Mixosaurus cornalianus is an ichthyosaur that lived in the Middle Triassic 244-240 million years ago. Many fossils of this genus have been found in North America, Asia and Europe while M. cornalianus was found for the first time in the Besano field, in Italy. The skull was very large compared to the body, and was equipped with a sagittal crest associated with the superior temporal window that had expanded, allowing the insertion of maxillary muscles giving the species a very powerful bite. The neck was short, as for most of the more derived ichthyosaurs while the presence of a dorsal fin was uncertain until a few years ago. In fact, in 2020, the discovery of a dorsal fin of a Mixosaurus cornalianus discovered in Besani, in the province of Varese, was published. This discovery anticipates the appearance of this feature by nearly 50 million years, indicating that these marine reptiles developed adaptations to "fast and efficient swimming" well before the more derivative species of the Jurassic. The skin was smooth, without scales and the fibers of the dorsal fin gave it a dynamic flexibility, in such a way as to give the reptile stability and swimming efficiency, especially for catching fast prey such as squid. It also sets a further record: it is the oldest amniote known to date to have developed a dorsal fin.
 
 SILVIO RENESTO, CRISTIANO DAL SASSO, FABIO FOGLIAZZA, and CINZIA RAGNI. 2020. New findings reveal that the Middle Triassic ichthyosaur Mixosaurus cornalianus is the oldest amniote with a dorsal fin
 
 Maisch, MW, Matzke, AT & Brinkmann, W. The otic capsule of the Middle Triassic ichthyosaur  Mixosaurus  from Monte San Giorgio (Switzerland): New evidence on the braincase structure of basal ichthyosaurs.  Eclogae geol. Helv.  99,  205-210 (2006). https://doi.org/10.1007/s00015-006-1189-6
 
 Maisch, Michael W .; Matzke, Andreas T. 1997: Observations on Triassic ichthyosaurs. Part I: Structure of the palate and mode of tooth implantation in Mixosaurus cornalianus (Bassani, 1886).