Evaluation of the Validity of the Spanish Eocene Pleurodiran Turtle ‘Duerochelys arribasi’: The Youngest Freshwater Member of Erymnochelyinae (Podocnemididae) in Europe

The validity of the youngest representative of Neochelys described to date, representing the last European freshwater member of Erymnochelyinae, has been considered doubtful. A revision of the previously documented specimens of this Spanish Bartonian or Priabonian (MP 16 or MP 17, middle or late Eocene) species is performed here, along with the analysis of additional unpublished remains from the same geological formation. The principal character originally used to diagnose the species (i.e., paired gular scutes) is refuted here, and interpreted instead as an anomalous variation that is also found in other representatives of the genus. However, Neochelys arribasi is supported as a valid species based on other morphological features. We recognize here an increase in size for the representatives of Neochelys from the Duero Basin over time, which are also the youngest known species of Neochelys.