Dinosaurs Codexery

Plesiosaurus

Early Jurassic marine reptile with a long neck and small head.

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Plesiosaurus

the paleobear · via Wikipedia: Plesiosaurus · CC BY 2.0

The name "near lizard" was coined by William Conybeare and Henry De la Beche to indicate it was more like a normal reptile than Ichthyosaurus.[1] Plesiosaurus* serves as the model genus for the order Plesiosauria, being the first member of that group to receive a formal scientific description.[1]

Scientific classification

  1. KingdomAnimalia
  2. PhylumChordata
  3. ClassReptilia
  4. Superorder†Sauropterygia
  5. Order†Plesiosauria
  6. Superfamily†Plesiosauroidea
  7. Family†Plesiosauridae
  8. Genus†Plesiosaurus
  9. SpeciesPlesiosaurus dolichodeirus

Named by Conybeare, 1824

Sources: Wikipedia taxobox: Plesiosaurus (CC BY-SA 4.0)

How big is it?

Size comparison: Plesiosaurus and a personA 3.5 m long plesiosaurus drawn to scale next to a 1.8 m tall person. Schematic shapes, not a likeness.3.5 m1.8 m

Largest length in the source, 3.5 m, next to a 1.8 m person.

Diagram: drawn by Codexery, schematic shapes to scale (not a likeness). Length: Wikipedia: Plesiosaurus

Quick Facts

Species
dolichodeirus

Facts from the source article.

Biology and range

Plesiosaurus was a moderately sized plesiosaur reaching 2.87 to 3.5 m in length.[2] The cranial proportions of Plesiosaurus are modest when set against those of other plesiosaur genera.[3] The skull's length greatly exceeds its width, and the roughly circular eye openings are situated near the midpoint of the skull's length.[3] The dentition consists of simple, conical teeth that resemble needles; they are gently curved and come to sharp points.[4][5]

Each upper jaw tooth row contains between 20 and 25 teeth, while the lower jaw tooth row holds 24 teeth.[5] The vertebral column of the neck comprises roughly 40 cervical vertebrae, with known individuals having counts ranging from 38 to 42.[2] Researchers infer that Plesiosaurus preyed upon belemnites, fish, and similar animals, employing its U-shaped jaw and pointed teeth as a trapping mechanism.[6] Locomotion was achieved through the use of its flippers, since the tail was too brief to provide significant propulsion.[7]

Like many sea snakes, Plesiosaurus is believed to have given birth to live offspring while in the water.[7] Only in the Lyme Regis region of Dorset can unequivocal remains of Plesiosaurus dolichodeirus be found.[8]

What the specialist sources record

The GBIF Backbone Taxonomy lists Plesiosaurus dolichodeirus Conybeare, 1824 as an accepted species, with 57 occurrence records as of 3 October 2026.[9] A 2012 cladistic analysis by Benson and colleagues placed Plesiosaurus within the plesiosaurian evolutionary tree.[10][11]

References

  1. Wikipedia, "Plesiosaurus" (CC BY-SA 4.0), which cites: De la Beche, H. T. & W. D. Conybeare. (1821). Notice of the discovery of a new fossil animal, forming a link between the Ichthyosaurus and crocodile, together w (original not read by us) en.wikipedia.org
  2. Wikipedia, "Plesiosaurus" (CC BY-SA 4.0), which cites: Sollas, "On a new species of Plesiosaurus (P. Conybeari) from the Lower Lias of Charmouth; with observations on P. megacephalus, Stutchbury, and P. brachycephalus, Owen", Quarterly Journal of the Geological Society of Lo; Storrs 1997 pp. 149; Storrs 1997 pp. 170; Storrs 1997 pp. 170; Storrs 1997 pp. 171 (we also read that source) en.wikipedia.org
  3. Wikipedia, "Plesiosaurus" (CC BY-SA 4.0), which cites: Storrs 1997 pp. 166; Storrs 1997 pp. 165; Storrs 1997 pp. 165; Storrs 1997 pp. 167; Storrs 1997 pp. 165; Storrs 1997 pp. 166; Cruickshank 1991; Storrs 1997 pp. 165; Storrs 1997 pp. 165; Storrs 1997 pp. 166; Storrs 1997 pp. 167; Storrs 1997 pp. 165; Storrs 1997 pp. 165; Storrs 1997 pp. 165; Storrs 1997 pp. 165; Taylor and Cruickshank 1993; Storrs 1997 pp. 165 (original not read by us) en.wikipedia.org
  4. Wikipedia, "Plesiosaurus" (CC BY-SA 4.0), which cites: Storrs 1997 pp. 169. (original not read by us) en.wikipedia.org
  5. Wikipedia, "Plesiosaurus" (CC BY-SA 4.0), which cites: Storrs 1997 pp. 166; Storrs 1997 pp. 165; Storrs 1997 pp. 166; Storrs 1997 pp. 169. (original not read by us) en.wikipedia.org
  6. Wikipedia, "Plesiosaurus" (CC BY-SA 4.0), which cites: "Plesiosaur bottom-feeding shown", 17 October 2005 (original not read by us) en.wikipedia.org
  7. Wikipedia, "Plesiosaurus" (CC BY-SA 4.0), which cites: "Sticking your neck out: How did plesiosaurs swim with such long necks?" (original not read by us) en.wikipedia.org
  8. Wikipedia, "Plesiosaurus" (CC BY-SA 4.0), which cites: Storrs 1997 pp. 148; Storrs 1997 pp. 179 (original not read by us) en.wikipedia.org
  9. GBIF Backbone Taxonomy and occurrence index, Plesiosaurus dolichodeirus (taxon key 4823598). CC BY 4.0 (backbone); counts are facts. gbif.org
  10. Roger Benson, "High Diversity, Low Disparity and Small Body Size in Plesiosaurs (Reptilia, Sauropterygia) from the Triassic–Jurassic Boundary", PLoS ONE (2012), doi:10.1371/journal.pone.0031838. OpenAlex metadata CC0; paper not read. doi.org
  11. Wikipedia, "Plesiosaurus" (CC BY-SA 4.0), which cites: Benson, "High Diversity, Low Disparity and Small Body Size in Plesiosaurs (Reptilia, Sauropterygia) from the Triassic–Jurassic Boundary", PLOS ONE, 2012 (we also read that source) en.wikipedia.org

Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Plesiosaurus (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.

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Sources

Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.

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