''Megalneusaurus'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of large

pliosaur Pliosauroidea is an extinct clade of plesiosaurs, known from the earliest Jurassic to early Late Cretaceous. They are best known for the subclade Thalassophonea, which contained crocodile-like short-necked forms with large heads and massive tooth ...

that lived in the

Sundance Sea The Sundance Sea was an epeiric sea that existed in North America during the mid-to-late Jurassic Period of the Mesozoic Era. It was an arm of what is now the Arctic Ocean, and extended through what is now western Canada into the central western ...

during the

Kimmeridgian In the geologic timescale, the Kimmeridgian is an age in the Late Jurassic Epoch and a stage in the Upper Jurassic Series. It spans the time between 157.3 ± 1.0 Ma and 152.1 ± 0.9 Ma (million years ago). The Kimmeridgian follows the Oxfordian ...

, ~156-152 million years ago, in the

Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name ...

. It was named by paleontologist W. C. Knight in 1895. The genus and

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

was based upon ribs, vertebrae, a fore-paddle and fragments of the pectoral girdle discovered in the Sundance Formation in

Wyoming Wyoming () is a U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the south ...

, USA in 1895.Knight WC. 1895 A new Jurassic plesiosaur from Wyoming. ''Science'' 2: 449. The species named as ''Megalneusaurus rex'' (meaning "great swimming lizard king") in 1898.Knight WC. 1898. Some new Jurassic vertebrates from Wyoming. ''American Journal of Science'' 4: 378-381. However some of this material has since been lost, although new material has been discovered from the same site.Wahl WR, Ross M, Massare JA. 2007. Rediscovery of Wilbur Knight’s ''Megalneusaurus rex'' site: new material from an old pit. ''Paludicola'' 6 (2): 94-104. Based upon the bones very large size, it appears to have grown to a size comparable to ''

Liopleurodon ''Liopleurodon'' (; meaning 'smooth-sided teeth') is an extinct genus of large, carnivorous marine reptile belonging to the Thalassophonea, a clade of short-necked pliosaurid plesiosaurs. ''Liopleurodon'' lived from the Callovian Stage of the Mi ...

''. Material from southern

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...

have been referred to ''Megalneusaurus'', although this material is from an individual of much smaller size, twice lesser than ''M. rex''.Weems RE, Blodgett RB. 1996
The pliosaurid ''Megalneusaurus'': a newly recognized occurrence in the Upper Jurassic Neknek Formation of the Alaska Peninsula
''U.S. Geological Survey Bulletin'' 2152: 169-175.

Description

''Megalneusaurus'' is said to reach lengths of , though there are some estimates that propose a length of .

Habitat

''Megalneusaurus'' hunted in the warm waters of the

around 150 million years ago. The large, inland sea hosted a wide array of marine reptiles, including the

ichthyosaur Ichthyosaurs (Ancient Greek for "fish lizard" – and ) are large extinct marine reptiles. Ichthyosaurs belong to the order known as Ichthyosauria or Ichthyopterygia ('fish flippers' – a designation introduced by Sir Richard Owen in 1842, altho ...

Baptanodon ''Baptanodon'' is an ichthyosaur of the Late Jurassic period (160-156 million years ago), named for its supposed lack of teeth (although teeth of this genus have since been discovered). It had a graceful long dolphin-shaped body, and its jaws we ...

'',Ilaria Paparella; Erin E. Maxwell; Angelo Cipriani; Scilla Roncacè; Michael W. Caldwell (2017). "The first ophthalmosaurid ichthyosaur from the Upper Jurassic of the Umbrian–Marchean Apennines (Marche, Central Italy)". Geological Magazine. 154 (4): 837–858. doi:10.1017/S0016756816000455. and the cryptoclidid

plesiosaurs The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared ...

Pantosaurus ''Pantosaurus'' ("all lizard") is an extinct genus of plesiosaur from the Late Jurassic ( Oxfordian) of what is now Wyoming. It lived in what used to be the Sundance Sea. It was originally named ''Parasaurus'' ("near lizard") by Othniel Charles M ...

'' and ''

Tatenectes ''Tatenectes'' is a genus of cryptoclidid plesiosaur known from the Upper Jurassic of Wyoming. Its remains were recovered from the Redwater Shale Member of the Sundance Formation, and initially described as a new species of '' Cimoliosaurus ...

''.

References

{{Taxonbar, from=Q1911639 Late Jurassic plesiosaurs Late Jurassic reptiles of North America Jurassic plesiosaurs of North America Sauropterygian genera

Description

Habitat

See also

References