Helochelydridae

The skull, shell and osteoderms of helochelydrids are covered in small, cylindrical protuberances, which are a distinctive characteristic of the group. They are thought to be terrestrial, based on the presence of limb osteoderms (granicones) and bone histology. Their skull morphology is dissimilar to that of extant tortoises, suggesting an omnivorous habit similar to that of box turtles. == Taxonomy ==

Helochelydridae includes all turtles that are more closely related to Helochelydra than Sichuanchelys, Meiolania, or extant turtles. Although referred to as Solemydidae in recent literature on extinct turtles, Helochelydridae has priority over Solemydidae. They are placed as part of the clade Perichelydia. Some recent studies have recovered them as paracryptodires, though other studies have found them to be more basal than paracryptodires. Position of helochelydrids according to Tong et. al. 2023: }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }}}} == Genera ==

• Aragochersis Escucha Formation, Spain, Early Cretaceous (Albian) • Helochelydra Wessex Formation, England, Early Cretaceous (Barremian) • "Helochelydra" anglica (Lydekker, 1889) Purbeck Group, United Kingdom, (Berriasian) • "Helochelydra" bakewelli Mantell, 1833 Tunbridge Wells Sandstone, England, (Valanginian) • Helochelys Grünsandstein Formation, Germany, Late Cretaceous (Cenomanian), Cambridge Greensand, England, Albian-Cenomanian, France, Spain, Cenomanian • Trachydermochelys phlyctaenus Seeley 1869 (revised Joyce, 2022), Cambridge Greensand, England, Albian-Cenomanian • Naomichelys Cretaceous (Aptian-Campanian) North America == References ==