The Digermul Peninsula - a window into the early diversification of animal life

The project period, 2014-2019, have given us five seasons of annual fieldwork on the Digermulen Peninsula in Tanafjord (Finnmark) where extensive sampling and collecting from the unique sedimentary layers is beginning to show us a more complete picture of changes occurring through the Ediacaran-Cambrian transition. This pivotal time in the evolution of complex organisms (ca 580 - 520 million years ago) is displayed almost in its entirety on the Digermulen Peninsula, making this a unique sedimentary section worldwide. Discoveries during these five years of field studies has confirmed the presence of a classic Ediacaran fossil assemblage in Scandinavia, sharing similarities with both the White Sea coast of Russia and parts of Newfoundland in Canada. While answering questions, they also pose a number of new ones, as we have added new data every year. Detailed studies in the field, literally meaning "crawling over the rocks", reveal fine structures that are tell-tale signs of the actual top of an ancient sea bottom. We are actually crawling on the bottom and not within the sediment. Spectacular finds in the last field season of the project in 2018 attest to the importance of close contact with the bedding surfaces. The earliest examples of good candidates for true trace fossils were uncovered ("when life became smart", organisms with the capacity to make controlled decisions and left traces of this on the ancient ocean floor), preserved together with delicate specimens of the problematic palaeopascichnid Orbisiana. Preserved through deep time in a manner allowing us to see those ecological interactions 550 million years later. Especially trace fossils represent short events in life, preserved through deep time. Pinpointing this level in the Ediacaran of the Digermulen Peninsula means that we are setting the stage for the "Agronomic Revolution" observed further up-section just after the Ediacaran-Cambrian transition. The "Agronomic revolution" marks a dramatic change in animal behaviour; animals are suddenly able to dig deep into the sediment, dragging nutrients and oxygen down into the bottom sediments, and forever changing life in the ocean. An important tool for us are microfossils, fossils that are "smaller than meets the eye". They allow correlation with similar rocks across the globe, but they also provide insight into the earliest forms of life, bacteria and their evolution. Sometimes our samples contain "oddballs" - one such, we are currently describing as bits and pieces from a larger multicellular eukaryote. One name for fossils such as these is "small carbonaceous fossils" or SCF for short. The project has during the last years sampled the Precambrian sediments specifically for SCFs, in order to reveal if there exists a cryptic record of complex metazoans. A cryptic record that then predates the Cambrian explosion and the appearance of external skeletons on a large scale. If so, this work in progress will be a fruitful contribution to understanding cause and effects of the Cambrian explosion. Extended sampling from the glacial levels of the Smalfjord and Mortensnes Formation in combination with a new technique for dissolving the samples gives us important possibilities of understanding of how life survived these major Snowball Earth type glaciations. The bigger picture emerging of the sediments on the Digermulen Peninsula is that of unique preservation, where nearly uninterrupted sedimentation through roughly 200 million years shows especially the evolution of benthic bottom communities through the Ediacaran-Cambrian transition. Not only do communities emerge, but also, with every different type of trace fossil, a new behaviour and body plan unfolds itself. This evolution is visible in various steps, where we can use the concept of trace fossil zonation to its full, without major interruptions in time. The project has generated vast amounts of data from five years of sampling, analysis and publications are partly finished, but overall the work continues with several articles under progression.

The project has succeeded in maintaining a gender balance throughout the project period and have brought in female scientists into the project. The international palaeontological community has been brought to Tromsø through increased international collaboration, and placed northern Norway on the international palaeontological scene. Also increasing the collaborative network for the project participants, both within their own scientific discipline but also with other geological disciplines. Long term societal impact through the education and public outreach program of the project, increasing the awareness of local natural history and pride to help preserve it, starting already in schools. Also, with a gender balanced project shown especially young females that natural science is for everyone.

The remote and inaccessible Digermul Peninsula in Northern Norway expose more than 1500 m of siliciclastic sediments of nearly unprecedented preservation and completeness from a most dramatic time period in the history of life, the late Ediacaran-Ordovici an (roughly 100 Ma). Ediacara-type fossils were found here 20 years ago, the only occurrence in Scandinavia, and the area has recently revealed other spectacular discoveries. Trace fossil abundance is simply enormous, and we know from other contemporaneo us sequences just how important these are for understanding the evolution of benthic ecosystems in the Cambrian. Trace fossil assemblages on Digermulen across the Ediacaran-Cambrian transition have already given us new information on the timing of this ev ent here and the components involved. So far the shelly fossils sequence is less studied, but new olenellid trilobite associations may clarify the evolution of Early Cambrian trilobite sequences in Scandinavia. Furthermore, the trace and body fossil recor d may for the first time be tied together. Previous work by the team has already significantly changed our understanding of the succession, and especially the organic-walled microfossils have provided firm age constraints on the succession, shown potenti al for international correlation and thus timing of the evolution of primary producers. Following up on the faunal turnovers observed is the underlying geological history. Questions regarding provenance and cyclicity of sequences and parasequences need to be addressed to couple possible causes and causality. Digermulen scenery and geology is breathtaking and promises a spectacular backdrop for science education and public outreach. This is a vitalizing part of the project through the 4 years. Digermulen is ripe with opportunity, this is the first project to propose a dedicated multidisciplinary approach to study the unique sequence and its record of biotic changes through a critical time in the evolution of li