Pliosaurus
Pliosaurus | |
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P. kevani holotype skull | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Superorder: | †Sauropterygia |
Order: | †Plesiosauria |
Family: | †Pliosauridae |
Clade: | †Thalassophonea |
Genus: | †Pliosaurus Owen, 1842 |
Type species | |
†Pliosaurus brachydeirus Owen, 1842
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Species[1][2] | |
Species pending reassessment
Species pending ICZN petition
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Synonyms | |
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Pliosaurus (meaning 'more lizard') is an
Discovery and Species
Pliosaurus brachydeirus
Pliosaurus brachydeirus is the
P. brachydeirus is known from the
Knutsen (2012) revised the validity of this species and was able to diagnose it on a basis of combination of traits. P. brachydeirus had approximately 70 teeth in the lower jaw (72 according to Benson et al. (2013)), 8-9 or more pairs of symphyseal teeth in dorsal view (12 pairs according to Benson et al. (2013)) and 5 or more
Pliosaurus carpenteri
P. carpenteri is known solely from the
Sassoon et al. (2012) originally ascribed the differences between BRSMG Cc332 (the holotype of P. westburyensis) and BRSMG Cd6172 to intraspecific variation, with these specimens possibly being sexual dimorphs, due to fact that both were collected from close stratigraphic levels of the same quarry.[11] However, Benson et al. (2013) showed that the differences between them are relatively great even in the context of specimens from other localities. They diagnosed P. carpenteri based on a single autapomorphy – unlike all other thalassophoneans other than the proposed neotype of P. brachyspondylus, the dorsal surface of the surangular lacks any fossa, and in contrast to all other specimens of Pliosaurus faces dorsally, not inclined to face dorsolaterally. P. carpenteri also possesses a unique combination of characters, including: low dentary alveolar count including only 18 postsymphysial alveoli, and a total count of 27; intermediate low count of syphysial alveoli including only 9; teeth fully trihedral, possessing a flat, anteroposteriorly broad labial surface lacking enamel ridges; mediolateral expansion of caniniform regions of the premaxilla and maxilla relatively pronounced, although this might be due to crushing; six closely spaced premaxillary alveoli; anisodont premaxillary dentition; diastema present between maxillary and premaxillary alveolar rows; premaxilla–parietal suture located level with the anterior region of the orbit; cervical centra lacking ventral ridge; and epipodials with highly convex proximal surfaces.[1]
Pliosaurus funkei
P. funkei is known from two partial skeletons, the
The holotype of P. funkei is represented by the anterior portions of the upper and lower jaws (including
Knutsen et al. (2012) diagnosed the species based on a unique combination of characters of the holotype. P. funkei has a possibly unique "type I" retroarticular process, unlike P. brachydeirus, P. brachyspondylus and P. macromerus. Unlike P. brachydeirus, its cervical centra possess a rugose ventral surface, but lack ventral keel. Finally, it possesses comparatively longer forelimbs than other known pliosaurids, with a long humerus, more than 7 times the average width of cervical vertebral centra, in comparison to P. brachyspondylus and P. rossicus, which have humeri less than 4.5 times the cervical width. Its complete teeth count is not known, however, it has at least six pairs of teeth in the mandibular symphysis, and at least five premaxillary tooth pairs. The two known individuals of P. funkei preserve mostly different regions of the skeleton and overlap only by cervical vertebrae. Nevertheless, these cervical vertebrae are morphologically indistinguishable, and both individuals were found in proximity to one another, at exactly the same stratigraphic horizon of the Slottsmøya member, strongly supporting the referral of PMO 214.136 to P. funkei. Knutsen et al. (2012) suggested that P. funkei is more similar to P. rossicus and the proposed neotype of P. macromerus than to P. brachydeirus and the proposed neotype of P. brachyspondylus in its cranial morphology.[5]
Analysis of bones from the four flippers suggest that the animal cruised using only the fore-flippers, using the back flippers for extra speed when pursuing and capturing prey.
