Tuarangisaurus

Tuarangisaurus (Maori tuarangi "ancient" + Greek sauros "lizard") is an extinct genus of elasmosaurid known from New Zealand. The type and only known species is Tuarangisaurus keyesi, named by Wiffen and Moisley in 1986.[1][2]

Tuarangisaurus Temporal range: Late Cretaceous, 78 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Restored skeleton
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Superorder:	†Sauropterygia
Order:	†Plesiosauria
Family:	†Elasmosauridae
Genus:	†Tuarangisaurus Wiffen & Moisley, 1986
Species:	†T. keyesi
Binomial name
†Tuarangisaurus keyesi Wiffen & Moisley, 1986

Description

The estimated length of Tuarangisaurus is about 8 metres (26 ft).[3] 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][4]

Discovery and naming

Tuarangisaurus is known from the holotype NZGS CD425, a nearly complete skull and mandible, and from NZGS CD426, nine anterior-most cervical vertebrae. Some postcranial remains of juveniles were also attributed to Tuarangisaurus.[1] It was collected from the Maungataniwha Sandstone Member of the Tahora Formation, dating to the upper Campanian to lower Maastrichtian stage of the Late Cretaceous, about 78 million years ago.[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.[5] A third species, T.? cabazai, was also referred to Tuarangisaurus by the original description;[1] however, it was most recently reassigned to an indeterminate aristonectine.[6]

Classification

Tuarangisaurus was initially assigned to the Elasmosauridae;[1] one study found it to be a close relative of Callawayasaurus.[7] A new phylogenetic analysis of plesiosaurs 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]

Elasmosauridae

Gronausaurus       Speeton clay plesiosaur       Wapuskanectes betsynicollsae       Callawayasaurus colombiensis         Styxosaurus snowii     Futabasaurus suzukii           Albertonectes vanderveldei     Tuarangisaurus keyesi     Thalassomedon haningtoni     Elasmosaurus platyurus         Terminonatator ponteixensis       Hydrotherosaurus alexandrae       Libonectes morgani       Kawanectes lafquenianum     Vegasaurus molyi     Morenosaurus stocki       Kaiwhekea katiki     Aristonectes parvidens     Aristonectes quiriquinensis

See also

• List of plesiosaur genera
• Timeline of plesiosaur research

References

1. Wiffen, 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. doi:10.1080/00288306.1986.10427535.
2. O'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.
3. Sachs, S. (2005). "Tuarangisaurus australis sp. nov. (Plesiosauria: Elasmosauridae) from the Lower Cretaceous of northeastern Queensland, with additional notes on the phylogeny of the Elasmosauridae" (PDF). Memoirs of the Queensland Museum. 50 (2): 425–440. Archived from the original (PDF) on 2011-09-28.
4. Carpenter, K. (1999). "Revision of North American elasmosaurs from the Cretaceous of the western interior". Paludicola. 2: 148–173.
5. 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.CS1 maint: uses authors parameter (link)
6. 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. doi:10.1016/j.cretres.2013.10.003.
7. 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. doi:10.1080/02724634.2012.658124.