The first complete skeleton of Solnhofia parsonsi (Cryptodira, Eurysternidae) from the Upper Jurassic of Germany and its taxonomic implications

Abstract

A complete skeleton of Solnhofia parsonsi (Cryptodira, Eurysternidae) from the Kimmeridgian/Tithonian boundary of Schamhaupten, Germany provides the first complete understanding of the postcranial morphology of this genus. The here newly described postcranial characters are important in distinguishing Solnhofia from shell-based genera and thus help in resolving part of the parataxonomic conflict between shell-based and cranium-based turtle genera. This disparity originated during the last 150 years due to the history of fossil finds, preparation, and changing interests of researchers. Synonymies of Solnhofia with such turtle genera as Eurysternum, Idiochelys, Plesiochelys, Thalassemys, and Euryaspis can now be refuted. Similarities with Hydropelta are apparent, but not considered sufficient to support a synonymy. Newly observed or confirmed characters include the relatively large head (40 percent of the carapace length), the pentagonal carapace, the unique arrangement of bones and fontanelles in the pygal region, and the absence of mesoplastra, epiplastra, and an entoplastron.The carcass of the new specimen was embedded in finely laminated limestones and shows little sign of disintegration or scavenging, suggesting hostile bottom conditions with very low water energy during deposition. This taphonomy agrees with recent published models for the origin of the lithographic limestones of southern Germany. Tooth marks along the posterior margin of the carapace are evidence of predation by a broad-nosed crocodilian. This is the first clear example for this type of predatorial interaction from the Upper Jurassic of Germany.