| Tuarangisaurus | |
|---|---|
 | |
| Life restoration ofT. keyesi | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Superorder: | †Sauropterygia |
| Order: | †Plesiosauria |
| Superfamily: | †Plesiosauroidea |
| Family: | †Elasmosauridae |
| Genus: | †Tuarangisaurus Wiffen,Wiffen & Moisley,1986 |
| Species: | †T. keyesi |
| Binomial name | |
| †Tuarangisaurus keyesi Wiffen, Wiffen & Moisley, 1986 | |
Tuarangisaurus (Māori:tuarangi "ancient" +Greek:σαῦρος,romanized: sauros "lizard") is anextinctgenus ofelasmosaurid known fromNew Zealand. Thetype and only known species isTuarangisaurus keyesi, named by "Pont" Wiffen,Joan Wiffen and Bill Moisley in1986.[1][2] The specific name honours Ian W. Keyes of the New Zealand Geological Survey.
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Tuarangisaurus is known from theholotypeNZGS CD425, a nearly completeskull andmandible, and from NZGS CD426, rear skull elements and nine anterior-mostcervical vertebrae from the same individual. Somepostcranial remains of juveniles were also provisionally attributed toTuarangisaurus, 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 theTahora Formation, dating to the upperCampanian to lowerMaastrichtian stage of theLate Cretaceous.[2]
A second species,T. australis, was named in 2005;[3] however, it was moved to the genusEromangasaurus in 2007, becoming the senior synonym ofE. carinognathus.[4] Another species,T.? cabazai, was collected during the early 2000s and was also placed inTuarangisaurus by Gasparini, Salgado and Casadio in 2003; however, it was most recently reassigned to an indeterminatearistonectine.[5]
In 2017, a complete specimen (CM Zfr 115), originally belonging toMauisaurus, 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]
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. Astapes is present in the holotype; this bone was previously thought to be absent from elasmosaurids.[2][9]
Tuarangisaurus was initially assigned to theElasmosauridae;[1] one study found it to be a close relative ofCallawayasaurus.[10] A phylogenetic analysis of plesiosaurs run by O'Gorman and colleagues in 2016 reaffirmed thatTuarangisaurus was anelasmosaurid, but rejected a close relationship withCallawayasaurus. Its position within the Elasmosauridae according to this analysis is shown below.[2]
| Elasmosauridae |
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