''Kamuysaurus'' 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 ...

of herbivorous edmontosaurin

saurolophine Saurolophinae is a subfamily (biology), subfamily of hadrosaurid dinosaurs. It has since the mid-20th century generally been called the Hadrosaurinae, a group of largely non-crested hadrosaurs related to the crested sub-family Lambeosaurinae. How ...

hadrosaurid Hadrosaurids (), also hadrosaurs or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod fami ...

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

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 ...

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

marine deposits of the

Yezo Group The Yezo Group is a stratigraphic group in Hokkaido, Japan and Sakhalin, Russia which is primarily Late Cretaceous in age (Aptian to Earliest Paleocene). It is exposed as roughly north–south trending belt extending 1,500 kilometres through centr ...

( Hakobuchi Formation) in the Hobetsu area near the town of Mukawa,

Hokkaido is the list of islands of Japan by area, second-largest island of Japan and comprises the largest and northernmost prefectures of Japan, prefecture, making up its own list of regions of Japan, region. The Tsugaru Strait separates Hokkaidō fr ...

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 ...

Discovery

In 2003, amateur paleontologist Yoshiyuki Horita at the Shirafunezawa Creek discovered the tail of a euornithopod. An entire skeleton was in 2013 and 2014 uncovered by teams of the Hobetsu Museum and the Hokkaido University Museum. The find was nicknamed ''Mukawaryu'', the "Dragon of Mukawa". In 2019, the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

''Kamuysaurus japonicus'' was named and described by Professor

Yoshitsugu Kobayashi Yoshitsugu Kobayashi (小林快次, ''Kobayashi Yoshitsugu'', born 1971) is a Japanese vertebrate paleontologist. He is a professor and the assistant director in Hokkaido University Museum. His major achievements include the description and nami ...

, Tomohiro Nishimura, Ryuji Takasaki, Kentaro Chiba, Anthony Ricardo Fiorillo, Kohei Tanaka, Tsogtbaatar Chinzorig, Tamaki Sato and Kazuhiko Sakurai. The generic name is derived from ''

kamuy A ''kamuy'' (; ) is a spiritual or divine being in Ainu mythology, a term denoting a supernatural entity composed of or possessing spiritual energy. The Ainu people have many myths about the ''kamuy'', passed down through oral traditions and r ...

'', meaning "deity" in Ainu, the language of the original inhabitants of Hokkaido. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

''japonicus'', "japanese" in

Neo-Latin Neo-LatinSidwell, Keith ''Classical Latin-Medieval Latin-Neo Latin'' in ; others, throughout. (also known as New Latin and Modern Latin) is the style of written Latin used in original literary, scholarly, and scientific works, first in Italy d ...

, refers to the provenance from Japan. 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 ...

, HMG-1219, has been found in a marine layer of the Hakobuchi Formation, part of the

, dating from the early

, between 72.1 and 70.6 million years old. It consists of a nearly complete skeleton with skull, only missing the snout, parts of the sacral vertebrae and phalanges. Containing over 60% of the skeletal elements and 80% of the bone mass, it is, together with the smaller skeleton of ''

Fukuivenator ''Fukuivenator'' ("hunter of Fukui Prefecture") is an extinct genus of maniraptoran theropod dinosaur from the Early Cretaceous of Japan. Discovery and naming The type species ''Fukuivenator paradoxus'' was named and described in 2016 by Yoi ...

'', one of the most complete dinosaur skeletons found in Japan. The bones were found on a surface of and were partially articulated, though sometimes damaged by erosion. The holotype represents an adult individual of at least nine years of age. It was likely washed into the sea as a carcass.

Description

''Kamuysaurus'' was about long. From the width of its thighbone, its weight has been estimated at , dependent on its having been bipedal or quadrupedal respectively. Kamuysaurus Scale

The describing authors indicated some distinguishing traits. Three of these were

autapomorphies In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to ...

, unique derived characters. On the

quadrate bone The quadrate bone is a skull bone in most tetrapods, including amphibians, sauropsids ( reptiles, birds), and early synapsids. In most tetrapods, the quadrate bone connects to the quadratojugal and squamosal bones in the skull, and forms up ...

, the notch at the opening separating it from the

quadratojugal bone The quadratojugal is a skull bone present in many vertebrates, including some living reptiles and amphibians. Anatomy and function In animals with a quadratojugal bone, it is typically found connected to the jugal (cheek) bone from the front and ...

, is located at a very low position, at three quarters of the shaft length measured from the top of the element. This is unique for the

Hadrosauridae Hadrosaurids (), also hadrosaurs or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod fam ...

as a whole. The surangular bone of the lower jaw has only a short ascending branch, not reaching the coronoid process. The sixth tot thirteenth back vertebrae have

neural spine 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 ...

s that are inclined to the front.

References

{{Taxonbar, from=Q67170421 Saurolophinae Dinosaur genera Maastrichtian dinosaurs Fossil taxa described in 2019 Dinosaurs of Japan