SYSTEMATICS OF THE PARASPIRIFERIDAE TERMIER & TERMIER, 1949

The systematic position of the family Paraspiriferidae is highly controversial. After having been considered as a subfamily of the Delthyridoidae, its members are assigned to the subfamily Hysterolitinae in the revised Treatise on Invertebrate Paleontology. The lack of the notothyrial shelf, the presence of crural plates and lateral furrows, the elevated fold, and the tendency of bifurcation of ribs argues for rejection of paraspiriferid genera from the Hysterolitinae and for the validation of the family Paraspiriferidae. Genera of this family, Paraspirifer, Brachyspirifer, Torosospirifer, Bultynckia, and Gaspespirifer occur in North America, Europe, and North Africa. Questionable forms are reported also from Central Asia. Based on our cladistic analyses that show the relationships of paraspiriferid genera, we present a phylogenetic tree of this family. The origin of the Paraspiriferidae lies without doubt in Europe and arises from the group of Hysterohowellella out of which developed Brachyspirifer, a genus that occurs in North America, North Africa, and Europe. The step-by-step transition from Brachyspirifer to Paraspirifer can be observed in the Emsian strata of the German Rheinish Slate Mountains. Taxa of Parapspirifer show the widest abundance during the Middle Devonian and are also the youngest members of this family. In the Late Emsian, a radiation of genera within this family can be observed which confirms the increase of endemism at the end of the Early Devonian time. Due to the strong accretion of secondary shell material in the apical region and the pronounced development of gonoglyphs, we propose the elevation of Torosospirifer to genus level; its taxa occur in France and Portugal. Gaspespirifer occurs in eastern Canada and France whereas Bultynckia is restricted to the Spanish Cantabrian Mountains.