Kingdom Animalia Superorder †Sauropterygia Species †T. keyesi Rank Genus | Class Reptilia Family †Elasmosauridae Phylum Chordata Order Plesiosauria | |
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Similar Plesiosauria, Terminonatator, Kaiwhekea, Eromangasaurus, Callawayasaurus | ||
Tuarangisaurus (Maori tuarangi "ancient" + Greek sauros "lizard") is an extinct genus of elasmosaurid known from New Zealand. The type and only known species is T. keyesi, named by Wiffen and Moisley in 1986.
Contents
Description
The estimated length of Tuarangisaurus is about 8 metres (26 ft). 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.
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. 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.
A second species, T. australis, was named in 2005; however, it was moved to the genus Eromangasaurus in 2007, becoming the senior synonym of E. carinognathus. A third species, T.? cabazai, was also referred to Tuarangisaurus by the original description; however, it was most recently reassigned to an indeterminate aristonectine.
Classification
Tuarangisaurus was initially assigned to the Elasmosauridae; one study found it to be a close relative of Callawayasaurus. 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.