title: Seeleyosaurus
text: # Seeleyosaurus
  
  Seeleyosaurus is an extinct genus of plesiosaur that was initially placed within the genus Plesiosaurus in 1895 and was given its own genus in 1940. Two species were known: the type, S. guilelmiimperatoris, and the now obsolete species S. holzmadensis, 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. 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. A second specimen (SMNS 12039), preserved in 3D, is the holotype of S. holzmadensis.
  
  ## Classification
  
  The following cladogram follows an analysis by Ketchum & Benson, 2011.
  
  ## Gallery
  
  * Restoration
  * Holotype of S. guilelmiimperatoris in 1895
  * Seeleyosaurus (left) and Thaumatosaurus, now Meyerasaurus (right) as depicted in Water reptiles of the past and present (1914)
  