Neltneriidae and Holmiidae (Trilobita) from Morocco and the problem of Early Cambrian intercontinental correlation

Previously undescribed Holmiidae from theSectigenaZone of Morocco indicate correlation of this zone with other zones bearing Holmiidae on Baltica, Avalonia, Siberia, and Laurentia. The occurrence of the youngest Antatlasiinae in theSectigenaZone and the oldest Protoleninae in the overlyingHupeolenusZone suggests correlations of theSectigenaZone with upper Atdabanian beds bearing the youngest Antatlasiinae and theHupeolenusZone with Botomian beds bearing the oldest Protoleninae in Siberia. The occurrence, in the overlyingHupeolenusandCephalopygeZones, ofParadoxidess.l. in association with the olenelloidCambropallasand with trilobites characteristic of the Lower Cambrian “Protolenus” Zone of Avalonia calls into question the major criteria for recognition of strata of Early and Middle Cambrian age. New taxa includelyouella contractan. gen. and sp. of the Holmiidae andBondonella sdzuyin. sp. of the Neltneriidae. The known species ofNeltneria, N. jacquetiandN. termieri, are revised.