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…

Stratesaurus

Post author:Adam S. Smith
Post published:15/10/2020
Post category:Genus page

Stratesaurus skull reconstruction in lateral view. From Benson, Evans and Taylor (2015).

Stratesaurus is a very small-bodied basal plesiosaur known from the lowermost Jurassic (Blue Lias Formation) of Street, Somerset . Stratesaurus is represented by three specimens. The holotype specimen (OUMNH J.10337) was named and briefly described by Benson, Evans and Druckenmiller (2012), and later described in detail along with two referred specimens by…

Thalassiodracon

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

Thalassiodracon lectotype specimen (NHMUK 2018*).

The species Plesiosaurus hawkinsii was introduced in 1838 for a small plesiosaurian from Street, Somerset. The new genus name Thalassiodracon was erected decades later following an examination of a referred skull in Cambridge (CAMSM J.46986). Thalassiodracon is from the Rhaetian-Hettangian boundary, so it is latest Triassic or earliest Jurassic in age. Thalassiodracon…

Macroplata

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

Macroplata is a rhomaleosaurid plesiosaur from the Lower Jurassic of Warwickshire, UK. Macroplata was named and briefly described by Swinton (1930a) based on a single skeleton from Harbury, Warwickshire, and the skeleton was redescribed in detail by Ketchum and Smith (2010). Photograph of Macroplata tenuiceps in situ in Harbury, Warwickshire. White (1940)…

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…

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…