Data from: Biostratigraphy and geometric morphometrics of conchostracans (Crustacea, Branchiopoda) from the Late Triassic fissure deposits of Cromhall Quarry, UK

The enigmatic fissure deposits of south-eastern England and southern Wales
are famous for their unique assemblage of Late Triassic vertebrates,
although their age is contentious. While recent studies of palynomorphs
have dated some as Rhaetian, their conchostracan (Crustacea, Branchiopoda)
assemblages have not been described in detail nor used in biostratigraphy.
We find that species determination of British Late Triassic conchostracans
requires detailed observations of size, shape and ornamentation. We
provide evidence that although Euestheria brodieana is invariably smaller
than E. minuta, with some slight differences in carapace ornamentation,
the traditional view that they are very similar is upheld. The use of
conchostracans as a biostratigraphical tool is here tested by application
to the British Triassic fissures at Cromhall quarry where the usual
stratigraphical evidence provided by superposition is absent. We find no
distinction between conchostracans from bedded Rhaetian deposits of the UK
and specimens collected from the fissure deposits of Cromhall Quarry,
Gloucestershire, supporting a late Rhaetian age for these deposits.