The comparative osteology of n. sp., a new coastal marine turtle from the Late Jurassic of Porrentruy (Switzerland).

BACKGROUND

During the Late Jurassic, several groups of eucryptodiran turtles inhabited the shallow epicontinental seas of Western Europe. Plesiochelyidae are an important part of this first radiation of crown-group turtles into coastal marine ecosystems. Fossils of Plesiochelyidae occur in many European localities, and are especially abundant in the Kimmeridgian layers of the Swiss Jura Mountains (Solothurn and Porrentruy). In the mid-19th century, the quarries of Solothurn (NW Switzerland) already provided a large amount of fossil turtles, most notably , the best-known plesiochelyid species. Recent excavations in the Porrentruy area (NW Switzerland) revealed new fossils of , including numerous well-preserved shells with associated cranial and postcranial material.

METHODS/RESULTS: Out of 80 shells referred to , 41 are assigned to a new species, n. sp., including a skull-shell association. We furthermore refer 15 shells to , and 24 shells to sp. Anatomical comparisons show that can clearly be differentiated from by cranial features. The shell anatomy and the appendicular skeleton of and are very similar. However, a statistical analysis demonstrates that the thickness of neural bones allows to separate the two species based on incomplete material. This study furthermore illustrates the extent of intraspecific variation in the shell anatomy of and .