Predator X's brain was of a similar type and size, proportionally, to that of today's great white shark, the team says.[15]
A television programme entitled
Pliosaurus kevani
P. kevani is known solely from the
Benson et al. (2013) diagnosed the species based on four
CAMSM J.35990, a complete
Pliosaurus rossicus
P. rossicus was first described and named by
Halstead (1971) referred a second, larger specimen PIN 2440/1 consisting of a partial rostrum and hind limb, to P. rossicus.[19] PIN 2440/1 was originally described as Pliosaurus cf. grandis by Rozhdestvenskii (1947), but later referred to P. rossicus based on the presence of a similar number of mandibular symphyseal teeth with the holotye and their relative stratigraphic co-occurrence. Another specimen of large pliosaur was tentatively assigned to P. rossicus by Malakhov (1999). The specimen was collected from the lower Volgian (early Tithonian) of Kazakhstan, and represents postcranial remains No. 13-1958, at Institute of Zoology MS-AS RK.[2]
Knutsen (2012) suggested possible synonymy between P. macromerus and P. rossicus based on the presence of only six symphysial and five premaxillary alveoli in both. Nevertheless, he provisionally retained P. rossicus as a separate species, as the stratigraphic ranges of the two taxa do not overlap, and the specimens were not adequate described.[2] However, a reexamination of NHMUK PV OR 39362 (proposed neotype of P. macromerus) by Benson et al. (2013), revealed that it had at least seven symphyseal tooth, but more likely nine. Therefore, they considered P. rossicus to be a valid species of Pliosaurus based on the presence of an autapomorphic short symphysis containing only six alveoli. Based on the presence of this trait, they tentatively referred OUMNH J.10454 (and thus possibly OUMNH J.50376 and OUMNH J.50377) to P. ? rossicus.[1] These specimens were all collected at Chawley brick pit, of the upper part of the Lower Kimmeridge Clay, dating to the late Kimmeridgian, and were originally assigned to P. macromerus.[2] OXFUM J.10454 is a highly reconstructed and fragmentary specimen, with a total length of 287.5 cm (9.43 ft). Tarlo estimated that the skull length of this individual had originally been more than 3 m (9.8 ft),[20] however Benson et al. (2013) argued that this cannot be currently determined. Apart from the autapomorphy noted above[1] and trihedral teeth, P. rossicus possesses the following combination of characters (based on its holotype): 5 premaxillary tooth pairs; cervical vertebrae with ornamented ventral surface, but lacking ventral keel; proportionally shorter humeri than P. funkei, less than 4.5 times the average width of cervical centra, versus more than 7 times.[2]
Pliosaurus westburyensis
P. westburyensis is known solely from the
The mandible of BRSMG Cc332 is approximately 50 cm longer than CAMSM J.35991 (proposed neotype for P. brachyspondylus), but is shorter than the two French specimens referred to P. brachyspondylus. Knutsen (2012) distinguished BRSMG Cc332 from P. brachyspondylus as the former has a "type IV" retroarticular process and a much lower degree of fusion between the anterior mandibular bones.
Other species
Pliosaurus brachyspondylus
Pliosaurus brachyspondylus was first described and named by Owen in 1839, as a species of Plesiosaurus. The specific name is derived from βραχυς, brachus, meaning "short" and σπόνδυλος, spondylos, meaning "vertebra" in Ancient Greek.[22] It was named on the basis of a series of unassociated cervical vertebrae as the holotype. These specimens were collected at Headington Pits near Oxford, Oxfordshire, England, from the Kimmeridge Clay. It was later noted by Pocock (1908), that the material was found in the lower part of the Kimmeridge Clay, as the pits expose the contact between the Kimmeridge Clay Formation and the underlying Corallian beds. Several other cervical centra from the same strata at Weymouth, Dorsetshire, that had been named Plesiosaurus giganteus by Conybeare (1824), were also referred to Plesiosaurus brachyspondylus by Owen (1839). Eichwald (1868) reassigned P. brachyspondylus to Pliosaurus but did not provide diagnosis to distinguish these vertebrae from those of the type species of the genus. P. giganteus was later synonymised by Lydekker (1889a) with P. brachydeirus, the type species.[2]
According to Tarlo (1959a), the holotypes of P. giganteus and P. brachyspondylus have been lost or destroyed since their initial descriptions.
