Seeleyosaurus_guilelmiimperatoris
Seeleyosaurus
Genus of reptiles (fossil)
Seeleyosaurus is an extinct genus of plesiosaur that was initially placed within the genus Plesiosaurus in 1895[1] and was given its own genus in 1940.[2] Two species were known: the type, S. guilelmiimperatoris, and the now obsolete species S. holzmadensis,[2] which has since been absorbed into S. guilelmiimperatoris. It was a relatively small plesiosaur, measuring 2.9–3.6 m (9.5–11.8 ft) long.[3][4] The holotype is MB.R.1992, a large almost complete skeleton from the Upper Lias (Toarcian) Lias Group Formations of Württemberg, Germany. There seems to be the impression of a rhomboidal flap of skin in a vertical plane; if so, many plesiosaurs may have been equipped in this way.[5] A second specimen (SMNS 12039), preserved in 3D, is the holotype of S. holzmadensis.[2]