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 Benson, Evans and Taylor (2015).
The genus contains a single species, Stratesaurus taylori. The genus name comes from ‘Strate’, the name for Street as recorded in the Doomesday Book. The species name honours palaeontologist Michael A. Taylor, who conducted preparation on the specimen, and was involved in its description (but not in its naming!).
Stratesaurus possesses the following diagnostic characters:
Very small adult body size (the skull is 18cm long, so I would estimate the total body length at about 2m)
Five alveoli in each premaxilla
19–21 alveoli in each maxilla
Maxilla lacks rostral constriction
Prominent and posteriorly projecting processes on posterolateral surfaces of anterior cervical prezyga pophyses (autapomorphy)
Pectoral centra proportionally short (a length:anterior height ratio of 0.7) (autapomorphy)
Stratesaurus skull reconstruction in lateral view. From Benson, Evans and Taylor (2015). 
Cranium of the Stratesaurus holotype (OUMNH J.10337) in dorsal view, with interpretation. From Benson, Evans and Taylor (2015). 
Cranium of the Stratesaurus holotype (OUMNH J.10337) in ventral view, with interpretation. From Benson, Evans and Taylor (2015). 
Cranium of a referred specimen (AGT 11) of Stratesaurus in dorsal view, with interpretation. From Benson, Evans and Taylor (2015). 
Skull of a referred specimen (GSM 26035) of Stratesaurus in various views, with interpretations. From Benson, Evans and Taylor (2015).
Stratesaurus taylori
Species
S. taylori
Author
Benson, Evans and Druckenmiller (2012)
Classification
S. taylori
Age
Lower Hettangian
Type location
Street, Somerset, UK
Type specimen
OUMNH J.10337, skull and partial postcranium
Referred material
AGT 11, a skull; GSM 26035, a skull
S. taylori is the type and only species of Stratesaurus.