Microcleidus homalospondylus

Microcleidus Temporal range: Toarcian PreЄ Є O S D C P T J K Pg N
Fossil M. homalospondylus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Superorder:	†Sauropterygia
Order:	†Plesiosauria
Family:	†Microcleididae
Genus:	†Microcleidus Watson, 1909
Type species
Plesiosaurus homalospondylus (Owen, 1865)
Other species
M. macropterus (Seeley, 1865) M. tournemirensis (Sciau et al., 1990) M. melusinae Vincent et al., 2017
Synonyms
M. macropteus Plesiosaurus macropteus Seeley, 1865 M. tournemirensis Plesiosaurus tournemirensis Sciau et al., 1990 Occitanosaurus tournemirensis Bardet et al., 1999

M. macropteus

M. tournemirensis

Microcleidus is an extinct genus of sauropterygian reptile belonging to the Plesiosauroidea. It was about the size of a medium-sized dolphin, reaching a length of 3 metres (9.8 ft). The species has 40 neck vertebrae and a short tail of 28 vertebrae.

Species include: Microcleidus homalospondylus (Owen 1865) and Microcleidus macropterus (Seeley 1865).

Occitanosaurus tournemirensis (originally "Plesiosaurus" tournemirensis), was named by Sciau et al. in 1990, based on a nearly complete skeleton of an animal approximately 4 meters (13 ft) long. It was later found to be a species of Microcleidus.

The following cladogram follows an analysis by Ketchum & Benson, 2011.

"Pistosaurus postcranium"

Augustasaurus hagdorni

Bobosaurus forojuliensis

Pistosaurus

Yunguisaurus liae

Thalassiodracon hawkinsii

Hauffiosaurus spp.

Attenborosaurus conybeari

advanced pliosaurids

NHMUK 49202 [now Anningasaura lymense]

advanced rhomaleosaurids

"Plesiosaurus" macrocephalus

Archaeonectrus rostratus

Macroplata tenuiceps

OUMNH J.10337 [now Stratesaurus taylori]

Seeleyosaurus guilelmiimperatoris

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