Editing Plesiosaurus (section)

===Vertebral column===
[[File:Conybeare Plesiosaur 1824.jpg|thumb|left|Illustration of the skeletal anatomy of a ''Plesiosaurus dolichodeirus'' from Conybeare's 1824 paper that described an almost complete plesiosaur skeleton found by Mary Anning in 1823]]
''Plesiosaurus'' was a moderately sized plesiosaur that grew to {{cvt|2.87|-|3.5|m|ft}} in length.<ref>{{cite journal|first1=W.J.|last1=Sollas|year=1881|title=On a new species of ''Plesiosaurus'' (''P. Conybeari'') from the Lower Lias of Charmouth; with observations on ''P. megacephalus'', Stutchbury, and ''P. brachycephalus'', Owen|journal=Quarterly Journal of the Geological Society of London|volume=37|issue=1–4 |pages=440–480|doi=10.1144/GSL.JGS.1881.037.01-04.42 |s2cid=129977015 |url=https://ia800708.us.archive.org/view_archive.php?archive=/22/items/crossref-pre-1909-scholarly-works/10.1144%252Fgsl.jgs.1873.029.01-02.46.zip&file=10.1144%252Fgsl.jgs.1881.037.01-04.42.pdf}}</ref><ref name=Storrs149>Storrs 1997 pp. 149</ref> There are approximately 40 [[cervical vertebrae]] (neck vertebrae), with different specimens preserving 38 to 42 cervical vertebrae.<ref name=Storrs170>Storrs 1997 pp. 170</ref>  Of the rest of the vertebral column, there are a handful (four or five in the [[holotype]] specimen) of "pectoral" vertebrae from the neck-torso transition,<ref name=Storrs170/> approximately 21 dorsal or back vertebrae, three or more [[sacrum|sacral vertebrae]], and at least 28 [[caudal vertebra]]e.<ref name=Storrs171>Storrs 1997 pp. 171</ref> Generally, the [[body of vertebra|centra]] of the cervical vertebrae are relatively elongated, being slightly longer than tall. The width, however, is usually greater than or equal to the length. The articular surfaces of the cervical centra are "slightly concave and kidney-shaped, with rounded, slightly rugose edges." Small holes called foramina subcentralia are found on the ventral surface of the centra. Some of the dorsals have rugose articular edges, like the cervicals; this feature is typically absent from the caudals.<ref name=Storrs170/>

Ribs are found from the neck to the tail. Cervical ribs are hatchet-shaped and have two articular heads.<ref name=Storrs170/> Dorsal ribs are thick and have only one head. Sacral ribs are "short, robust, and blunt or knob-like on both ends." Caudal ribs have different [[morphology (biology)|morphologies]] depending on their location along the tail, with anterior examples being pointed and more distal examples being "broad and blunt."<ref name=Storrs170>Storrs 1997 pp. 170</ref> ''Plesiosaurus'' also has [[gastralium|gastralia]], also known as "belly ribs." Nine or more sets of gastralia are present between the [[pectoral girdle|shoulder]] and [[pelvis]]. Each set is composed of seven elements: a bone on the midline flanked by three lateral elements.<ref name=Storrs171/>