THE OLDEST VERTEBRATES OF THE GRAND-DUCHY OF LUXEMBOURG - BRACHYTHORACID ARTHRODIRES (PLACODERMI, EARLY DEVONIAN)

Two dermal plates of the thoracic shield of brachythoracid arthrodires have been discovered in Emsian localities of the Grand-Duchy of Luxem bourg (GDL). They represent the first confirmed discovery of vertebrat es in the Lower Devonian of the GDL, and thus become the oldest verteb rates of this country. They are also interesting by the fact that the occurrence of Brachythoraci in the Devonian of the Ardenne Allochthon has been, until now, very rare. The features of one of both plates fit rather well with the shape of the homologous plate of the Coccosteida e; this family is usually unreported in Lower Devonian rocks. ((C) Aca demie des sciences / Elsevier, Paris.)