''Jinyunpelta'' ("Jinyun shield") is a genus of herbivorous ankylosaurine thyreophoran

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 ...

from the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

Liangtoutang Formation of

Jinyun County Jinyun County () is a county of south-central Zhejiang province, China. It is under the administration of the Lishui City. Administrative divisions Towns: * Wuyun (五云镇), Huzhen (壶镇镇), Xinjian (新建镇), Shuhong (舒洪镇), Day ...

Zhejiang Zhejiang ( or , ; , Chinese postal romanization, also romanized as Chekiang) is an East China, eastern, coastal Provinces of China, province of the People's Republic of China. Its capital and largest city is Hangzhou, and other notable citie ...

, China; it has one species, the

type species In 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 species that contains the biological type specime ...

''J. sinensis''. This species is the basalmost ankylosaur known to have had a proper tail club.

Discovery and naming

In June 2008, farmer Li Meiyun on a construction site at Huzhen in

discovered the remains of an ankylosaur. Between 2008 and 2014 excavations took place by a joint team of the Zhejiang Museum of Natural History, the Jinyun Museum and the Fukui Prefectural Dinosaur Museum. In 2013, five ankylosaurian skeletons were uncovered. A new species was to be based on two of these, while preparation of the other finds continued. In 2018, the type species ''Jinyunpelta sinensis'' was named and described by Zheng Wenjie, Jin Xingsheng, Yoichi Azuma, Wang Qiongying, Kazunori Miyata and Xu Xing. The generic name combines Jinyun with a Greek ''peltè'', "small shield", a usual suffix in the names of ankylosaurians. The specific name refers to the provenance from China. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

, ZMNH M8960, was found in a layer of the Liangtoutang Formation dating from the

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/ Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± 0 ...

- Cenomanian, about one hundred million years old. It consists of a partial skeleton, with a complete skull, but lacking most of the hindlimbs, apart from the right humerus and the left thighbone. The

paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype nor a syntype). O ...

is ZMNH M8963, a skeleton lacking the skull but including the left lower leg and a complete tail club. It was found at two to three metres distance from the holotype.

Description

The describing authors indicated a number of distinguishing traits. Some 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 t ...

, unique derived characters. Behind the nostril two additional openings are present, in ankylosaurids named the "C1" and the "C2", which in the case of ''Jinyunpelta'' are on a level with the centre of the nostril. On the front upper edge of the

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...

a triangular depression is present. The postorbital bone does not contribute to the rear edge of the eye socket. In the lower jaw, the front part of the prearticular bone is positioned beneath the rear part of the splenial bone. Obliquely above and to the inside of the inner condyle of the thighbone a distinct tendon scar is present. Additionally, ''Jinyunpelta'' shows a unique combination of traits that in themselves are not unique. The combined upper side of the nasal bones is pierced by two paired oval openings. The antorbital fossa, with ankylosaurs the remnant of the

antorbital fenestra An antorbital fenestra (plural: fenestrae) is an opening in the skull that is in front of the eye sockets. This skull character is largely associated with archosauriforms, first appearing during the Triassic Period. Among extant archosaurs, bird ...

, extends over the contact point of the maxilla, lacrimal bone and jugal bone. The prefrontal bone extends to below, touching the maxilla. At least some dorsal vertebrae have an elongated centrum, 30% longer than wide. The tail club is hexagonal in top view, with the widest point located near the rear edge.

Phylogeny

In 2018, ''Jinyunpelta'' was, within the

Ankylosauridae Ankylosauridae () is a family of armored dinosaurs within Ankylosauria, and is the sister group to Nodosauridae. The oldest known Ankylosaurids date to around 122 million years ago and went extinct 66 million years ago during the Cretaceous–Pa ...

, placed in the

Ankylosaurinae Ankylosaurinae is a subfamily of ankylosaurid dinosaurs, existing from the Early Cretaceous about 105 million years ago until the end of the Late Cretaceous, about 66 mya. Many genera are included in the clade, such as ''Ankylosaurus'', ''Pina ...

. This would imply that it was the oldest known ankylosaurine. A

cladistic Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived char ...

analysis showed that it was also the basalmost known ankylosaurine, placed below '' Crichtonpelta'' in the evolutionary tree. It would then furthermore be the oldest and basalmost ankylosaurid that is with certainty known to possess a tail club; previously this had been ''

Pinacosaurus ''Pinacosaurus'' (meaning "Plank lizard") is a genus of ankylosaurid thyreophoran dinosaur that lived in Asia during the Late Cretaceous (Santonian-Campanian, roughly 75 million to 71 million years ago), mainly in Mongolia and China. The first r ...

'' dating from the

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campani ...

. The size of the tail club shows that this trait must have been developed early-on in the evolution of ankylosaurids. Additionally, ''Jinyunpelta'' was the most southern known ankylosaurid from Asia.

References

{{Taxonbar, from=Q50244145 Ankylosaurids Late Cretaceous dinosaurs of Asia Fossil taxa described in 2018 Ornithischian genera

Discovery and naming

Description

Phylogeny

See also

References