Vendredi 22 novembre - Amphi Mérieux, ENS de Lyon
Lyon (France)
Phylogeny of gogiid blastozoans: insights into the Cambrian diversification of echinoderms
Christophe Dupichaud  1@  , Elise Nardin, Rich Mooi, Martina Nohejlová, Lefebvre Bertrand  2@  
1 : Laboratoire de Géologie de Lyon
Université Claude Bernard-Lyon I - UCBL (FRANCE)
2 : Laboratoire de Géologie de Lyon, CNRS, UMR 5276
Université Claude Bernard - Lyon I

 

The phylum Echinodermata has been known in the fossil record since the Cambrian Series 2. Among its earliest representatives, eocrinoid blastozoans are the oldest bearing free feeding appendages (brachioles). Most Cambrian eocrinoids are grouped within the order Gogiida Broadhead, 1982. They exhibit a wide range of morphological disparity and a large palaeobiogeographic distribution. Historically, gogiids have been extensively described in Laurentia (modern North America), and they have been attributed to many species, all assigned to the same genus: Gogia. Over the years, gogiids have also been discovered in other palaeogeographic areas (high-latitude Gondwana, South China), and often attributed to new monospecific genera. In the last twenty years, ontogenetic series of several gogiids were documented, based on abundant and well-preserved material from China and the Czech Republic. Such ontogenetic series question the possibility that some of the numerous gogiids from North America may correspond to different ontogenetic stages of a more limited number of taxa. Hence, this study aims to 1) review the species of the genus Gogia and their possible ontogenetic relationships, 2) explore affinities between gogiids from various palaeogeographic areas, and 3) complete the first phylogenetic analysis of this order.


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