserve visitors centre, to ensure that visitors are aware of our ongoing work and how it illuminates understanding of the fossils beds.

Educators
In Newfoundland we will host a one-day workshop for science teachers liaising with local academics, Mistaken Point Ecological Reserve staff and Parks Canada staff. This workshop will educate teachers and ensure they have the information and resources they need to educate their pupils about their own geological heritage and the global significance of Newfoundland Ediacaran fossils. The Coaker foundation, a local organisation based in Bonavista Peninsula, will help liaise with local educators.

Conservation
Avalonian bedding planes are very susceptible to erosion in Canada and human degradation in the UK. By documenting surfaces using 3D laser scans, they will be preserved in case of further damage. Furthermore, comparisons of the surface scans over longer time periods will enable policy makers, such as Parks Canada and Natural England to have a deeper understanding of the key causes of surface destruction, enabling efficient allocation of resources.