Portlandemys gracilis n. sp., a New Coastal Marine Turtle from the Late Jurassic of Porrentruy (Switzerland) and a Reconsideration of Plesiochelyid Cranial Anatomy

摘要: Background Several groups of stem cryptodires became adapted to coastal marine environments as early the Late Jurassic, 40 million years before Pan-Chelonioidea. The Plesiochelyidae are a major component this first radiation crown-group turtles into habitats. They abundant in many European localities, but their systematics is still greatly confused. Only three species represented by cranial material: Plesiochelys etalloni, planiceps, and Portlandemys mcdowelli. Methodology/Principal Findings In present study, we describe cranium mandible from Kimmeridgian Porrentruy (Switzerland), which refer new species, gracilis n. sp. This taxon differs mcdowelli several aspects mandible, notably being generally more gracile, two share narrow skull, acute angle between labial ridges on unique configuration anterodorsal part basicranium. anatomy plesiochelyid discussed details based primarily these specimens material etalloni Solothurn, Switzerland. Conclusions/Significance characters (e.g., contribution parietal foramen nervi trigemini, dorsum sellae sella turcica, presence an infolding ridge posterior surface quadrate) appear potential candidates help elucidate relationships. Some included previously published phylogenetic dataset stabilize relationships closely related taxa. For time, our results suggest that plesiochelyids, 'Thalassemys' moseri, Solnhofia parsonsi (representing Eurysternidae) form clade at base Eucryptodira.