Tanystropheus (~ 'long' + 'hinged') is an extinct genus of archosauromorph reptile from the Middle and Late Triassic epochs. It is recognisable by its extremely elongated neck, which measured long—longer than its body and tail combined. The neck was composed of 12–13 extremely elongated vertebrae. With its very long but relatively stiff neck, Tanystropheus has been often proposed and reconstructed as an aquatic or semi-aquatic reptile, an interpretation supported by the fact that the creature is most commonly found in semi-aquatic fossil sites where known terrestrial reptile remains are scarce. Complete skeletons are common in the Besano Formation at Monte San Giorgio in Italy and Switzerland; other fossils have been found throughout Europe, North America, and Asia, dating from the Middle Triassic (Anisian and Ladinian stages) to the early part of the Late Triassic (earliest Carnian stage). History and species Monte San Giorgio species 19th century excavations at Monte San Giorgio, a UNESCO world heritage site on the Italy-Switzerland border, revealed a fragmentary fossil of an animal with three-cusped (tricuspid) teeth and elongated bones. Monte San Giorgio preserves the Besano Formation (also known as the Grenzbitumenzone), a late Anisian-early Ladinian lagerstätte recognised for its spectacular fossils. In 1886, Francesco Bassani interpreted the unusual tricuspid fossil as a pterosaur, which he named Tribelesodon longobardicus. The holotype specimen of Tribelesodon longobardicus was stored in the Museo Civico di Storia Naturale di Milano (Natural History Museum of Milan), and was destroyed by allied bombing of Milan in World War II. Excavations by University of Zürich paleontologist Bernhard Peyer in the late 1920s and 1930s revealed many more complete fossils of the species from Monte San Giorgio. Peyer's discoveries allowed Tribelesodon longobardicus to be recognised as a non-flying reptile, more than 40 years after its original description. Its supposed elongated finger bones were recognized as neck vertebrae, which compared favorably with those previously described as Tanystropheus from Germany and Poland. Thus, Tribelesodon longobardicus was renamed to Tanystropheus longobardicus and its anatomy was revised into a long-necked, non-pterosaur reptile. Specimen PIMUZ T 2791, which was discovered in 1929, has been designated as the neotype of the species. Well-preserved T. longobardicus fossils continue to be recovered from Monte San Giorgio up to the present day. Fossils from the mountain are primarily stored at the rebuilt Museo Civico di Storia Naturale di Milano (MSNM), the Paleontological Museum of Zürich (PIMUZ), and the Museo Cantonale di Scienze Naturali