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16/04/18 Emilia Jarochowska (Friedrich-Alexander-University Erlangen-Nuremberg)

Conodonts: teeth from an alternative universe (à la Doua, salle Fontannes)
Quand ? Le 16/04/2018,
de 14:00 à 15:00
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Conodonts: teeth from an alternative universe

Conodonts are famously used as a prime geochemical archive in deep time studies, but how much do we know about their biology? Being the first vertebrates to have developed mineralized tissues, conodonts provide an insight into early skeletonization and the associated emergence of trophic networks. In this talk, I will focus on recent findings on conodont ecology and their ultrastructural adaptations.

Our research on the environmental distribution of conodonts indicate that many species were highly specialized to thrive in hypersaline, evaporitic basins. These settings serve as a taphonomic window into the highly complex spatial distribution and high beta-diversity of conodonts. As conodonts are currently believed to be a sister group to cyclostomes, our findings indicate that precise osmoregulation has likely been present in the common ancestor of both groups.

This complex spatial distribution patterns suggests a multitude of ecological roles played by conodonts in Palaeozoic ecosystems. Most biological information is derived from their mineralised teeth-like elements. Conodont elements evolved in parallel to gnathostome teeth and their function has been one of the largest palaeobiological enigmas for tens of years. Numerous lines of evidence indicate that conodont elements have adaptations to cutting and shearing of food. These adaptations include the structural organisation of their tissues at the level of individual crystals. Quantitative characterisation of crystallographic textures has recently become a prime tool in understanding material properties and structural adaptations in extinct organisms, but available analytical tools have so far failed in applications to phosphatic tissues. We have developed a new laboratory protocol to employ electron backscatter diffraction (EBSD) to quantify ultrastructural adaptation in conodonts. What is more, ultrastructural variation corresponds also to geochemical variability in conodonts, which, we speculate, might reflect the changes of their lifestyle during ontogeny.

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