Plesiosuchus

Plesiosuchus Temporal range: Late Jurassic, 154–149 Ma PreЄ Є O S D C P T J K Pg N ↓
Holotype skull NHMUK PV OR40103
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Suborder:	†Thalattosuchia
Family:	†Metriorhynchidae
Tribe:	†Geosaurini
Genus:	†Plesiosuchus Owen, 1884
Type species
†Plesiosuchus manselii (Hulke, 1870 [originally Steneosaurus])

Plesiosuchus is an extinct genus of geosaurine metriorhynchid crocodyliform known from the Late Jurassic (late Kimmeridgian to early Tithonian stage) of Dorset, England and possibly also Spain. It contains a single species, Plesiosuchus manselii.

The type and referred specimens of Plesiosuchus were discovered by John Clavell Mansel-Pleydell in the 1860s alongside the remains of several other large-bodied marine reptiles along the coast of Dorset. Mansel-Pleydell gave these remains to the British Museum (now in the Natural History Museum) in 1866. Part of the holotype of P. manselii (NHMUK PV OR40103a) was first described by John Hulke in 1869. He referred it to Steneosaurus rostro-minor Geoffroy (1825), alongside Dakosaurus maximus and other specimens. Initially, the skull (NHMUK PV OR40103) was believed to be pliosaurian; it was the preparator Mr Davies that suggested a crocodylian nature for the skull. In 1870, Hulke described the skull, which is preserved in two sections: the rostrum and the occiput. Hulke suggested that "this head and the lower jaw both belonged to one individual" as both the same dimensions and were discovered in close proximity in a reef exposed at low water in Kimmeridge Bay. Some material was destroyed due to pyrite decay while the isolated bone fragment referred to as the "upper maxilla" has never been figured and cannot be located. Richard Owen erected the genus Plesiosuchus for S. manselii in 1884 as he considered it to be more similar morphologically to extant crocodylians than to Steneosaurus. Woodward (1885) referred the species to the genus Dakosaurus. Lydekker (1888) synonymized P. manselii with Dakosaurus maximus while Fraas (1902) regarded the two species to be synonymous or closely related. Phylogenetic analyses of Young & Andrade (2009), Cau & Fanti (2011) and Young et al. (2011) support the hypothesis that the two are separate species of Dakosaurus. Young et al. (2012) resurrected the genus name Plesiosuchus as their phylogenetic analysis found a paraphyletic Dakosaurus and suggested more basal position for P. manselii within Geosaurini than previously thought.