In the same paper, Tarlo (1959a) described an associated pliosaur skeleton, CAMSM J.35991, and referred it to P. brachyspondylus.[23] CAMSM J.35991 consists of a complete mandible, most of the axial skeleton and parts of the appendicular skeleton. It was found in 1889 in the Aulacostephanus eudoxus ammonite zone of the lower Kimmeridge Clay, at the same locality as CAMSM J.29564 (the neotype for P. brachyspondylus). Knutsen (2012) suggested to replace the neotype for P. brachyspondylus, with CAMSM J.35991 as the new neotype, because both specimens and possibly the lost holotype are from the same locality and horizon, and similar in size. CAMSM J.35991 is much more complete and can be distinguished from all other species of Pliosaurus.[2] Benson et al. (2013) agreed with this suggestion, but considered P. brachyspondylus to be Thalassophonea indet., until a petition to the ICZN is made.[1] Based on CAMSM J.35991, Knutsen (2012) provisionally diagnosed P. brachyspondylus as a Pliosaurus with approximately 60 (58 according to Benson et al. (2013)) teeth in the lower jaw, 9 pairs of symphyseal teeth in dorsal view. It had "type II" retroarticular process and proportionally shorter humeri than P. funkei. As also seen in CAMSM J.29564, it had cervical centra with ventral surface ornamentation, but lacking a ventral keel. According to Benson et al. (2013), the flat morphology of the proximal surface of the radius or tibia suggests that CAMSM J.35991 is a juvenile.[2][1]
According to Knutsen (2012), Bardet et al. (1993) referred two additional
Pliosaurus macromerus
Pliosaurus macromerus was first described and named by
Tarlo (1959b) erected OUMNH J. 10441, one of the partial cervical vertebrae from the collection of unassociated remains listed by Philips (1871), as the
Based on similar number of mandibular symphyseal teeth with NHMUK PV OR 39362, Tarlo (1959b) also assigned to S. macromerus a partial
Knutsen (2012) suggested to replace the lectotype of P. macromerus, with NHMUK PV OR 39362 as a
Other specimens previously referred to P. macromerus are currently assigned to other species of Pliosaurus, rendering this species a
Pliosaurus irgisensis
P. irgisensis was first described and named by
Pliosaurus portentificus
Pliosaurus portentificus is known from the late Kimmeridgian of England. Considered by Knutsen (2012) and Benson et al. (2013) to be undiagnostic, with its holotype specimen most likely being a juvenile individual of one of the other species of Pliosaurus.[2][1]
Description
Using Liopleurodon, another large pliosaurid, as a guide, a specimen found in the Svalbard islands of northern Europe has been estimated to have been 15 metres (49 ft) long, 45 metric tons (50 short tons) in body mass and had teeth 30 centimetres (12 in) long.[25][15] It is estimated to have lived approximately 147 million years ago.[26] Later on, thorough scrutiny of this Svalbard specimen revealed that it was not as massive as originally claimed; total length estimates have been revised to 10–13 metres (33–43 ft)[5] and was named Pliosaurus funkei in Knutsen et al. (2012), with estimated skull lengths of 1.6–2 m (5.2–6.6 ft) and a forelimb length of 3 m (9.8 ft) for the holotype (PMO 214.135), and an estimated skull length of 2–2.5 m (6.6–8.2 ft) for the referred specimen (PMO 214.136), suggesting that the animal had proportionally bigger flippers than other pliosaurs compared to the skull size and dimensions of the vertebrae.[5] Other species, such as P. carpentri, was about 8 metres (26 ft) long and weighed 5 metric tons (5.5 short tons), while P. rossicus was about 10 metres (33 ft) long and weighed 11 metric tons (12 short tons).[27][28][4] Some specimens may even be 11.7–14.4 metres (38–47 ft) long and are based on a giant mandible and giant neck vertebrae that may be referred to Pliosaurus.[6][1] Analysis of bones from the four flippers suggest that the animal cruised using just two fore-flippers, using the back pair for extra speed when pursuing and capturing prey. P. funkei brain was of a similar type and size, proportionally, to that of today's great white shark.[15][5] In 2014, Foffa and colleagues estimated the bite force of P. kevani which produced varying results from 9,617–16,927 N (981–1,726 kgf; 2,162–3,805 lbf) at the anterior dentary tooth to 27,685–48,728 N (2,823–4,969 kgf; 6,224–10,954 lbf) at the 36th dentary tooth pair.[29]
Phylogeny
The cladogram below follows a 2013 analysis by paleontologists Benson et al.[1]
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See also
References
- ^ PMID 23741520.
