''Fukuititan'' (meaning "giant from

Fukui prefecture is a Prefectures of Japan, prefecture of Japan located in the Chūbu region of Honshū. Fukui Prefecture has a population of 737,229 (1 January 2025) and has a geographic area of 4,190 Square kilometre, km2 (1,617 sq mi). Fukui Prefecture border ...

") 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 ...

sauropod Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their b ...

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 ...

that lived during the

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

(either

Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 125.77 Ma (million years ago) and 121.4 ± 1.0 Ma (Historically, this stage was placed at 129.4 million to approximately 125 million years ago) It is a ...

Aptian The Aptian is an age (geology), age in the geologic timescale or a stage (stratigraphy), stage in the stratigraphic column. It is a subdivision of the Early Cretaceous, Early or Lower Cretaceous epoch (geology), Epoch or series (stratigraphy), S ...

age) in the

Kitadani Formation The Kitadani Formation ( ''Kitadani-sō'') is a unit of Lower Cretaceous sedimentary rock which crops out near the city of Katsuyama in Fukui Prefecture, Japan, and it is the primary source of Cretaceous-aged non-marine vertebrate fossils in Jap ...

in what is now

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 ...

. The genus contains a single species, ''Fukuititan nipponensis''. The discovery of ''Fukuititan'' shed light on Japanese titanosauriforms, which are generally very poorly-known.

Discovery and naming

The fossils that would eventually be named ''Fukuititan'' were discovered in the summer of 2007 at the Kitadani Dinosaur Quarry, near the Sugiyama River, by an expedition in association with the Fukui Prefectural Dinosaur Museum, which is where the specimen would eventually be reposited. The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

and only specimen of ''Fukuititan'', given the specimen number FPDM-V8468, was described in

2010 The year saw a multitude of natural and environmental disasters such as the 2010 Haiti earthquake, the Deepwater Horizon oil spill, and the 2010 Chile earthquake. The 2009 swine flu pandemic, swine flu pandemic which began the previous year ...

by Japanese scientists Yoichi Azuma and Masateru Shibata, who were working for the museum in which it was stored. It was given the species epithet ''"nipponensis"'', which means "from

Description

''Fukuititan'' was a medium-sized sauropod. The authors of its description did not give a precise estimate of its size, but subsequent authors have suggested a full length of long, a height of tall at the shoulder, and a mass of 5.75 tons.

Gregory S. Paul Gregory Scott Paul (born December 24, 1954) is an American freelance researcher, author and illustrator who works in paleontology. He is best known for his work and research on theropoda, theropod dinosaurs and his detailed illustrations, both l ...

later suggested that the

of ''Fukuititan'' represents an immature individual, and therefore no concrete estimates of its adult size can be made. The holotype specimen was discovered within an area of . In spite of this being a relatively large area, the lack of repeated elements led Azuma and Shibata to infer that all of the remains represent a single individual. The elements known include two partial

cervical vertebra In tetrapods, cervical vertebrae (: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In sauropsid s ...

e, three vertebrae from the end of the tail, part of the left

scapula The scapula (: scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side ...

, both

humeri 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 and ulna, and consists of three sections. The humeral upper extremity consists of ...

, both

radii In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is the line segment or ...

, a right

metacarpal In human anatomy, the metacarpal bones or metacarpus, also known as the "palm bones", are the appendicular bones that form the intermediate part of the hand between the phalanges (fingers) and the carpal bones ( wrist bones), which articulate ...

, both

ischia Ischia ( , , ) is a volcanic island in the Tyrrhenian Sea. It lies at the northern end of the Gulf of Naples, about from the city of Naples. It is the largest of the Phlegrean Islands. Although inhabited since the Bronze Age, as a Ancient G ...

, a partial right

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

and

tibia The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outsi ...

, the left

fibula The fibula (: fibulae or fibulas) or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. ...

, a single toe bone, three teeth, and several indeterminate bone fragments. ''Fukuititan'' can be distinguished from all other titanosauriformes by the presence of a stalk-like of the cervical vertebrae, a relatively wide humerus, metacarpals about half the length of the radius, and several features of the teeth.

Classification

The lack of any remains from the

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

ribs The rib cage or thoracic cage is an endoskeletal enclosure in the thorax of most vertebrates that comprises the ribs, vertebral column and sternum, which protect the vital organs of the thoracic cavity, such as the heart, lungs and great vessels ...

of ''Fukuititan'' makes its affinities somewhat difficult to determine. Features of the

caudal vertebra Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...

e and the co-ossification of the

lend support to its inclusion within

Titanosauriformes Macronaria is a clade of sauropod dinosaurs. Macronarians are named after the large diameter of the nasal opening of their skull, known as the external naris, which exceeded the size of the orbit, the skull opening where the eye is located (hence ...

. However, when they described ''Fukuititan'', Azuma and Shibata remarked that a more specific phylogenetic placement was impossible to assign based on the incompleteness of the remains. Some subsequent analyses have omitted ''Fukuititan'' from their

phylogenetic analyses In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as Computational phylogenetics, phylogenetic inference. It infers the relationship among organ ...

because its incomplete nature makes its placement unstable. Other authors have suggested that it is closely related to '' Tastavinsaurus'' and its relatives. An abbreviated cladogram from a 2024 analysis by Yang F. Han and colleagues is shown below.

References

{{Taxonbar, from=Q2096199 Macronaria Dinosaur genera Aptian dinosaurs Fossil taxa described in 2010 Dinosaurs of Japan

Discovery and naming

Description

Classification

See also

References