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Pliosaurus brachydeirus

Reptilia - Sauropterygia - Pliosauridae

Plesiosaurus (Pleiosaurus) brachydeirus was named by Owen (1841). Its type specimen is OXFUM J.9245A,B, J.9285, J.9292-9298 etc, a partial skeleton (teeth, lower and upper jaws, vertebral column, femur, tibia, fibula), and it is a 3D body fossil. Its type locality is Market Rasen, which is in a Kimmeridgian marine horizon in the Kimmeridge Clay Formation of the United Kingdom.

It was synonymized subjectively with Pliosaurus grandis by Owen (1869); it was misspelled as Pliosaurus brachydirus by Lydekker (1889); it was recombined as Pliosaurus brachydeirus by Owen (1842), Seeley (1869), Tarlo (1959), Delair (1960), Tarlo (1960), Bardet et al. (1993), O'Keefe (2001), Noè et al. (2004), Knutsen (2012) and Benson et al. (2013).

  • Plesiosaurus sterrodeirus was named by Seeley (1869). It is a 3D body fossil. Its type locality is Ely, Roswell Pits, which is in a Kimmeridgian marine horizon in the Kimmeridge Clay Formation of the United Kingdom.

    It was recombined as Peloneustes sterrodeirus by Lydekker (1889); it was synonymized subjectively with Pliosaurus brachydeirus by Tarlo (1960).
Synonymy list
YearName and author
1841Plesiosaurus (Pleiosaurus) brachydeirus Owen
1842Pliosaurus brachydeirus Owen pp. 64-65
1869Plesiosaurus sterrodeirus Seeley
1869Pliosaurus brachydeirus Seeley pp. 104-105, 137
1889Peloneustes sterrodeirus Lydekker
1889Pliosaurus brachydirus Lydekker pp. 123-128 fig. 37
1959Pliosaurus brachydeirus Tarlo p. 284
1960Pliosaurus brachydeirus Delair pp. 69-70
1960Pliosaurus brachydeirus Tarlo p. 152
1993Pliosaurus brachydeirus Bardet et al. p. 390
2001Pliosaurus brachydeirus O'Keefe p. 14
2004Pliosaurus brachydeirus Noè et al. p. 14
2012Pliosaurus brachydeirus Knutsen pp. 260-267
2013Pliosaurus brachydeirus Benson et al.

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phylumChordataHaeckel 1847
subclassDipnotetrapodomorpha(Nelson 2006)
Pistosauria(Baur 1890)
Plesiosauria(de Blainville 1835)
familyPliosauridaeSeeley 1874

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.

R. Lydekker 1889Considerably smaller than P. macromerus. Teeth (fig. 37) with the carina) strongly developed, and the intercarinal space large and flat, without any trace of vertical ridges ; 35 teeth in lower jaw, and mandibular teeth increasing in size till the 12th cervical vertebras without bevelled edges to the terminal faces of the centra, with the costal facets moderately prominent, unequal, and not deeply excavated ; and in the anterior region with a mammilla surrounding the central puncture ; texture of bone very fine and smooth. Humerus and femur with small proximal trochanter; femur with the shaft suddenly contracted in the middle, and expanding gradually at both extremities.
L. B. Tarlo 1959Mandible with long symphysis bearing 10-12 teeth of which the anterior 5-6 are large and caniniform; total of 30-38 teeth in each ramus. Cervical vertebrae short, length about half width or height; cervical ribs double-headed. Scapula triradiate with dorsal process directed laterally and ventral plate expanded medially; coracoid elongated with postero-lateral expansion; ischia elongated; propodials long, compressed dorso-ventrally, expanded distally; epipodials short
E. M. Knutsen 2012Pliosaurus with approximately 70 teeth in the lower jaw, 8-9 or more pairs of symphyseal teeth in dorsal view; 5 or more premaxillary teeth; Type III retroarticular process; cervical vertebrae with a smooth ventral surface and a ventral keel.
R. B. J. Benson et al. 2013Species of Pliosaurus with the following unique character combination: high dentary alveolar count including 24 postsymphysial alveoli (>35 total) and an estimated total count of 36–37; high count of symphysial dentary alveoli (>11), estimated as 12–13; fully trihedral teeth; mediolateral expansion of premaxilla and maxillary caniniform region relatively slight; six closely-spaced premaxillary alveoli; distalmost premaxillary alveolus similar in size to more mesial alveoli (i.e. non-‘anisodont’ or non-‘heterodont’ premaxillary dentition); diastema present between maxillary and premaxillary alveolar rows; premaxilla–parietal suture located level with the anterior region of the orbit; broad, low, anteroposteriorly oriented ridge on ventral surfaces of cervical centra; epipodials with flat proximal articular surfaces (although this may result from the subadult ontogenetic status of the holotype and only specimen).