Plesiosaur size

A plesiosaur.

Plesiosaurs are extinct marine reptiles.

Record sizes

Plesiosaur skeleton of Meyerasaurus in the Museum am Löwentor, Stuttgart, seen from below

In general, plesiosaurians varied in adult length from between 1.5 metres (5 ft) to about 15 metres (49 ft). The group thus contained some of the largest marine apex predators in the fossil record, roughly equalling the longest ichthyosaurs, mosasaurids, sharks and toothed whales in size. Some plesiosaurian remains, such as a 2.9 metres (10 ft) long set of highly reconstructed and fragmentary lower jaws preserved in the Oxford University Museum and referable to Pliosaurus rossicus (previously referred to Stretosaurus[1] and Liopleurodon), indicated a length of 17 metres (56 ft). However, it was recently argued that its size cannot be currently determined due to their being poorly reconstructed. MCZ 1285, a specimen currently referable to Kronosaurus queenslandicus, from the Early Cretaceous of Australia, was estimated to have a skull length of 2.85 m (9 ft).[2]

Pliosaurs

There is much controversy over the largest known of these reptiles. Fossil remains of a pliosaur nicknamed as Predator X have been discovered and excavated from Norway in 2008. This pliosaur has been estimated at 15 metres (49 ft) in length and 45 metric tons (50 short tons) in weight.[3][4] However, in 2002, a team of paleontologists in Mexico discovered the remains of a pliosaur nicknamed as Monster of Aramberri, which is also estimated at 15 metres (49 ft) in length.[5] This specimen is however claimed to be a juvenile and has been attacked by a larger pliosaur.[6] Some media sources claimed that Monster of Aramberri was a Liopleurodon but its species is unconfirmed thus far.[5] Another very large pliosaur was Pliosaurus macromerus, known from a single 2.8 m long incomplete mandible. It may have reached 18 metres (59 ft), assuming the skull was about 17% of the total body length.[7]

Longest pliosaurs

  1. "NHM symphysis": 9–15 m (30–49 ft)[8]
  2. Pliosaurus funkei: 10–13 m (33–43 ft)[9]
  3. Pliosaurus macromerus: 12.7 m (42 ft)[8]
  4. Kronosaurus queenslandicus: 10.9–12.5 m (36–41 ft)[8]
  5. "The Monster of Aramberri": 7.2–12.4 m (24–41 ft)[8]
  6. Simolestes vorax: 10 m (33 ft)[10]
  7. Pliosaurus brachyspondylus: 9.1 m (30 ft)[8]
  8. Kronosaurus boyacensis: 6–9.5 m (20–31 ft)[8]
  9. Pliosaurus portentificus: 8.5 m (28 ft)[8]
  10. Brachauchenius lucasi: 7.8 m (26 ft)[8]

Heaviest pliosaurs

In 2002, the discovery of a very large pliosauroid was announced in Mexico. This pliosauroid came to be known as the "Monster of Aramberri". The size of this specimen has been estimated to be about 49 feet (15 meters) long and it had a 10-foot (3 meter) long skull. Consequently, although widely reported as such, it does not belong to the genus Liopleurodon.[11] The remains of this animal, consisting of a partial vertebral column, were dated to the Kimmeridgian of the La Caja Formation.[12] The fossils were found much earlier, in 1985, by a geology student and were at first erroneously attributed to a theropod dinosaur by Hahnel.[13] The remains originally contained part of a rostrum with teeth (now lost).

In August 2006, palaeontologists of the University of Oslo discovered the first remains of a pliosaur on Norwegian soil. The remains were described as "very well preserved, as well as being unique in their completeness". The large animal was determined to be a new species of Pliosaurus.[9] In the summer of 2008, the fossil remains of the huge pliosaur were dug up from the permafrost on Svalbard, a Norwegian island close to the North Pole.[14] The excavation of the find is documented in the 2009 History television special Predator X.

