Classification

Sauropterygia > Eosauropterygia > Eusauropterygia > Pistosauroidea > Plesiosauria > Pliosauroidea > Pliosauridae

Species:

S. vorax Andrews, 1909 (Type species)

Material

The type specimen is an almost complete, but crushed, skeleton in the Natural History Museum, London (BMNH R. 3319).

Distribution

Type locality: Callovian, Oxford Clay, Peterborough, England. Also known from the Callovian and Bajocian of France, and the Tithonian of India.

Images

Title image at top of page: specimen R.3319 in ventral view.

1 2 3 4

1. Plate iii from Andrews 1913 (book available here), showing the holotype (R. 3319) skull of Simolestes in dorsal and ventral view together with a cervical vertebra in various views, and a tooth.

2 and 3. Cast of the Peterborough specimen of Simolestes vorax, originally identified at Liopleurodon Dawn (1991). 3. shows detail of the snout. This cast was part of the Walking with Dinosaurs exhibit, these photos were taken in the Bristol Museum.

4. The original specimen on display in the Peterborough Museum (image courtecy of the "fossilkid" Jamie Jordan, who owns the World Fossil Forum)

Discussion

Simolestes has variously been allied with the Pliosauridae and the Rhomaleosauridae. The most noticeable difference between Simolestes and the other pliosaur taxa in the Oxford Clay (Pliosaurus, Peloneustes), is the much shorter snout and mandibular symphysis in Simolestes, a character shared with typical rhomaleosaurids. However, this is possibly a convergent character. Old descriptions of this taxon make note of the spatulate symphysis and premaxilla with its "rosette" of protruding teeth, however it is now known from other specimens of Simoletes (such as the Peterbprough specimen figured above) that this feature is a result of crushing and the teeth were actually positioned much more vertically in the jaws in life. Simolestes vorax was most recently studied by Noe in his unpublished PHD thesis.

Other species of Simoletes

Simolestes novackianus was named by Huene (1938) based on a mandible from Ethiopia. Tarlo (1960) noted that it differed only in the details of the tooth ornamentation but accepted its validity. Later, Bardet and Hua (1996) recognised that Simolestes nowackianus is actually a teleosaurid crocodile, the species therefore does not belong to Simolestes.

Bardet et al referred another species to Simolestes in 1991: the species S. indicus is from India and was named by Lydekker in 1877 who originally referred it to Plesiosaurus and later to Thaumatosaurus = Rhomaleosaurus. S. indicus differs from other species of Simolestes in having equally sized tooth alveoli in the symphysis (in other species alveoli 3 and 4 are enlarged) and a "peculiar symphyseal protruberance" (Bardet et al, 1991).

The species Simolestes keileni was introduced by Godefroit (1994) for a fragmentary specimen from the Bajocian of France. This species differs from other species only in its crown ornamentation.

Page last updated June 2007. Adam Stuart Smith.