Solemys (Chelonii, Solemydidae) remains from the Maastrichtian of Pyrenees: evidence for a semi-aquatic lifestyle

We report on a turtle from the Mina Esquirol site (Vallcebre basin), a new locality of early Maastrichtian age in the south-eastern Pyrenees. Fossils were located in the basal Tremp Formation, which was deposited in a littoral marsh. The material consists of a cast of a carapace including peripheral fragments and partial neural plates. The carapace exhibits a vermiculate ornamentation that is characteristic of genus Solemys and a histological bone structure similar to that of terrestrial taxa. However, taphonomic data indicates little transport and a short biostratinomic history, whereas palaeontological and sedimentological context indicates that the specimen was preserved in a shallow brackish water environment. Based on this taphonomic and sedimentological evidence, we suggest that at least some species of genus Solemys had a lifestyle similar to extant fresh or brackish water turtles (terrapins) and that the histological evidence alone for a terrestrial lifestyle is misleading.