On 26 October 2009, palaeontologists reported the discovery of potentially the largest pliosauroid yet found. Found in cliffs near Weymouth, Dorset, on Britain's Jurassic coast, the fossil had a skull length of 7 feet 10 1/2 inches (2.4 meters) and a body length of 52 feet 6 inches (16 meters). Palaeontologist Richard Forrest told the BBC: "I had heard rumours that something big was turning up. But seeing this thing in the flesh, so to speak, is just jaw dropping. It is simply enormous."[15]

List

  1. Pliosaurus macromerus: 19.2 t (18.9 long tons; 21.2 short tons)[8]
  2. "The Monster of Aramberri": 3.6–17.8 t (3.5–17.5 long tons; 4.0–19.6 short tons)[8]
  3. Kronosaurus queenslandicus: 10.6–12.1 t (10.4–11.9 long tons; 11.7–13.3 short tons)[8]

Plesiosaurs

The longest known plesiosauroid was Elasmosaurus at 14 metres (46 feet) long.

Longest plesiosaurs

  1. Elasmosaurus platyurus: 14 m (46 ft)[16]
  2. Hydrotherosaurus alexandrae: 13 m (43 ft)[17]

Heaviest plesiosaurs

  1. Elasmosaurus platyurus: 2 t (2.0 long tons; 2.2 short tons)[16]

References

  1. ↑ Tarlo, L.B.H., 1959, "Stretosaurus gen nov., a giant pliosaur from the Kimmeridge Clay", Palaeontology 2(2): 39-55
  2. ↑ Benson, R. B. J.; Evans, M.; Smith, A. S.; Sassoon, J.; Moore-Faye, S.; Ketchum, H. F.; Forrest, R. (2013). Butler, Richard J, ed. "A Giant Pliosaurid Skull from the Late Jurassic of England". PLoS ONE 8 (5): e65989. doi:10.1371/journal.pone.0065989.
  3. ↑ Alleyne, Richard (2009-03-17). "Biggest and smallest prehistoric predators unearthed". London: The Daily Telegraph. Retrieved 2009-03-17.
  4. ↑ Coghlan, Andy (2009-03-17). "Fossil of 'ultimate predator' unearthed in Arctic". New Scientist. Retrieved 2009-03-17.
  5. 1 2 Buchy, M.-C.; Frey, E.; Stinnesbeck, W.; López-Oliva, J.G. (2003). "First occurrence of a gigantic pliosaurid plesiosaur in the late Jurassic (Kimmeridgian) of Mexico". Bulletin de la Société Géologique de France 174 (3): 271–278. doi:10.2113/174.3.271.
  6. ↑ "Monster von Arramberri". Retrieved 6 February 2010.
  7. ↑ "The Cumnor monster mandible". Retrieved 31 October 2011.
  8. 1 2 3 4 5 6 7 8 9 10 11 McHenry, Colin Richard (2009). "Devourer of Gods: the palaeoecology of the Cretaceous pliosaur Kronosaurus queenslandicus" (PDF): 1–460.
  9. 1 2 Espen M. Knutsen, Patrick S. Druckenmiller and Jørn H. Hurum (2012). "A new species of Pliosaurus (Sauropterygia: Plesiosauria) from the Middle Volgian of central Spitsbergen, Norway". Norwegian Journal of Geology 92 (2–3): 235–258. ISSN 0029-196X. Low resolution pdf High resolution pdf
  10. ↑ Forrest, R. (2000). A large rhomaleosaurid pliosaur from the Upper Lias of Rutland. Mercian Geologist, 15(1), 37-40.
  11. ↑ http://www.plesiosaur.com/plesiosaurs/liopleurodon.php
  12. ↑ M.-C. Buchy, E. Frey, W. Stinnesbeck, J.-G. Lopez-Oliva (2003) "First occurrence of a gigantic pliosaurid plesiosaur in the late Jurassic (Kimmeridgian) of Mexico", Bull. Soc. geol. Fr., 174(3), pp. 271-278
  13. ↑ Hahnel W. (1988) "Hallazgo de restos de dinosaurio en Aramberri, N.L., Mexico",Actas Fac. Cienc. Tierra UANL Linares, 3, 245-250.
  14. ↑ Fox News: Predator X Was Most Fearsome Animal to Swim Oceans
  15. ↑ Morelle, Rebecca (27 October 2009). "Colossal 'sea monster' unearthed". BBC News.
  16. 1 2 "Elasmosaurus - paleofilescom".
  17. ↑ Welles, S.P. (1943). Elasmosaurid plesiosaurs with a description of the new material from California and Colorado. University of California Memoirs 13. pp. 125–254
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