Eosphargis

Eosphargis is an extinct genus of sea turtles from the late Paleocene and early Eocene of western Europe and eastern North America. It is a member of the family Dermochelyidae, which also includes the modern leatherback sea turtle, of which it is the earliest known definitive member.

Taxonomy

The genus Eosphargis was first described by British paleontologist Richard Lydekker in 1889. It contains three known species:'
The following species are known:
†E. breineri Nielsen, 1959 - Early Eocene of Denmark
†E. gigas - Early Eocene of England, potentially Maryland, US
†E. insularis - Late Paleocene of New Jersey, US and Virginia, US
It is possible that E. insularis is conspecific with one of the two other known species, as it is known from only fragmentary material. It was excluded from a 2025 taxonomic review for this reason.' E. breineri is known from the Fur Formation lagerstatte of Denmark, and is thus the species with the best-preserved remains.
In 1964, an alleged record of a scapula from an early archaeocete whale from the London Clay was described as †Anglocetus beatsoni Tarlo, 1964. This would have been one of the earliest known whales, and one of the only known from the Eocene of Europe. However, a later analysis found this bone to likely belong to an individual of E. gigas.