di Lugano (MCSN). Rupert Wild reviewed and redescribed all specimens known at the time via several large monographs in 1973/4 and 1980. In 2005, Silvio Renesto described a T. longobardicus specimen from Switzerland which preserved the impressions of skin and other soft tissue. Five new MSNM specimens of T. longobardicus were described by Stefania Nosotti in 2007, allowing for a more comprehensive view of the species' anatomy. A small but well-preserved skull and neck, specimen PIMUZ T 3901, was found in the slightly younger Meride Limestone at Monte San Giorgio. Wild (1980) gave it a new species, T. meridensis, based on a set of skull and vertebral traits proposed to differ from T. longobardicus. Later reinvestigations failed to confirm the validity of these differences, rendering T. meridensis a junior synonym of T. longobardicus. A 2019 revision of Tanystropheus found that T. longobardicus and T. antiquus were the only valid species in the genus. In 2020, large Tanystropheus specimens from Monte San Giorgio originally assigned to T. longobardicus were given a new species, T. hydroides. Polish and German species The first Tanystropheus specimens to be described were found in the mid-19th century. They included eight large vertebrae from the Upper Muschelkalk of Germany, and a partial skeleton from the Lower Keuper of Poland. These geological units occupy part of the Middle Triassic, from the latest Anisian to middle Ladinian stages. Though the fossils were initially given the name Macroscelosaurus by Count Georg Zu Münster, the publication containing this name is lost and its genus is considered a nomen oblitum. In 1855, Hermann von Meyer supplied the name Tanystropheus conspicuus, the type species of Tanystropheus, to the fossils. They were later regarded as Tanystropheus fossils undiagnostic relative to other species, rendering T. conspicuus a nomen dubium possibly synonymous with T. hydroides. In the late 1900s, Friedrich von Huene named several dubious Tanystropheus species from Germany and Poland. T. posthumus, from the Norian of Germany, was later reevaluated as an indeterminate theropod vertebra and a nomen dubium. Several more von Huene species, including "Procerosaurus cruralis", "Thecodontosaurus latespinatus", and "Thecodontosaurus primus", have been reconsidered as indeterminate material of Tanystropheus or other archosauromorphs. One of Von Huene's species appears to be valid: T. antiquus, from the Gogolin Formation of Poland, was based on cervical vertebrae which were proportionally shorter than those of other Tanystropheus species. Long considered destroyed in World War II, several T. antiquus