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Cochleatina: an enigmatic Ediacaran–Cambrian survivor among small carbonaceous fossils (SCFs)

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Harvey, THP 
Bekker, A 
Butterfield, NJ 


jats:titleAbstract</jats:title>jats:pConspicuously few body‐fossil taxa are known to span the Ediacaran–Cambrian boundary, a pattern usually taken to signal either a terminal Proterozoic mass extinction, or taphonomic failure. We draw attention to the emerging record of small carbonaceous fossils (SCFs), which exhibit continuous preservation spanning this critical interval. Here we focus on the enigmatic SCF jats:italicCochleatina</jats:italic>, a morphologically complex coil‐shaped problematicum that ranges across the Ediacaran–Cambrian divide, and is potentially among the oldest fossil occurrences of metazoans. We report new material of jats:italicCochleatina canilovica</jats:italic> from the Ediacaran of Estonia and Ukraine, which offers new characters for assessing its palaeobiology. Significantly, new specimens include sets of three‐alike triplets of jats:italicCochleatina</jats:italic> adhering to organic sheets, suggesting a clustering habit, or grouping of elements within an individual during life; an important step in constraining the morphology and ecology of this Ediacaran–Cambrian problematicum. We present revised systematic descriptions for jats:italicCochleatina</jats:italic> and jats:italicC. canilovica</jats:italic>, and critically evaluate previous biological interpretations, drawing comparisons with metazoan, algal and protistan analogues. We reject hypotheses supporting jats:italicCochleatina</jats:italic> as a metazoan mouthpart, and suggest new grounds for viewing jats:italicCochleatina</jats:italic> as a potential multicomponent predator that trapped protists among microbial mats. Most occurrences are from Baltica, but we synthesize sporadic reports of jats:italicCochleatina</jats:italic> from other palaeocontinents, pointing to its global distribution during the latest jats:italic˜</jats:italic>10 myr of the Ediacaran and majority of the earliest Cambrian Fortunian Stage. As a rare example of an ‘Ediacaran survivor’, jats:italicCochleatina</jats:italic> highlights the broader significance of SCFs as a novel means of tracking evolutionary patterns through the Proterozoic–Phanerozoic transition.</jats:p>



Ediacaran-Cambrian survivor, oldest metazoan, Proterozoic mass extinction, small carbonaceous fossils, fossil problematica

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Natural Environment Research Council (NE/K005251/1)
NERC - grant NE/K005251/1