Tuarangisaurus (Māori: tuarangi "ancient" + Greek: σαῦρος, romanized: sauros "lizard") is an extinctgenus of elasmosaurid known from New Zealand. The type and only known species is Tuarangisaurus keyesi, named by "Pont" Wiffen, Joan Wiffen and Bill Moisley in 1986.[1][2] The specific name honours Ian W. Keyes of the New Zealand Geological Survey.
Discovery
Restored skeleton of T. cabazai (now considered as an indeterminate aristonectine)
Tuarangisaurus is known from the holotypeNZGS CD425, a nearly complete skull and mandible, and from NZGS CD426, rear skull elements and nine anterior-most cervical vertebrae from the same individual. Some postcranial remains of juveniles were also provisionally attributed to Tuarangisaurus, with one specimen (NZGS CD427) containing at least thirty gastroliths.[1] It was on 20 March 1978 collected by amateur paleontologists from the Maungataniwha Sandstone Member of the Tahora Formation, dating to the upper Campanian to lower Maastrichtian stage of the Late Cretaceous.[2]
A second species, T. australis, was named in 2005;[3] however, it was moved to the genus Eromangasaurus in 2007, becoming the senior synonym of E. carinognathus.[4] Another species, T.? cabazai, was also placed in Tuarangisaurus by Gasparini, Salgado and Casadio in 2003; however, it was most recently reassigned to an indeterminate aristonectine.[5]
In 2017, a complete specimen (CM Zfr 115), originally belonging to Mauisaurus, has been reassigned to this genus.[6] In 2018, Otero and colleagues redescribed the juvenile specimen NZGS CD427 elucidating the ontogeny of this plesiosaur. The specimen had many features common with the holotype, but it differed in the orientation of the maxilla along with the number of teeth present in it.[7]
Description
Tuarangisaurus was a medium-sized plesiosaur, with a complete specimen (CM Zfr 115) measuring over 8 metres (26 ft) long.[8] The preserved skull measured about 37.0 cm (1 ft 2.6 in) long, and its total skull length is estimated to have been 37.5 cm (1 ft 2.8 in) long.[1] It can be distinguished from all other known elasmosaurids by a unique combination of characteristics as well as two otherwise unknown traits: the ectopterygoid has a long process directed towards the back, and a large boss of bone underneath. A stapes is present in the holotype; this bone was previously thought to be absent from elasmosaurids.[2][9]
Classification
Tuarangisaurus was initially assigned to the Elasmosauridae;[1] one study found it to be a close relative of Callawayasaurus.[10] A phylogenetic analysis of plesiosaurs run by O'Gorman and colleagues in 2016 reaffirmed that Tuarangisaurus was an elasmosaurid, but rejected a close relationship with Callawayasaurus. Its position within the Elasmosauridae according to this analysis is shown below.[2]
^ abcdWiffen, J.; Moisley, W.L. (1986). "Late Cretaceous reptiles (Families Elasmosauridae and Pliosauridae) from the Mangahouanga Stream, North Island, New Zealand". New Zealand Journal of Geology and Geophysics. 29 (2): 205–252. Bibcode:1986NZJGG..29..205W. doi:10.1080/00288306.1986.10427535.
^ abcdO'Gorman, J.P.; Otero, R.A.; Hiller, N.; Simes, J.; Terezow, M. (2016). "Redescription of Tuarangisaurus keyesi (Sauropterygia; Elasmosauridae), a key species from the uppermost Cretaceous of the Weddellian Province: Internal skull anatomy and phylogenetic position". Cretaceous Research. 71: 118–136. doi:10.1016/j.cretres.2016.11.014.
^Benjamin P. Kear (2007). "Taxonomic clarification of the Australian elasmosaurid genus Eromangasaurus, with reference to other austral elasmosaur taxa". Journal of Vertebrate Paleontology. 27 (1): 241–246. doi:10.1671/0272-4634(2007)27[241:TCOTAE]2.0.CO;2. S2CID86673814.
^O'Gorman, J.P.; Gasparini, Z.; Salgado, L. (2014). "Reappraisal of Tuarangisaurus? cabazai (Elasmosauridae, Plesiosauria) from the Upper Maastrichtian of northern Patagonia, Argentina". Cretaceous Research. 47: 39–47. Bibcode:2014CrRes..47...39O. doi:10.1016/j.cretres.2013.10.003. hdl:11336/37287.
^Otero, R.A.; O'Gorman, J.P.; Moisley, W.L.; Terezow, M.; Mckee, J. (2018). "A juvenile Tuarangisaurus keyesi Wiffen and Moisley, 1986 (Plesiosauria, Elasmosauridae) from the Upper Cretaceous of New Zealand, with Remarks on Its Skull Ontogeny". Cretaceous Research. 85: 214–231. Bibcode:2018CrRes..85..214O. doi:10.1016/j.cretres.2017.09.007. hdl:11336/99631.
^Carpenter, K. (1999). "Revision of North American elasmosaurs from the Cretaceous of the western interior". Paludicola. 2: 148–173.
^Kubo, T.; Mitchell, M.T.; Henderson, D.M. (2012). "Albertonectes vanderveldei, a new elasmosaur (Reptilia, Sauropterygia) from the Upper Cretaceous of Alberta". Journal of Vertebrate Paleontology. 32 (3): 557–572. Bibcode:2012JVPal..32..557K. doi:10.1080/02724634.2012.658124. S2CID129500470.
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