Microvertebrates from the basal Rhaetian Bone Bed (Late Triassic) at Lavernock, South Wales

The cliff and foreshore sections at Lavernock, South Wales form the type section of the Penarth Group, representing the Rhaetian stage in the UK, the latest Triassic. The Rhaetian bonebeds here have been famous for over 150 years for their vertebrate fossils. Here, we show that, unusually, the Lavernock basal Westbury Formation bonebed is dominated by osteichthyan teeth, with sharks such as Lissodus relatively rare. The rounded teeth of the durophagous bony fish Sargodon are abundant, with teeth of Severnichthys next in abundance, and Gyrolepis the rarest, quite unlike most other Rhaetian bone beds. Also, small elements such as shark denticles have not been found, whilst larger bones of marine reptiles (ichthyosaurs, plesiosaurs) and dinosaurs do occur. The dinosaur bones are unusual, and Lavernock may have yielded more such bones than any other British Rhaetian bone bed. These terrestrial elements suggest that the lower bone bed accumulated close to shore, but underwent considerable transport, with clasts perhaps moving back and forwards, to explain the abrasion of specimens, the larger elements and absence of smaller specimens. Dinosaurs are more widely documented in the Late Triassic of the Penarth area, around Lavernock, than anywhere else in the UK.