''Yunganglong'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

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 basal

hadrosauroid Hadrosauroidea is a clade or superfamily of ornithischian dinosaurs that includes the "duck-billed" dinosaurs, or Hadrosauridae, and all dinosaurs more closely related to them than to ''Iguanodon''. Their remains have been recovered in Asia, Euro ...

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 ...

known from the early

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 ...

lower

Zhumapu Formation The Zhumapu Formation is an early Late Cretaceous (estimated Cenomanian)Wang et al., 2015, p.3 geologic formation in Shanxi Province, China. The hadrosauroids '' Yunganglong'' and ''Zuoyunlong''Wang et al., 2013, p.4Wang et al., 2015, p.2 and the ...

Zuoyun County Zuoyun County is a county in the north of Shanxi province, China, bordering Inner Mongolia to the north. It is the westernmost county-level division of the prefecture-level city of Datong Datong is a prefecture-level city in northern Shanxi ...

Shanxi Province Shanxi; formerly romanised as Shansi is a province in North China. Its capital and largest city of the province is Taiyuan, while its next most populated prefecture-level cities are Changzhi and Datong. Its one-character abbreviation is ( ...

of northeastern

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

. It contains a single species, ''Yunganglong datongensis''.

Discovery and naming

''Yunganglong'' was first described and named by Run-Fu Wang, Hai-Lu You, Shi-Chao Xu, Suo-Zhu Wang, Jian Yi, Li-Juan Xie, Lei Jia and Ya-Xian Li in

2013 2013 was the first year since 1987 to contain four unique digits (a span of 26 years). 2013 was designated as: *International Year of Water Cooperation *International Year of Quinoa Events January * January 5 – 2013 Craig, Alask ...

and 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 ...

is ''Y. datongensis''. The generic name honors

Yungang Grottoes The Yungang Grottoes (), formerly the Wuzhoushan Grottoes (), are ancient Chinese Buddhist temple grottoes built during the Northern Wei dynasty near the city of Datong, then called Pingcheng, in the province of Shanxi. They are excellent exampl ...

, a

UNESCO World Heritage site World Heritage Sites are landmarks and areas with legal protection under an treaty, international treaty administered by UNESCO for having cultural, historical, or scientific significance. The sites are judged to contain "cultural and natural ...

built in the 5th and 6th centuries about 50 km east of the fossil locality, and derived from ''long'' meaning "

dragon A dragon is a Magic (supernatural), magical legendary creature that appears in the folklore of multiple cultures worldwide. Beliefs about dragons vary considerably through regions, but European dragon, dragons in Western cultures since the Hi ...

" in

Chinese Chinese may refer to: * Something related to China * Chinese people, people identified with China, through nationality, citizenship, and/or ethnicity **Han Chinese, East Asian ethnic group native to China. **'' Zhonghua minzu'', the supra-ethnic ...

. 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 ...

refers to the city of

Datong Datong is a prefecture-level city in northern Shanxi Province, China. It is located in the Datong Basin at an elevation of and borders Inner Mongolia to the north and west and Hebei to the east. As of the 2020 census, it had a population o ...

, located in northern

Shanxi province Shanxi; formerly romanised as Shansi is a province in North China. Its capital and largest city of the province is Taiyuan, while its next most populated prefecture-level cities are Changzhi and Datong. Its one-character abbreviation is ( ...

, where the holotype was found. Cervical vertebra of Yunganglong

''Yunganglong'' is known solely from 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 ...

SXMG V 00001, field number ZY007, an associated but disarticulated partial

skeleton A skeleton is the structural frame that supports the body of most animals. There are several types of skeletons, including the exoskeleton, which is a rigid outer shell that holds up an organism's shape; the endoskeleton, a rigid internal fra ...

housed at the Shanxi Museum of Geology. The holotype came from a single individual, and includes the caudodorsal part of the skull, ZY007-37 and ZY007-38, separated along the floor of the

braincase In human anatomy, the neurocranium, also known as the braincase, brainpan, brain-pan, or brainbox, is the upper and back part of the skull, which forms a protective case around the brain. In the human skull, the neurocranium includes the calv ...

; two

cervical vertebrae 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 saurop ...

ZY007-40 and ZY007-41; partial dorsal neural arch and neural processes ZY007-36; two

caudal vertebrae Caudal vertebrae are the vertebrae of the tail in many vertebrates. In birds, the last few caudal vertebrae fuse into the pygostyle, and in apes, including humans, the caudal vertebrae are fused into the coccyx. In many reptiles, some of the caud ...

, including the proximal ZY007-27 and the middle ZY007-19; distal portions of 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 ...

(left ZY007-11 and right ZY007-12, distal end of left

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 ...

ZY007-32, proximal portion of right

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 ...

ZY007-1, and distal portion of left tibia with astragalus ZY007-2. The remains were collected in 2011 from Locality 7 of the

, as a part of a project to find dinosaurs for the Shanxi Museum of Geology, initiated by the Department of Land and Resources of Shanxi Province. SXMG V 00001 was found in the vicinity of

, from the lower part of Zhumapu Formation, dating to the early

based on

biostratigraphic Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.Hine, Robert. "Biostratigraphy." ''Oxford Reference: Dictionary of Biology ...

correlations, overlying the late

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 ...

