A marine vertebrate fauna from the Late Triassic of Somerset, and a review of British placodonts

摘要: Abstract The British Rhaetian (latest Triassic) is famous for its bone beds containing abundant remains of fishes and reptiles. Most are assumed to have been similar in faunal composition, representing long-distance mixing transported remains, deposition some distance from shore. In the Mendip Hills southwest England, lie unconformably on Carboniferous Limestone, where marine sediments Transgression lapped onto shorelines palaeo-islands. fauna Marston Road site, near Holwell, Shepton Mallet, Somerset, shows a remarkable association coastal terrestrial reptile mixed with usual teeth scales sharks bony fishes. We report unequivocal fossils small lepidosaur, probably sphenodontian, wash-in, as well reptiles, possible thalattosaur Pachystropheus placodonts. Sphenodontian Late Triassic red bed fissure fills nearby, site provides palaeoecological/topographic link between deposits, hinting also that development vertebrate-bearing fissures may coeval transgression.