-Zircons from a bentonite near the base of the Purley Shale Formation in the Nuneaton area, Warwickshire, yield a 206 Pb/ 238 U age of 517.22 ± 0.31 Ma. Based on the fauna of small shelly fossils and the brachiopod Micromitra phillipsii in the underlying Home Farm Member of the Hartshill Sandstone Formation, trilobite fragments that are questionably referred to Callavia from the basal Purley Shale Formation, and the presence of trilobites diagnostic of the sabulosa Biozone 66 m above the base of the Purley Shale Formation, the bentonite likely dates an horizon within Cambrian Stage 3, at about the level of the Fallotaspis or basal Callavia Biozone. This is consistent with bentonite ages from other localities in southern Britain, which constrain the age of the lower and uppermost parts of Cambrian Stage 3. The new date provides additional chronological control on the earliest occurrence of trilobites in the Midland Microcraton, a date for the marine transgression at the base of the Purley Shale Formation, and is the first radiometric age from the Cambrian succession of Warwickshire.

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The history of the Iapetus Ocean in the Early Palaeozoic is well‐established, and faunal distribution has contributed significantly to the development of this knowledge; however, lingulate brachiopods have traditionally been considered to be of little utility in assessing palaeobiogeography. The distribution of lingulate brachiopods across the Iapetus region is analysed using a number of similarity indices and other statistical measures. This analysis shows a clear palaeobiogeographic signal where lingulate faunas are sufficiently diverse, reflecting the history of the Iapetus ocean and the relative separation of Laurentia and Baltica through the Cambrian and Ordovician. Lingulate faunas on Avalonia are, however, low in diversity and show relatively high endemism; this renders them of little use in assessing the separation of Avalonia from other areas. Evidence of earlier increases in faunal similarity in lingulate faunas between continents, compared to other fossil groups, provides confirmatory evidence that Palaeozoic lingulates had long‐lived planktotrophic larvae.

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