A juvenile eurysternid turtle (Testudines: Eurysternidae) from the upper Kimmeridgian (Upper Jurassic) of Nusplingen (SW Germany)

A juvenile turtle from the upper Kimmeridgian (Upper Jurassic) of Nusplingen is identified as an eurysternid turtle. It differs in plastral morphology from a juvenile eurysternid turtle from the latest Kimmerdigian of Kelheim described in the 19th century, which represents a comparably early developmental stage. Both juveniles have primordial ribs not yet transformed into costals and lack all other carapacial elements whereas the plastral elements are well developed. The new specimen from Nusplingen has a more robust plastron type when compared to the very gracile, bow- or arc-shaped plastron type of the formerly described juvenile. Both plastron types are also represented by yet undescribed additional juvenile, medium-sized and/or larger eurysternid specimens. The juvenile specimens thus likely document the presence of two morphologically very similar eurysternid taxa in the Upper Jurassic of southern Germany. Both plastron types are different from those described for Idiochelys and Solnhofia but may resemble plastron morphology of Eurysternum, which is, however, only incompletely known.