Largest shell of a basal eucryptodiran turtle reveals Late Jurassic Thalassemys hugii in the British record

A British turtle specimen with the largest shell of a basal eucryptodiran turtle recognized globally is presented and analyzed. It belongs to Thalassemys hugii, the type species of both Thalassemys and Thalassemydidae, a poorly-known European Late Jurassic clade. T. hugii is recognized outside Central Europe for the first time. Therefore, this finding offers new data on its geographical distribution and on its intraspecific variability.