Biology:Tuarangisaurus

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Tuarangisaurus (Māori: tuarangi "ancient" + Greek: σαῦρος, romanized: sauros "lizard") is an extinct genus of elasmosaurid known from New Zealand and Argentina. The type and only known species is Tuarangisaurus keyesi, named by "Pont" Wiffen, Joan Wiffen and Bill Moisley in 1986. 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 holotype NZGS 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 collected during the early 2000s and 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] In 2026, O'Gorman, Scasso and Medina assigned an elasmosaurid specimen MPEF-PV 12001 from the Lefipán Formation of Argentina to T. keyesi.[8]

Description

Tuarangisaurus was a medium-sized plesiosaur, with a complete specimen (CM Zfr 115) measuring over 8 metres (26 ft) long.[9] 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][10]

Classification

Tuarangisaurus was initially assigned to the Elasmosauridae;[1] one study found it to be a close relative of Callawayasaurus.[11] 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]

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

References

  1. ↑ 1.0 1.1 1.2 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. Bibcode: 1986NZJGG..29..205W. 
  2. ↑ 2.0 2.1 2.2 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". Memoirs of the Queensland Museum 50 (2): 425–440. http://www.plesiosaur.com/database/pdf/sachs_2005.pdf. 
  4. ↑ 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:TCOTAE2.0.CO;2]. 
  5. ↑ 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. Bibcode: 2014CrRes..47...39O. 
  6. ↑ Hiller, Norton; O'Gorman, José P.; Otero, Rodrigo A.; Mannering, Al A. (2017). "A reappraisal of the Late Cretaceous Weddellian plesiosaur genus Mauisaurus Hector, 1874". New Zealand Journal of Geology and Geophysics 60 (2): 112–128. doi:10.1080/00288306.2017.1281317. Bibcode: 2017NZJGG..60..112H. https://www.researchgate.net/publication/313487910. 
  7. ↑ 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. doi:10.1016/j.cretres.2017.09.007. Bibcode: 2018CrRes..85..214O. 
  8. ↑ O'Gorman, J. P.; Scasso, R. A.; Medina, F. A. (2026). "The first record of Tuarangisaurus (Sauropterygia, Plesiosauria) from the Maastrichtian of the Lefipán Formation, Chubut, Argentina". Palaeontologia Electronica 29 (2). doi:10.26879/1531. 
  9. ↑ O'Gorman, J.P. (2016). "A Small Body Sized Non-Aristonectine Elasmosaurid (Sauropterygia, Plesiosauria) from the Late Cretaceous of Patagonia with Comments on the Relationships of the Patagonian and Antarctic Elasmosaurids". Ameghiniana 53 (3): 245–268. doi:10.5710/AMGH.29.11.2015.2928. http://sedici.unlp.edu.ar/handle/10915/108247. 
  10. ↑ Carpenter, K. (1999). "Revision of North American elasmosaurs from the Cretaceous of the western interior". Paludicola 2: 148–173. 
  11. ↑ 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. Bibcode: 2012JVPal..32..557K. 

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