R. cramptoni In July 1848, a fossil of a large plesiosaur was unearthed in an
alum quarry at
Kettleness, near Whitby, in Yorkshire, England. It was collected from the
A. bifrons ammonite zone of the
Whitby Mudstone Formation, dating to the early
Toarcian age, about 183 to 180 million years ago. The complete
skeleton which preserved the
skull,
NMING F8785, was kept for five years at
Mulgrave Castle, which was then owned by the
Marquess of Normanby. In 1853, the Marquess introduced the interesting finding to the eminent Irish surgeon and anatomist,
Sir Philip Crampton. The same year, Crampton transferred the fossil to
Dublin to be displayed as a centrepiece at the 1853
British Association annual meeting. The
Zoological Society of Ireland built a specially constructed building to house the large reptile. After a decade, still remaining undescribed, the specimen moved in the
Royal Dublin Society museum and was officially described by
Alexander Carte and
W. H. Bailey as a new species of
Plesiosaurus. Carte and Bailey named the species
Plesiosaurus cramptoni after the Irish scientist, Sir Philip Crampton. In 1874, the British geologist
Harry Govier Seeley, based on this finding, which is now known as the
type genus of the family
Rhomaleosauridae, recognized and erected a new genus establishing
Rhomaleosaurus. Only in 2006 the
skull of this specimen was finally prepared which enabled a restudy of this genus. Casts of the holotype specimen are on display at the Natural History Museum, London (NHMUK PV R 34) and Bath Royal Literary and Scientific Institution.
R. propinquus R. propinquus is known from the
holotype WM 852.S, articulated almost complete
skeleton which preserved the
skull, exposed in
dorsal view. It was collected from the
A. serpentines ammonoid zone, of the
Whitby Mudstone Formation, Yorkshire, England, dating to the middle Toarcian stage, about 180-177
million years ago.
R. propinquus was first named by Tate and Blake in
1876 as a new species of
Plesiosaurus. Watson (1910) redescribed it as a species of
Rhomaleosaurus. Adam S. Smith (2007), in his thesis on the anatomy and classification of the family
Rhomaleosauridae, suggested that
R. propinquus, is a junior synonym of
Rhomaleosaurus zetlandicus. and its skull was described in detail by Michael Alan Taylor in 1992. Later the taxon was revised by Cruickshank (1996) as a senior synonym of
R. cramptoni,
R. thorntoni being a junior synonym. Adam S. Smith (2007) and Smith and Gareth J. Dyke (2008) considered this species to be valid. thus it should be in its own genus as suggested by Smith and Dyke (2008). Following this, it has been placed in its own genus,
Atychodracon. (Smith, 2015).
Thaumatosaurus The name
Thaumatosaurus, which means 'wonder reptile', belonged to a genus of plesiosaur that was described by palaeontologist
Christian Erich Hermann von Meyer, back in 1841. Meyer described the species
Thaumatosaurus oolithicus based on partial skull, vertebral and limb remains, that were found in the
Posidonia Shale of
Holzmaden,
Baden-Württemberg,
Germany. In 1856, Meyer published a full description of
Thaumatosaurus and later provided figures of the specimen.
Richard Lydekker (1889) regarded
Rhomaleosaurus as a synonym of
Thaumatosaurus because Richard Lydekker and Harry G. Seeley "refused steadfastly to recognize the generic and specific names proposed by one another". Lydekker referred continuously to the name
Thaumatosaurus, instead of
Rhomaleosaurus. Fraas (1910) recognized both generic names in his original description of
R. victor (now
Meyerasaurus), but referring to the new species "Thaumatosaurus" victor. Many other researchers adopted the name "Thaumatosaurus". Today this taxon is regarded as a
nomen dubium because the holotype can be referred to Pliosauroidea indet at best. The diagnostic specimens which previously were regarded as
Thaumatosaurus's specimens, now represent the holotypes of
Eurycleidus,
Meyerasaurus and
Rhomaleosaurus. ==Phylogeny==