Through a glass darkly: taxonomy, phylogeny, and biostratigraphy of the Olenellina

The Olenellina is an exclusively Early Cambrian trilobite suborder that dominates the later Early Cambrian trilobite faunas of Laurentia and constitutes a lesser component of the trilobite faunas of Siberia, Baltica, Avalonia, and the western sector of Gondwana/peri-Gondwana (Morocco, Spain, and eastern (;ermany). The classification of the Olenellina presented here will appear in the revised edition on Trilobita of the Treatise on Invertebrate Paleontology. Two superfamilies, 7 families, 10 subfamilies, 45 genera, and 5 subgenera are distinguished primarily on characters of the cephalon. Major revisions from previous usage primarily involve the Laurentian Olenellidae. New taxa in this family include Bristoliinae, Gabriellinac, Laudoniinae, A reuotenellus, Bolbolenellus, Nephmlenelbts, Olenelhis (Angustolenellus), and Oletzellus (Mesolenelhis). One new taxon, Paranevadella, is added to the Judomiidae. The previously synonymized genera Meson ads and Paedeumias are revived as subgenera of Olenellus. Intercontinental correlation of Lower Cambrian strata is hampered by high endemism of genera and species, especially among the Olenellina. Biostratigraphic and biogeographic analysis of the Olenellina suggests increasing geographic isolation of Laurentia during Early Cambrian time and that Laurentian Olenellidae are mostly younger than the Olenellina of the other Cambrian continents. Morphologic and stratigraphie considerations suggest derivation of the Olenellidae from some element of the Hohniidae and the Holmiidae from some element of the Archaeaspididae.