''Futabasaurus'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

plesiosaur The Plesiosauria or plesiosaurs are an Order (biology), order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared in the latest Triassic Period (geology), Period, possibly in the Rhaetian st ...

from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent 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 ''cre ...

of Fukushima,

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

. It was described and named in

2006 2006 was designated as the International Year of Deserts and Desertification. Events January * January 1– 4 – Russia temporarily cuts shipment of natural gas to Ukraine during a price dispute. * January 12 – A stampede during t ...

, and was assigned to the family

Elasmosauridae Elasmosauridae, often called elasmosaurs or elasmosaurids, is an extinct family of plesiosaurs that lived from the Hauterivian stage of the Early Cretaceous to the Maastrichtian stage of the Late Cretaceous period (c. 130 to 66 mya). The taxo ...

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

Description

''Futabasaurus'' has been estimated over in length, possibly within the range of . It can be distinguished from other elasmosaurids by the following characteristics: there is a long distance between the eye sockets and nostrils; the

interclavicle An interclavicle is a bone which, in most tetrapods, is located between the clavicles. Therian mammals ( marsupials and placentals) are the only tetrapods which never have an interclavicle, although some members of other groups also lack one. In ...

s and

clavicle The clavicle, collarbone, or keybone is a slender, S-shaped long bone approximately long that serves as a strut between the scapula, shoulder blade and the sternum (breastbone). There are two clavicles, one on each side of the body. The clavic ...

s are fused, and the

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

edge is bent; the

humerus The humerus (; : humeri) 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 (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...

is relatively long; and the

femora The femur (; : femurs or femora ), or thigh bone is the only bone in the thigh — the region of the lower limb between the hip and the knee. In many four-legged animals the femur is the upper bone of the hindleg. The top of the femur fits in ...

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 Coniacian-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." P ...

, in the Futaba Group of

Fukushima Prefecture is a Prefectures of Japan, prefecture of Japan located in the Tōhoku region of Honshu. Fukushima Prefecture has a population of 1,771,100 () and has a geographic area of . Fukushima Prefecture borders Miyagi Prefecture and Yamagata Prefecture ...

. 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 m ...

. 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 wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...

show signs of apparent scavenging or predation by sharks, specifically ''

Cretalamna ''Cretalamna'' is a genus of extinction, extinct Otodontidae, otodontid shark that lived from the latest Early Cretaceous to Eocene epoch (about 103 to 46 million years ago). It is considered by many to be the ancestor of the largest sharks to ha ...

''. The genus ''Futabasaurus'' was named after the Futaba Group, in which it was discovered; the specific name is derived from the family name of its discoverer,

Suzuki is a Japanese multinational mobility manufacturer headquartered in Hamamatsu, Shizuoka Prefecture, Shizuoka. It manufactures automobiles, motorcycles, all-terrain vehicles (ATVs), outboard motor, outboard marine engines, wheelchairs and a va ...

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

theropod Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...

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

, from the

Ashizawa Formation The Ashizawa Formation is a Coniacian geologic formation in northeastern Honshu, Japan. Dinosaur remains are among the fossils that have been recovered from the formation, although none have yet been referred to a specific genus.Weishampel, et a ...

. However, this dinosaur was not officially named, and remains a ''

nomen nudum In Taxonomy (biology), 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 ...

''.

Classification

The following

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

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

References

External links

''Futabasaurus'' at Dinosaurier-Web
(German) {{Taxonbar, from=Q141642 Late Cretaceous plesiosaurs Fossil taxa described in 2006 Plesiosaurs of Asia Extinct animals of Japan Elasmosauridae Fossils of Japan Sauropterygian genera Santonian life

Description

Discovery and naming

Classification

See also

References

External links