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Pleiosaurus macromerus

Reptilia - Sauropterygia - Pliosauridae

Taxonomy
Pleiosaurus macromerus was named by Phillips (1871) [Spelled "Pleiosaurus" in the text]. Its type specimen is Lectotype: OUMNH J. 10441, a set of vertebrae (cervical vertebra), and it is a 3D body fossil. Its type locality is Shotover Railway Cutting (Great Western Railway excavation), near Swindon, which is in a Kimmeridgian marine horizon in the Kimmeridge Clay Formation of the United Kingdom.

It was recombined as Pliosaurus macromerus by Lydekker (1889), Delair (1960), Malakhov (1999), Noè et al. (2004) and Knutsen (2012); it was recombined as Stretosaurus macromerus by Tarlo (1959) and Tarlo (1960); it was recombined as Liopleurodon macromerus by Halstead (1989) and Bardet et al. (1993); it was considered a nomen dubium by Benson et al. (2013).

Synonyms
Synonymy list
YearName and author
1838Ischyrodon meriani Meyer
1871Pleiosaurus macromerus Phillips p. 354 figs. CXLVIII-CLI
1872Polyptychodon archiaci Deslongchamps figs. pl. 5, figs 1-2
1889Pliosaurus macromerus Lydekker pp. 131-139 figs. 41-43
1959Stretosaurus macromerus Tarlo
1960Pliosaurus macromerus Delair p. 71
1960Stretosaurus macromerus Tarlo pp. 159-160
1989Liopleurodon macromerus Halstead p. 38
1993Liopleurodon macromerus Bardet et al. p. 390
1999Pliosaurus macromerus Malakhov p. 241
2004Pliosaurus macromerus Noè et al. p. 23
2012Pliosaurus macromerus Knutsen p. 269

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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)
familyPliosauridaeSeeley 1874
Thalassophonea
genusPleiosaurus()
speciesmacromerus

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
L. B. Tarlo 1959Teeth trihedral in cross-section, outer surface smooth and flat; mandible with short symphysis bearing five to six large caniniform teeth, total of about twenty-five teeth in each ramus; cervical vertebrae short, length less than half width or height, ventral keel absent, cervical ribs double headed; caudal vertebrae without chevron bone facets; scapula triradiate with dorsal process produced anteriorly; coracoid long with postero-lateral expansion; ischium elongated; propodials long, compressed dorsoventrally, slightly expanded distally; epipodials short.
D. V. Malakhov 1999The length of the centra is less than half of height or width. The superior rib facet of the cervicals is almost triangular in outline. The ventral surface of the cervicals is sculptured with continuous well developed rugosity. The ventral keel is absent on the cervicals, ventral lip is not developed. The ventral surface of the dorsal vertebrae bears double-stripped rugosity. Caudal vertebrae with chevron bone facets. There is well developed boss on the anterior and posterior surfaces of all vertebrae.
E. M. Knutsen 2012Pliosaurus with approximately 50 teeth in the lower jaw, 6 pairs of symphyseal teeth in dorsal view; Type III retroarticular process.