Meyerasaurus

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

The holotype specimen of Meyerasaurus (SMNS 12478) from the Posidonia-Schiefer, Holzmaden, Germany.

M. victor was originally described and figured by Fraas (1910). Historically, M. victor has been regarded as a species of Rhomaleosaurus and is often associated in the literature under the defunct name ‘Thaumatosaurus’. See my article about this history of ‘Thaumatosaurus‘ here. Smith and Vincent (2010) identified M. victor as generically distinct from Rhomaleosaurus and erected the new name...

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) referred the species Plesiosaurus longirostris to Macroplata, and...

Liopleurodon

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

Mounted skeleton of Liopleurodon ferox in the Tubingen Museum, Germany (from Martill and Naish, 2000).

Liopleurodon is a pliosaur that hardly needs introduction since appearing as the villain in the BBC’s ‘Walking with Dinosaurs’ TV series. This led to popular misconceptions about the size of Liopleurodon, which is known to have reached adult sizes in the region of seven metres long, nowhere near the gargantuan 25m estimate proposed by the series and later perpetuated elsewhere....

Kimmerosaurus

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

Skull of Kimmerosaurus. From Brown (1981).

Kimmerosaurus is a poorly known cryptoclidid plesiosaur known only from skull and neck material (Brown 1981, Brown et al. 1986). It differs from other plesiosaurs in the large number of needle-like teeth in its jaws, and in the form of its teeth, which are completely smooth and lack the longitidinal ridges present in other plesiosaurs. Brown et al. (1986) compared...

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 Elasmosauridae (Bardet 1995, Bardet et al. 1999). 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 old adult individuals. This makes Cryptoclidus one of...

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 of plaster cast (BGS GSM 118410) of the...

Attenborosaurus

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

Photograph of the holotype of Attenborosaurus, before it was destroyed. The skeleton was mounted in a block together with a cast of the opposite side of the body and the opposite side of the head (from Swinton, 1949)

Attenborosaurus is an unusual plesiosaur because it combines a long neck with a relatively large head. It is classified as a pliosaur in some classifications, but some phylogenies place it in a more basal position. The genus was introduced for ‘Plesiosaurus’ conybeari, a species originally described by Sollas (1881). Bob Bakker coined the new genus name to honour the esteemed...

Apractocleidus

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

Cryptoclidus (the type specimen of 'Apractocleidus', V.1091, with the tail of V.1104 and a replica head) in the Hunterian Museum, Glasgow, Scotland. Photo by Adam S. Smith. 2007.

The genus and species ‘Apractocleidus teretipes‘ was erected by Smellie (1916). Smellie (1915) provided a preliminary account of the specimen before he named it. The specimen is now regarded as an old-adult individual of Cryptoclidus. The taxon ‘Apractocleidus‘ is therefore considered a junior synonym of Cryptoclidus. The specimen was collected by Alfred Leeds and acquired by the Hunterian Museum, Glasgow....

Archaeonectrus

Post author:Adam S. Smith
Post published:21/07/2018
Post category:Genus page Plesiosauria Pliosauroidea Rhomaleosauridae

Archaeonectrus illustration (From Novozhilov 1964)

The genus Archaeonectrus was proposed by Novozhilov (1964) for ‘Plesiosaurus’ rostratus, a species named by Owen (1865). By modern standards, Owen’s (1865) original description is rather inadequate. One notable characteristic of Archaeonectrus rostratus is the relatively small size of the limbs relative to its body. It has been classified as a pliosauroid, sometimes within the Rhomaleosauridae. Archaeonectrus rostratus is the...