Cambrian and Early Ordovician Trilobite Taxonomy and Biostratigraphy, Bonaparte Basin, Western Australia

A total of 38 trilobite taxa are described from 186 collections made in 1963 and 1969. The material is often exceedingly poorly preserved in friable quartz sandstone, glauconitic sandstone or glauconite, which have been deeply effected by tropical weathering. Much of it is either compared to the nearest similar species, or is left under open nomenclature. The complete fauna is classified amongst existing genera. However, five new species are recognised: Dictyella conica, Kaolishania clarkensis, Liostracina kaulbacki, Prosaukia? pentecosti and Taenicephalus? travesi. The described trilobites permit a revision of the informal biostratigraphy suggested by A.A. pik in the mid-sixties. Accordingly, pik's Faunal Units I and II must now be combined into a single unit. No positive evidence has been found for the existence of Faunal Unit IV, and Faunal Unit VI is younger than previously considered, falling stratigraphically within the early part of Faunal Unit VIII. Previous divisions of Faunal Unit X cannot be substantiated, and the elements used to diagnose Faunal Unit XI are older, also belonging to Unit X. Three assemblages can be recognised in Faunal Unit XII. Compared to central Australia, faunas of Ordian (mostly Early Cambrian), late Mindyallan (Glyptagnostus stolidotus Zone; latest Middle Cambrian), mid and late Iverian, Payntonian, late Datsonian (Furongian) and Warendan (Early Ordovician) age are represented. The post-Ordian to pre-late Mindyallan Middle Cambrian, and the Late Cambrian Idamean and early Iverian Stages are definitely unrepresented by age diagnostic faunas to date, and the late Payntonian-early Datsonian is represented by an hiatus.