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Microcleidus brachypterygius

Reptilia - Sauropterygia - Microcleididae

Taxonomy
Plesiosaurus brachypterygius was named by Huene (1923). Its type specimen is GPIT ⁄ 477 ⁄ 1 ⁄ 1, a skeleton, and it is a 3D body fossil. Its type locality is Holzmaden, Quarry 29 (=Steinbruch 29), Ohmden; Lias epsilon II, 4, which is in a Falciferum offshore shale in the Posidonia Shale Formation of Germany.

It was synonymized subjectively with Plesiosaurus guilelmiimperatoris by Storrs (1997); it was recombined as Hydrorion brachypterygius by Grossmann (2007); it was recombined as Microcleidus brachypterygius by Benson et al. (2012).

Synonymy list
YearName and author
1923Plesiosaurus brachypterygius Huene pp. 3-20 figs. pl. 1
1963Plesiosaurus brachypterygius Persson p. 20
2000Plesiosaurus brachypterygius Maisch and Rücklin pp. 30-37 figs. 1-5
2001Plesiosaurus brachypterygius O'Keefe p. 11
2007Hydrorion brachypterygius Grossmann p. 549 fig. 7
2012Microcleidus brachypterygius Benson et al. fig. 4

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RankNameAuthor
kingdomAnimalia()
Triploblastica
Nephrozoa
Deuterostomia
phylumChordataHaeckel 1847
subphylumVertebrata
superclassGnathostomata
Osteichthyes()
Sarcopterygii
subclassDipnotetrapodomorpha(Nelson 2006)
subclassTetrapodomorpha()
Tetrapoda()
Reptiliomorpha
Anthracosauria
Batrachosauria()
RankNameAuthor
Cotylosauria()
Amniota
Sauropsida
classReptilia
subclassEureptilia()
Romeriida
Diapsida()
orderSauropterygia
Pistosauria(Baur 1890)
Plesiosauria(de Blainville 1835)
superfamilyPlesiosauroideaWelles 1943
familyMicrocleididae
genusMicrocleidus
speciesbrachypterygius()

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

Diagnosis
ReferenceDiagnosis
M. W. Maisch and M. Rücklin 2000"A definite diagnosis can only be given after an osteological re-examination of Plesiosaurus guilelmiimperatoris. At present the two species are clearly distinguishable by the length of the fore- and hindpaddles, which are only about half as long in Plesiosaurus brachypterygius than in P. guilelmiimperatoris of comparable size. According to Dames (1895), P. guilelmiimperatoris only possesses 14 maxillary teeth as compared to 16 in P. brachypterygius and about 18 in Plesiosaurus dolichodeirus (Storrs 1997). From Dames’ figures it appears, however, possible that there were originally two or three more maxillary teeth. Otherwise the skulls of the two Upper Liassic species are apparently quite similar. P. brachypterygius differs from P. dolichodeirus mainly by the following features of the skull: there are only 16 teeth in the maxilla; the orbit is smaller and more anteriorly situated; the processus ascendentes of the premaxillaries are shorter and separated posteriorly by the frontals; the jugal is excluded from the orbital margin; the foramen parietale is smaller; the frontals are excluded from the orbital margin but reach the foramen parietale posteriorly; the prefrontals arenarrower and more elongate, and meet the postfrontals posteriorly; the occipital rami of the squamosals do not meet in the midline and are restricted to the occipital surface of the skull; the pterygoids meet in a midline suture below the basis cranii; there is no anterior interpterygoid fenestra; and there are clear foramina incisiva."
F. Grossmann 2007Moderate-sized plesiosauroid, adults with an overall length of up to 3 m and a skull-length of c. 180–200 mm, snout rounded and constricted, with elongated sculpturing, temporal openings larger than orbits; small teeth at the premaxillary-maxillary suture and 4–5 larger teeth in the maxilla and premaxilla near the premaxillary-maxillary suture; parietal foramen situated at the parietal-frontal suture, no jugal-orbit contact, no postorbital-parietal contact, squamosal with a lateral process extending ventrally; vomeronasal opening present, anterior interpterygoid vacuity absent, pterygoids meet in a dorsal median suture ventral to the basis cranii; 29–36 elongated cervical vertebrae, 2–3 sacral vertebrae, four proximal propodials in adults, maximum number of phalanges more than 10 in the third finger; rather short limbs of c. 20 per cent of the overall length in adults.