- ^ ISSN 0029-196X. Low resolution pdf Archived 2013-12-24 at the Wayback Machine High resolution pdf Archived 2013-12-24 at the Wayback Machine
- S2CID 130194647.
- ^ ISBN 978-0-691-19380-9.
- ^ ISSN 0029-196X. Low resolution pdf
- ^ S2CID 258630597.
- ISBN 978-1-77085-049-1.
- ^ .
- ^ a b c Owen, Richard (1841). "Odontography". London: Hippolyte Bailliere: 655 pp.
- ^ a b Owen, Richard (1841). "Report on British fossil reptiles, part 2". Report of the Eleventh Meeting for the British Association for the Advancement of Science, Plymouth. 11: 60–204.
- ^ .
- Cosmos Magazine. 2009-03-31. Archived from the originalon 2009-03-27. Retrieved 2013-10-22.
- ^ "Arctic sea monster's giant bite". BBC. 2009-03-17. Retrieved 2009-03-17.
- ^ Smith, Lewis (2009-03-17). "Predator X was the most fearsome animal ever to swim the oceans". The Times. London. Retrieved 2009-03-17.
- ^ a b c Coghlan, Andy (2009-03-17). "Fossil of 'ultimate predator' unearthed in Arctic". New Scientist. Retrieved 2009-03-17.
- ^ "Predator X". Planet Dinosaur. BBC. Retrieved 9 May 2012.
- ^ Novozhilov, N.I. (1948). "Two new pliosaurs from the Lower Volga Beds Provolzhe (Right bank of Volga)". Doklady Akademii Nauk SSSR. 60: 115–118.
- ^ Novozhilov, N.I. (1964). "Order Sauropterygia". Osnovy Paleontologii. 12: 309–332.
- ^ a b Halstead, L. Beverly (1971). "Liopleurodon rossicus (Novozhilov) - a pliosaur from the Lower Volgian of the Moscow basin" (PDF). Palaeontology. 14: 566–570.
- ^ a b c d Tarlo, Lambert Beverly (1959). "Stretosaurus gen. nov., a giant pliosaur from the Kimmeridge Clay". Palaeontology. 2: 39–55.
- ^ S2CID 85378579.
- ^ Owen, Richard (1839). "Report on British fossil reptiles, part 1". Report of the Ninth Meeting for the British Association for the Advancement of Science, Birmingham. 9: 43–126.
- ^ a b Tarlo, Lambert Beverly (1959). "Pliosaurus brachyspondylus (Owen) from the Kimmeridge Clay". Palaeontology. 1: 283–291.
- .
- ^ Alleyne, Richard (2009-03-17). "Biggest and smallest prehistoric predators unearthed". The Daily Telegraph. London. Archived from the original on 2009-03-20. Retrieved 2009-03-17.
- ^ "Fossil 'makes T-Rex look feeble'" Archived 2009-03-21 at the Wayback Machine, news24.com, 17 March 2009.
- ^ Larkin, N.; Dey, S. (2021). "Mounting the Type specimen of Pliosaurus carpenteri, an 8m-long fossil pliosaur (extinct marine reptile) skeleton for Bristol City Museum, including the 3D printed 2m-long skull". Retrieved January 25, 2023.
- ISBN 978-0-521-54582-2.
- PMID 24925465.
External links
- Media related to Pliosaurus at Wikimedia Commons
- https://www.reuters.com/article/scienceNews/idUSL2771508220080227?pageNumber=2&virtualBrandChannel=0
- Gigantic Pliosaurus discovered on Norwegian soil
- Pliosaurus - Naturhistorisk museum
- Sea Monsters: A Prehistoric Adventure Movie - Interactive Time Line - National Geographic
- Britannica Online Encyclopedia
- BBC Earth (video): The most powerful marine reptile ever
- NATURE Attenborough and the Jurassic Sea Monster (PBS video)