Colymbosaurus

Post author:Adam S. Smith
Post published:18/10/2020
Post category:Colymbosaurinae Cryptoclididae Genus page Plesiosauria Plesiosauroidea

Left hindlimb of Colymbosaurus megadeirus (CAMSM J.29596etc), modified from Benson and Bowdler (2014)

Colymbosaurus is a colymbosaurine (derived cryptoclidid) from the Late Jurassic of the UK and Svalbard, Norway. Two valid species are known, C. megadeirus from the UK, and C. svalbardensis from Svalbard, Norway. The genus is known from the Kimmeridgian, Tithonian, and possibly early Berriasian (Late Jurassic–possibly Early Cretaceous). Benson and Bowdler (2014)…

Muraenosaurus

Post author:Adam S. Smith
Post published:18/10/2020
Post category:Cryptoclididae Genus page Plesiosauria Plesiosauroidea

Restoration of the skeleton of Muraenosaurus in lateral view. From Andrews 1910.

Brown (1981) diagnosed Muraenosaurus as follows: "Plesiosauroids in which the teeth are ornamented with many longitudinal ridges; the dentary bears 19 to 22 teeth on each ramus; the premaxillae bear 5 teeth each, of which the 1st and 5th are small, and the 2nd to 4th are large; the most anterior maxilliary…

Hauffiosaurus

Post author:Adam S. Smith
Post published:17/10/2020
Post category:Genus page Plesiosauria Pliosauridae Pliosauroidea

Holotype (Hauff Uncatalogued) of Hauffiosaurus zanoni as preserved in ventral view. Scale bar = 1 m. From Vincent (2011)

Hauffiosaurus is a basal pliosaurid known from the Lower Jurassic (Toarcian) of the UK and Germany. Hauffiosaurus is a medium to large sized plesiosaur (H. zanoni = 3.4 m, H. tomistomimus, 4.23 m, H. longirostris = 4.83 m) (Smith and Lomax 2019), with a relatively long neck for a pliosaur, and an…

Anningasaura

Post author:Adam S. Smith
Post published:17/10/2020
Post category:Genus page Plesiosauria Pliosauroidea

Anningasaura is a basal plesiosaur from the Lower Jurassic of Lyme Regis, UK, known from a single three-dimensionally preserved skull. The specimen, NHMUK OR49202, was originally described and figured by Andrews (1896), who referred it to 'Plesiosaurus' macrocephalus. It was redescribed and named as the holotype of Anningasaura lymense by Vincent and…

Avalonnectes

Post author:Adam S. Smith
Post published:16/10/2020
Post category:Genus page Plesiosauria Rhomaleosauridae

The holotype specimen of Avalonnectes (NHMUK OR 14550), on display in the Natural History Museum, London. Photo by Chris Crump.

Avalonnectes is a small-bodied basal rhomaleosaurid. Avalonnectes was named by Benson, Evans and Druckenmiller (2012) for a partial skeleton including the rear part of the skull from the lowermost Jurassic of Street, Somerset, UK. The specimen (NHMUK PV OR 14550) was previously referred to Thalassiodracon hawkinsii and is one of many historical…

Eretmosaurus

Post author:Adam S. Smith
Post published:22/07/2018
Post category:Genus page Plesiosauria

Skeleton of Eretmosaurus. Lithograph from Owen (1865).

The genus Eretmosaurus was erected for 'Plesiosaurus' rugosus by Seeley (1874). Eretmosaurus is a rogue taxon in cladistic analyses and researchers have been in disagreement about its taxonomic affinity. Eretmosaurus has been included in several different families: the Rhomaleosauridae based on the anatomy of its girdles (Persson 1963); the Pliosauridae (Brown 1981), the…

Cryptoclidus

Post author:Adam S. Smith
Post published:22/07/2018
Post category:Cryptoclididae Cryptoclidus Genus page Plesiosauria Plesiosauroidea

Skeleton of Cryptoclidus in lateral view. From Brown (1981).

Cryptoclidus, often wrongly spelled 'Cryptocleidus' after Andrews (1909), is a moderately sized plesiosaur with adults about four metres long (Brown 1981). It is known from a large number of individual specimens from the Oxford Clay Formation. Fossils of Cryptoclidus are relatively common, and provide a complete ontogenetic sequence from very young to…

Atychodracon

Post author:Adam S. Smith
Post published:22/07/2018
Post category:Genus page Plesiosauria Pliosauroidea Rhomaleosauridae

Holotype specimen of Atychodracon megacephalus in the Bristol City Museum and Art Gallery (from Swinton, 1948). The specimen was destroyed during the Second World War.

The genus Atychodracon was erected by Smith (2015) to accommodate 'Rhomaleosaurus' megacephalus, because it is generically separarate from Rhomaleosaurus sensu stricto (Smith and Dyke 2008). A. megacephalus is closely related to Eurycleidus and some authors have regarded A. megacephalus as a distinct species of Eurycleidus. Three dimensional scan with texture (colour) removed…