''Futabasaurus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

of plesiosaur from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

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, Japan. It was described and named in 2006, and was assigned to the family

Elasmosauridae Elasmosauridae is an extinct family of plesiosaurs, often called elasmosaurs. They had the longest necks of the plesiosaurs and existed from the Hauterivian to the Maastrichtian stages of the Cretaceous, and represented one of the two groups ...

. The genus contains one species, ''F. suzukii''.

Description

The size of ''Futabasaurus'' has been estimated within the range of in length and in body mass. 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

clavicle The clavicle, or collarbone, is a slender, S-shaped long bone approximately 6 inches (15 cm) long that serves as a strut between the shoulder blade and the sternum (breastbone). There are two clavicles, one on the left and one on the rig ...

s are fused, and the

anterior Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

edge is bent; the

humerus The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...

is relatively long; and the femora are slim and show prominent muscle scars.

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 The Tamayama Formation is a Santonian geologic formation in Japan. Dinosaur remains not referrable to the genus level are among the fossils that have been recovered from the formation.Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517- ...

, in the Futaba Group of

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, Japan. The rocks in which it were found date to the '' Inoceramus amakusensis'' zone of the early

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya (million years ago) and 83.6 ± 0.7 mya. ...

. The fossils were found by Tadashi Suzuki, then a high school student. Many of the bones of the

type specimen In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes the ...

show signs of apparent scavenging or predation by sharks. 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 is a Japan, Japanese multinational corporation headquartered in Minami-ku, Hamamatsu, Japan. Suzuki manufactures automobiles, motorcycles, All-terrain vehicle, all-terrain vehicles (ATVs), outboard motor, outboard marine engines, wheelchairs ...

. The name "Futabasaurus" has also been used for an unrelated

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

, also from the Late Cretaceous of Japan. However, this dinosaur was not officially named, and remains a ''

nomen nudum In taxonomy, a ''nomen nudum'' ('naked name'; plural ''nomina nuda'') is a designation which looks exactly like a scientific name of an organism, and may have originally been intended to be one, but it has not been published with an adequate des ...

''.

Classification

The following

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

shows the placement of ''Futabasaurus'' within Elasmosauridae following an analysis by Rodrigo A. Otero, 2016: Fossil of Futabasaurus suzukii 02

References

External links

''Futabasaurus'' at Dinosaurier-Web
(German) Late Cretaceous plesiosaurs Fossil taxa described in 2006 Plesiosaurs of Asia Extinct animals of Japan Elasmosaurids Fossils of Japan Sauropterygian genera Santonian life {{plesiosaur-stub

Description

Discovery and naming

Classification

See also

References

External links