Late Devonian vertebrates from Siberia: a synchrotron microtomography study of bone bed material

Sammanfattning: This is an investigation of new vertebrate fossil material from the Late Devonian locality of Ivanovka, Uryup River, Siberia. This bone bed material, circa 375 million years in age, represents a unique opportunity to fill a gap in our understanding of Late Devonian diversity, biogeography, and vertebrate evolution: Siberia, at the time, was an independent continent, and yet its fauna remains virtually unknown in comparison with the other paleocontinents, Euramerica and Gondwana. Using synchrotron microtomographic scanning, a non-destructive technique that has never, to our knowledge, been applied to bone bed material, we obtained 3D image stacks that were then modelled to yield triangle meshes representing the bones in three dimensions. These meshes could then be identified, described, and interpreted. Many of the discovered bones belong to the poorly known genus Megistolepis Obruchev 1955, potentially allowing a radical increase in knowledge regarding this taxon. Other material includes lungfish and possible fragments of limbed tetrapods, though the evidence of the latter is scarce. A discussion of the advantages and disadvantages of synchrotron microtomography for the study of bone bed material concludes the paper.