Animal origins: the mystery of Earth’s first complex life

Description

For the vast majority of Earth’s 4.5 billion year history, life on our planet has been microbial. In rocks around 580 million years old, the first fossils of large, complex animal life appear, and by around 520 million years ago these early animals had diversified into a wide range of more familiar groups (a pattern known as the Cambrian Explosion).

Fossils from this time are our only direct source of evidence for this crucial development in life history. Currently, most of our knowledge about this diversification of animal life comes from the fossilised remains of shells and other mineralized skeletal parts. Yet these represent just a small fraction of the total diversity of organisms, most of which were soft-bodied. This has been a major barrier to understanding how various animal groups first evolved, and how more familiar Cambrian fossil animals relate to the older Ediacaran-age fossil animals. A potential solution to this problem can be found in the untapped record of ‘Small Carbonaceous Fossils’ (SCFs).

SCFs are microscopic fragments of soft-bodied animals and other organisms. This type of fossil has only recently been discovered and represents a completely new way to assess the fossil record of animals. Newly developed fossil extraction techniques have just begun to allow palaeontologists to exploit this untapped resource. When viewed under the microscope, SCFs reveal an exceptional level of detail, preserving minute features of the organisms which they are sourced from, that are impossible to see in ordinary fossils. Unlike other, much rarer types of soft-bodied preservation, SCFs are common, allowing us to track the early diversification of animals at a never before recorded level of resolution.

This project uses the new record of SCFs to reveal the microscopic anatomy of ancient early animals, and to track their early evolution. The project aims to enrich our understanding of how and when the first animal-dominated ecosystems evolved, an event which permanently changed ecology, evolution, the atmosphere and oceans, and ultimately led to the modern biosphere.