Futabasaurus

Futabasaurus is a genus of plesiosaur from the Late Cretaceous of Fukushima, Japan. It was described and named in 2006, and was assigned to the family Elasmosauridae. The genus contains one species, F. suzukii.

Futabasaurus Temporal range: Late Cretaceous, Santonian PreꞒ Ꞓ O S D C P T J K Pg N ↓
Reconstructed skeleton at National Science Museum, Tokyo
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Superorder:	†Sauropterygia
Order:	†Plesiosauria
Family:	†Elasmosauridae
Genus:	†Futabasaurus Sato, Hasegawa & Manabe, 2006
Species:	†F. suzukii
Binomial name
†Futabasaurus suzukii Sato, Hasegawa & Manabe, 2006

Description

Cast of fossils of Futabasaurus suzukii exhibited at the National Museum of Nature and Science

The length of Futabasaurus has been estimated at 6.4–9.2 metres (21–30 ft),[1] and it weighed about 3–4 tonnes (3.0–3.9 LT). It can be distinguished from other elasmosaurids by the following characteristics: there is a long distance between the eye sockets and nostrils; the interclavicles and clavicles are fused, and the anterior edge is bent; the humerus is relatively long; and the femora are slim and show prominent muscle scars.[2]

Discovery and naming

Futabasaurus is the first elasmosaurid found in Japan. It was originally known as either "Wellesisaurus sudzuki" or "Futaba-ryu" before publication. The type specimen of Futabasaurus was found in the Irimazawa Member of the Tamayama Formation, in the Futaba Group of Fukushima Prefecture, Japan. The rocks in which it were found date to the Inoceramus amakusensis zone of the early Santonian. The fossils were found by Tadashi Suzuki, then a high school student.[2] Many of the bones of the type specimen show signs of apparent scavenging or predation by sharks.[2]

The genus Futabasaurus was named after the Futaba Group, in which it was discovered; the species name is derived from the family name of its discoverer, Suzuki.[2] The name "Futabasaurus" has also been used for an unrelated theropod dinosaur, also from the Late Cretaceous of Japan. However, this dinosaur was not officially named, and remains a nomen nudum.

Classification

Pre-2006 skeletal mount which is informally labelled as "Wellesisaurus sudzuki" (with a large stone containing crinoids and ammonites in the background)

The following cladogram shows the placement of Futabasaurus within Elasmosauridae following an analysis by Rodrigo A. Otero, 2016:[3]

Fossils

Elasmosauridae

Eromangasaurus carinognathus       Callawayasaurus colombiensis       Libonectes morgani         Tuarangisaurus keyesi     Thalassomedon haningtoni         CM Zfr 115       Hydrotherosaurus alexandrae     Futabasaurus suzukii         Aristonectinae   Kaiwhekea katiki       Alexandronectes zealandiensis       Morturneria seymourensis       Aristonectes parvidens     Aristonectes quiriquinensis           Elasmosaurinae   Terminonatator pointeixensis         Elasmosaurus platyurus     Albertonectes vanderveldei         Styxosaurus sp. (="Hydralmosaurus serpentinus")       Styxosaurus snowii     Styxosaurus browni

See also

• List of plesiosaur genera
• Timeline of plesiosaur research

References

1. 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.
2. Sato, Tamaki; Hasegawa, Yoshikazu; Manabe, Makoto (2006). "A new elasmosaurid plesiosaur from the Upper Cretaceous of Fukushima, Japan". Palaeontology. 49 (3): 467–484. doi:10.1111/j.1475-4983.2006.00554.x.
3. Otero, R. A. (2016). "Taxonomic reassessment of Hydralmosaurus as Styxosaurus: new insights on the elasmosaurid neck evolution throughout the Cretaceous". PeerJ. 4: e1777. doi:10.7717/peerj.1777. PMC 4806632. PMID 27019781.

External links

• Futabasaurus at Dinosaurier-Web (German)