Large organisms whose fossils can reasonably be interpreted as animals did not evolve until late in the Ediacaran period, more than four billion years after the Earth formed. It’s sometimes claimed that these represented the first “complex life” but there’s really nothing simple about bacteria, archaea, algae or fungi, which were already well established and hugely diverse. Nevertheless, early animals and animal-like organisms are obviously of special interest and significance for us humans. The Ediacarans are also aesthetically fascinating, almost sculpturally beautiful fossils, preserved in rare but spectacular assemblages dotted around the world. In previous (and some ongoing) collaborations with palaeontologists, I have contributed to studies of several aspects of Ediacaran life, with a particular focus on the biogeochemical pathways that preserved these fossils. Now, I’ve begun a new collaboration as a co-investigator on a Leverhulme Trust Research Project Grant led by Alex Liu at Cambridge (UK), seeking to answer a fundamental question about the Ediacarans: where did they go?
By the start of the Cambrian period 540 million years ago, the Ediacara biota had vanished. Were they wiped off the Earth by a mass extinction event? Were they gradually replaced as Cambrian organisms invaded their turf? Or did they persist into the Cambrian but disappear from the fossil record simply because conditions were no longer favourable for their fossilization? As Alex puts it on his new website, “inconsistency in the level of detail to which the depositional environments hosting Ediacaran fossils have been described and reconstructed around the world means that it is difficult to distinguish between these competing hypotheses.” This is the nut we want to crack. Beginning in October 2021, our Leverhulme Trust Research Project will bring together an international team of sedimentologists, palaeontologists, and experimental geobiologists in order to reconstruct what happened at the end of the Ediacaran period. Work like this is a privilege and I am much looking forward to it.