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Sixteen different Lower Carboniferous (Tournaisian Courceyan to Chadian age, Mississippian) chondrichthyan teeth types have been extracted from Triassic erosional/aeolian fills in shallow karst systems found in the limestone quarry at Cromhall, Gloucestershire, England. These Carboniferous teeth have been found within a much larger assemblage of disarticulated bones and teeth belonging to small late Triassic terrestrial reptiles, for which Cromhall quarry is famous. The Carboniferous teeth are derived fossils, released during subaerial dissolution of the surrounding limestones. Owing to low specimen numbers and uncertainty of intraspecific character, 10 types of teeth are left in open nomenclature, although it is likely they represent new taxa. They belong to Jalodus, Ctenacanthiformes, Protacrodus, Orodus, Chomatodus, Petalodontidae, Euchondrocephali?, Helodus and Psephodus. A new genus and species, Cromhallia parvunda, of indeterminate phylogenetic relationships, is also erected. The assemblage includes also an identified suite comprising Thrinacodus ferox, Bransonella cf. nebraskensis and Stethacanthus cf. altonensis. The identification of all fish teeth found in the Cromhall assemblages as derived fossils from the Carboniferous removes any ambiguity regarding the fully terrestrial nature of the late Triassic fauna preserved in the residue-bearing karst systems.

The partly articulated specimen of the Palaeozoic (Early Carboniferous) chondrichthyan ‘Cladodus’neilsoni Traquair from East Kilbride has been known since the late nineteenth century. As such, ‘C.’neilsoni Traquair has been cited in numerous publications, but it has become increasingly clear that its anatomy and systematic affinities are obscure. This comprehensive redescription of ‘C.’neilsoni reveals new details of the neurocranium (including presence of an otico-occipital fissure), dentition, visceral arches (clarifying the condition of the basibranchial pattern plus elongate copula), and pectoral fin. These data refute previously suggested synonymies, such as between ‘C’neilsoni and the contemporaneous Bearsden Stethacanthus. Attribution of ‘C.’neilsoni to the taxonomically unsupportable genus ‘Cladodus’ is rejected, and the species is redesignated as Gutturensisneilsoni gen. nov. Preliminary cladistic analysis places Gutturensisneilsoni within a polytomy including Stethacanthus, the symmoriid Cobelodus, and the root of a monophyletic group of neoselachian-like genera. ‘ Cladodont’ as a diagnostic term for early chondrichthyan teeth is found to be insufficiently precise, referring to an ill-defined grade of tooth morphologies present in a wide variety of Palaeozoic genera.