Liopleurodon

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The full and complicated story of the ‘Stretham Pliosaur’ specimen (OXFUM J.35990) is one for another day, but in short it is a substantially complete pliosaur from the Kimmeridge Clay, named ‘ Stretosaurus‘ macromerus by Tarlo (1959) and later reattributed by him (Halstead, 1989) to Liopleurodon macromerus. The Stretham skeleton was retained as the lectotype of Pliosaurus macromerus by Knutsen (2012) but referred to Pliosaurus cf. kevani by Benson et al. (2013) – either way, it is Pliosaurus, not Liopleurodon. I agree with McHenry that the reconstruction may have been based on the ‘Stewartby Pliosaur’ supplemented with information from other pliosaurs, possibly the lectotype of ‘ Stretosaurus’. But it is misleading to call the reconstruction ‘ Stretosaurus‘, especially since significant portions of the Newman & Tarlo reconstruction are implicitly based on Liopleurodon ferox (The ‘Stewartby Pliosaur’). To my eye the hind limb in the reconstruction does resemble the ‘Stewartby Pliosaur’ (from what is visible in the photograph) more than the ‘Stretham Pliosaur’. A PLIOSAUR ( LIOPLEURODON) Ellis, R. 2003. Sea dragons – predators of the prehistoric oceans. University Press of Kansas, 313 pp. While paleontologists had concluded that the Liopleurodon had a maximum length of 25 feet, the series portrayed the animal as long as 80 feet. McHenry (2009) suggested that the reconstruction “ may have been based upon StretosaurusTarlo, 1959″ (p.258) and added that “From vertebral counts of the different body segments and general proportions of the skull it undoubtedly represents a large pliosaurid, perhaps‘ Stretosaurus’( Pliosaurus macromerus)” (p. 370). McHenry also noted that “Tarlo… seemed to imply that the reconstruction was partly based upon the Stretham specimen…”(p.359), and subsequently refers to the reconstruction as the “‘Newman and Tarlo Stretosaurus‘ reconstruction, or the ‘ Stretosaurus’ reconstruction” (e.g. p. 370) and says the reconstruction is “ apparently based upon the Stewartby and Stretham specimens” (p. 370). I’ve bolded key parts to highlight that there’s no direct evidence for this assertion – not that I disagree with it.

Mosasaurs were much bigger and had more powerful jaws than their predecessors, which gave the Liopleurodon real competition. Otherwise called “smooth-sided tooth,” this now-extinct reptile was an apex predator that roamed the oceans between the Middle Jurassic and Late Jurassic periods. The first fossils of this ancient creature were discovered in 1873 in the Boulogne sur Mer region of France. Fossilized tooth of Liopleurodon | Madzia via Wikipedia CC BY-SA 4.0 Since they did not have gills like some whales today, they go to the surface to take a huge gulp of air which can last them for over an hour in the depths of water. Although scientists once exaggerated the size of the Liopleurodon, they have now settled for a more reasonable size.

Halstead, L. B. 1971. Liopleurodon rossicus (Novozhilov) – a pliosaur from the Lower Volgian of the Moscow Basin. Palaeontology, 14, 566-571.

A highly recommended online toy store featuring a wide variety of Papo, Schleich, Safari Ltd., CollectA, and other figures. Knutsen, E. M. 2012. A taxonomic revision of the genus Pliosaurus (Owen, 1841a) Owen, 1841b. Norwegian Journal of Geology, 92, 259–276.Tarlo, L. B. 1959. Stretosaurus gen. nov., a giant pliosaur from the Kimmeridge Clay. Palaeontology, 2, 39-55. McHenry, C. R. 2009. Devourer of Gods: the palaeoecology of the Cretaceous pliosaur Kronosaurus queenslandicus. Unpublished PhD thesis, University of Newcastle.

Historically, the first plesiosaurs existed about 203 million years ago, during the Late Triassic period, and became prominent during the Jurassic Era. Furthermore, in 1999, more people learned about this extinct animal when it was featured in the BBC series Walking With Dinosaurs.It has been gathered that plesiosaurs most likely evolved from archosaurians and turtles that returned to the sea. In addition, the animal was portrayed as mostly toothless, only possessing a crescent of curved fangs which extended from the front of the upper and lower jaws. Inanimate objects were not left out; they likely always tried to bite every big thing they discovered. From its physical characteristics to its behavior, diet, and more, it is evident that the Liopleurodon was a formidable animal.

Although the Liopleurodon was a giant animal, it was not as big as the Australian giant Kronosaurus, which had a maximum length of 36 feet. There was no substantial evidence to support this claim, but the series’ producers used this outrageous size anyway.Also, like juvenile sharks, young Liopleurodon stayed in shallow waters with their mother until they were old enough to care for themselves. We know Halstead attributed the reconstruction to Liopleurodon in 1982 (Halstead 1982), so we can be reasonably confident the reconstruction was based on material regarded by him as Liopleurodon at that time, which would have included the lectotype of ‘ Stretosaurus‘. It would also make sense for Tarlo to use the ‘Stretham Pliosaur’ specimen in the Newman & Tarlo reconstruction for two other reasons. First, he described and was intimately familiar with it (Tarlo, 1957, 1959, 1960), and second, in Tarlo’s words, “The Streatham specimen is one of the most important Pliosaur[sic] skeletons to have come out of the Kimeridge [sic][and]…most of the post-cranial skeleton can be described” (Tarlo 1959, p. 41). And, of course, the specimen certainly fulfils the criterion of “other giant pliosaur remains” as stipulated by Newman and Tarlo.