The exceptionally preserved Fezouata Biota from the Lower Ordovician of Morocco: a unique window into the Cambro-Ordovician faunal transition

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The exceptionally preserved Fezouata Biota from the Lower Ordovician of Morocco: a unique window into the Cambro-Ordovician faunal transitionDerek Briggs, EAR-1053247Yale UniversityABSTRACTExceptionally preserved biotas, which preserve more than just the hard shells of marine animals, offer critical insights into the history of life. Such biotas are relatively common in rocks of Cambrian age, but our knowledge of life during the period that follows, the Ordovician, is almost entirely based on the evidence of shells alone. This situation has improved dramatically with the discovery of the Fezouata Biota in south-eastern Morocco ? the first early Ordovician exceptionally preserved fossil assemblage from a normal, open marine setting. These Ordovician animals show considerable diversity and contain a large number of forms typical of older Cambrian Burgess Shale-type deposits as well as more modern looking creatures. These findings show that the apparent disappearance of Burgess Shale-type fossils after the Middle Cambrian is not a result of extinction and replacement, but simply a reflection of the rarity of suitable settings for their preservation in Ordovician rocks. New discoveries in Morocco indicate that animals characteristic of the Cambrian continued to have a considerable impact on the biodiversity and ecology of marine communities more than 20 million years later, into the Ordovician. In addition, the presence of a number of advanced animals, like horseshoe crabs, in the Fezouata Biota indicates that these groups radiated much earlier than we knew, before the beginning of the Ordovician. The new Moroccoan discoveries will allow us to explore whether the diversification of major animal groups during the Cambrian (the Cambrian Explosion) and the subsequent Ordovician radiation (the Great Ordovician Biodiversification Event) were separate events, or simply a continuation of the same process. In addition we will carry out field-work and analyses of specimens to determine the environments of deposition and processes leading to the preservation of the soft-bodied fossils, allowing us to predict where new examples are likely to be found in the future. The project will provide unique learning opportunities for graduate students through interdisciplinary research in an overseas area of spectacular exposure. It will enrich courses on the history of life for non-major undergraduates and on exceptional preservation for graduates. The Moroccan fossils will be the subject of a temporary exhibit at the Yale Peabody Museum of Natural History, and of Museum webpages for the general public. They will continue to attract the attention of the wider media. The project will involve collaboration with researchers and students from many nations.