''Achelonia'' is an extinct genus of marine

thalassochelydia Thalassochelydia is a clade of extinct marine turtles from the Late Jurassic and earliest Cretaceous of Europe and South America. The group is defined as including ''Eurysternum'', ''Plesiochelys'' and ''Thalassemys'' to the exclusion of ''Pelome ...

n turtle. Its

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

is ''Achelonia formosa''. Fossils are known from the Upper Jurassic (late

Kimmeridgian In the geologic timescale, the Kimmeridgian is an age in the Late Jurassic Epoch and a stage in the Upper Jurassic Series. It spans the time between 157.3 ± 1.0 Ma and 152.1 ± 0.9 Ma (million years ago). The Kimmeridgian follows the Oxfordian ...

) of Wattendorf, Germany, Cerin, France, and England. Material from England was originally considered to belong to the separate genus ''Enaliochelys'' and species ''Enaliochelys chelonia'', named by

Harry Govier Seeley Harry Govier Seeley (18 February 1839 – 8 January 1909) was a British paleontologist. Early life Seeley was born in London on 18 February 1839, the second son of Richard Hovill Seeley, a goldsmith, and his second wife Mary Govier. When his fat ...

in 1869 for a partial disarticulated skeleton from the early

of the

Kimmeridge Clay The Kimmeridge Clay is a sedimentary deposit of fossiliferous marine clay which is of Late Jurassic to lowermost Cretaceous age and occurs in southern and eastern England and in the North Sea. This rock formation is the major source rock for North ...

Cambridgeshire Cambridgeshire (abbreviated Cambs.) is a Counties of England, county in the East of England, bordering Lincolnshire to the north, Norfolk to the north-east, Suffolk to the east, Essex and Hertfordshire to the south, and Bedfordshire and North ...

. The synonymy was recognised in 2020.

References

Thalassochelydia Prehistoric turtle genera Kimmeridgian genera Late Jurassic turtles Late Jurassic reptiles of Europe Jurassic Germany Fossils of Germany Fossil taxa described in 1860 Taxa named by Christian Erich Hermann von Meyer {{Paleo-turtle-stub