Opisthosomal fusion and phylogeny of Palaeozoic Xiphosura

Abstract

Fusion of opisthosomal tergites to form a thoracetron has previously been considered a characteristic of the xiphosuran superfamilies Euproopoidea Eller, 1938, and Limuloidea Zittel, 1885. Evidence is presented here that fusion also occurs in Bellinuroidea Zittel & Eastman, 1913. Results of a cladistic analysis of Palaeozoic xiphosuran genera indicate that Synziphosurina Packard, 1886, is a paraphyletic assemblage of stem‐group Xiphosura. Superfamily Paleolimulidae superfam. nov. is erected for families Paleolimulidae Raymond, 1944, and Moravuridae P&íbyl, 1967.