Dr. Bertrand Lefebvre, Université de Lyon

My research :

I am investigating all aspects (e.g., disparity, diversity, phylogeny, paleoecology, paleobiogeography) of the early diversification of a major clade of marine metazoans in Early Palaeozoic times: the phylum Echinodermata. My research focuses mostly on stylophorans (Cornuta and Mitrata), a class of bizarre-looking, flattened, and asymmetrical echinoderms, characterized by the possession of a single feeding arm. Their puzzling morphology is frequently compared with that of hemichordates, chordates, and/or various primitive deuterostomes (e.g., vetulicolians). As a consequence, the phylogenetic position of stylophorans remains a hotly controversial issue, with deep insights on deuterostome phylogeny. However, the « flatfish » design of stylophorans is probably derived, and results from the adoption of an epibenthic, unattached mode of life, very likely correlated to the onset of the « Cambrian Substrate Revolution » (« snowshoe morphology »). Stylophorans are known from the Middle Cambrian to the Pennsylvanian. In the Late Cambrian-Early Ordovician time interval, they were particularly diverse and widespread, and then constituted a significant component of echinoderm assemblages.

Working with the CMC Collection

The Cincinnati Museum Center possesses one of the largest collection of stylophorans in North America. The bulk of this material comprises a diverse and representative assemblage of Ordovician (Anatifopsis, Ateleocystites, Enoploura) and Devonian (Anomalocystites) mitrates from both the USA and Canada. However, the collections of invertebrate fossils of the CMC also possess an unexpectingly rich material of Cambrian (Ceratocystis) and Ordovician (Anatifopsis, Balanocystites, Lagynocystis, Mitrocystella, Mitrocystites, Promitrocystites, Thoralicystis) stylophorans from Bohemia (Czech Republic), as well as from the Silurian of England (Placocystites). From an European perspective, it was particularly exciting to examine North American stylophorans, which are preserved as 3D calcite specimens. In Europe and North Africa, the preservation of stylophorans is generally mouldic, and we have to produce latex casts to know what they were actually looking like. My stay in the collections of the CMC was very fruitful, as I could observe directly for the first time most of the « well-known » stylophorans from North America (including several type and figured specimens). The drawer with « unidentified carpoids » was particularly exciting, as it contained not only the third known specimen of the rare Bohemian cornute Thoralicystis bouceki, but also what is probably the first specimen of allanicytidiine mitrate ever reported in the Devonian of North America. As a consequence, my visit in the collections of the CMC will certainly result in at least one or two publications.

Monday, October 13, 2008