Cryptoclidus

Genus

Cryptoclidus

Author

Seeley, 1892

Classification

Cryptoclidus

Age

Late Jurassic and Lower Cretaceous

Location

Peterborough, Cambridgeshire and Bedfordshire, UK; Normandy, France

Type species

C. eurymerus

Other species

C. richardsoni

Referred material

To be compiled

Cryptoclidus, often wrongly spelled ‘Cryptocleidus’ after Andrews (1909), is a moderately sized plesiosaur up to 3 metres long. 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 the most studied and best understood of all plesiosaurs.

Full mounted skeletons of Cryptoclidus can be seen in several major museums including the Musee Palaeontologique, Paris; the Natural History Museum, London; the Hunterian Museum, Glasgow; and the American Museum of Natural History, New York.

The genus has diagnostic teeth with reduced ornamentation. Each premaxilla contains six teeth. Cryptoclidus lacks suborbital fenestrae on its palate and has a large anterior interpterygoid vacuity. A small foramen is located along the postorbital-squamosal junction in C. eurymerus.

Cryptoclidus used its numerous sharp teeth to catch squid and fish, or perhaps to sift silty sediments for benthic animals such as crustaceans.

C. richardsoni differs from C. eurymerus only in the form of its humerus, which is more expanded distally. The genus and species ‘Apractocleidus teretipes‘ was introduced by Smellie (1916) for a specimen now regarded as an old-adult specimen of Cryptoclidus.

Referred specimen of Cryptoclidus in the Tubingen Museum, Germany.

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

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

Cryptoclidus illustration by Zdenek Burian.

Cryptoclidus eurymerus. Postcard from the Paris Musee de Paleontologie

Cryptoclidus painting by Zdenek Burian.

Adult Cryptoclidus, American Museum of Natural History, New York.

Adult Cryptoclidus, American Museum of Natural History, New York. Photo by Adam S. Smith

Adult Cryptoclidus, American Museum of Natural History, New York. Photo by Adam S. Smith

Cryptoclidus on land, as depicted in ‘Walking with Dinosaurs’. From Martill and Naish, 2000.

Young individual of Cryptoclidus in the Natural History Museum, London.

Young individual of Cryptoclidus in the Natural History Museum, London. Photo by Adam S. Smith 2005.

3D ‘bust’ of a Cryptoclidus head in the York Museum, UK.

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.