Un nouveau ptéraspidiforme (Vertebrata, Heterostraci) du Dévonien inférieur du Spitsberg : nouvelles données paléo-ontogéniques

Woodfjordaspis felixi n. gen., n. sp. (Vertebrata, Heterostraci, Pteraspidiformes) is found in a locality of the lowermost Wood Bay Formation (Lower Devonian, Spitsbergen). The available material remains rare and incomplete. The morphological analysis points out the development of the triangular orbital plates and the lack of dorsal spine. This new taxon shows a peculiar morphology of its ventral disc. The successive concentric stages are interpreted as an evidence of growth, which leads to propose a new palaeo-ontogeny model supported by the occurrence of juvenile specimens in the locality.