Zuoyun Formation. Other than SXMG V 00001,

ankylosaur Ankylosauria is a group of herbivorous dinosaurs of the clade Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms, similar to turtles. Ankylosaurs were bulky quadrupeds, with short, powerful l ...

and

ceratopsia Ceratopsia or Ceratopia ( or ; Ancient Greek, Greek: "horned faces") is a group of herbivore, herbivorous, beaked dinosaurs that thrived in what are now North America, Asia and Europe, during the Cretaceous Period (geology), Period, although ance ...

n remains were found from the newly discovered localities. The first dinosaur record in Shanxi Province was reported by Young (1958), from two localities in Zuoyun County. He assigned hadrosauroid material recovered from the Xinyaogou locality of the Zuoyun area to ''

Bactrosaurus johnsoni ''Bactrosaurus'' (; meaning "Club lizard," "baktron" = club + ''sauros'' = lizard) is a genus of herbivorous hadrosauroid dinosaur that lived in Asia during the Late Cretaceous, from about 96 to 85 million years ago. The position ''Bactrosaurus'' ...

'', including two isolated teeth, some vertebrae including a series of 25 caudal vertebrae, one

rib In vertebrate anatomy, ribs () are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the thoracic cavity, enabling the lungs to expand and thus facilitate breathing by expanding the ...

, one right

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 ...

and several manual and pedal bones. Although no overlapping material exists, based on the more basal phylogenetic position and lower stratigraphic horizon of ''Yunganglong'' compared to ''Bactrosaurus'', Young's material more probably pertains to ''Yunganglong''.

Description

Wang ''et al.'' (2013) diagnosed ''Yunganglong datongensis'' using a unique combination of four characters. The caudal surface of the supraoccipital in ''Yunganglong'' and more advanced hadrosauroids is inclined steeply forward at approximately 45°, while nearly vertical in '' Jintasaurus'' and less derived Hadrosauriformes. The horizontal portion of the paroccipital process is caudolaterally extended and accompanied by the

squamosal The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. The bone forms an ancestra ...

, but laterally extended in ''Jintasaurus'' and less derived Hadrosauriformes. As observed in ''Yunganglong'' and ''Jintasaurus'', but not in ''Bactrosaurus'' and more advanced taxa, the pendent portion of the paroccipital process does not curve cranially. Finally, ''Yunganglong'' and less derived Hadrosauriformes possess a deep, U-shaped, intercondylar extensor groove on the

, partially enclosed by expansion of medial and lateral

condyles A condyle (;Entry "condyle"
in

, while in more advanced taxa (e.g. ''

Nanyangosaurus ''Nanyangosaurus'' is a genus of herbivorous ornithischian dinosaur belonging to Hadrosauroidea that lived in the Late Cretaceous of present-day Henan Province, China. In 1994, the remains of ''Nanyangosaurus'' were found near the village of Ho ...

'') it is fully enclosed. ''Yunganglong'' cannot be directly compared with three other non-hadrosaurid hadrosauroids. These include '' Shuangmiaosaurus'' from the early Late Cretaceous of

Liaoning Province ) , image_skyline = , image_alt = , image_caption = Clockwise: Mukden Palace in Shenyang, Xinghai Square in Dalian, Dalian coast, Yalu River at Dandong , image_map = Liaoning in China (+all claims hatched).svg , ...

of northeastern China, and two other early Late Cretaceous taxa from North America: the

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

Protohadros ''Protohadros'' (meaning "first hadrosaur") is a genus of herbivorous ornithischian dinosaur from the Late Cretaceous (Cenomanian stage). Gary Byrd, a part-time palaeontologist, discovered some remains of this euornithopod (ribs and an ungual) ...

'' and the

Turonian The Turonian is, in the International Commission on Stratigraphy, ICS' geologic timescale, the second age (geology), age in the Late Cretaceous epoch (geology), Epoch, or a stage (stratigraphy), stage in the Upper Cretaceous series (stratigraphy), ...

Jeyawati ''Jeyawati'' (meaning "grinding mouth" in the Zuni language) is a genus of hadrosauroid dinosaur which lived during the Turonian stage of the Late Cretaceous. The type species, ''J. rugoculus'', was described in 2010, based on fossils recovered i ...

''. Like other hadrosauroids, ''Yunganglong'' was a ground-dwelling

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

that could walk

bipedal Bipedalism is a form of terrestrial locomotion where an animal moves by means of its two rear (or lower) limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning 'two feet' (from Latin ''bis'' ...

ly, and could stand on all four legs. The skull of ''Yunganglong'' is relatively wide and low.

Phylogeny

Based on its

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

Wang et al. (2013) showed that ''Yunganglong'' was more derived than the basal hadrosauriform ''

Iguanodon ''Iguanodon'' ( ; meaning 'iguana-tooth'), named in 1825, is a genus of iguanodontian dinosaur. While many species found worldwide have been classified in the genus ''Iguanodon'', dating from the Late Jurassic to Early Cretaceous, Taxonomy (bi ...

'' but more primitive than the

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 ...

s, such as the well known ''

Edmontosaurus ''Edmontosaurus'' ( ) (meaning "lizard from Edmonton"), with the second species often colloquially and historically known as ''Anatosaurus'' or ''Anatotitan'' (meaning "duck lizard" and "giant duck"), is a genus of hadrosaurid (duck-billed) din ...

'' and ''

Corythosaurus ''Corythosaurus'' (; ) is a genus of hadrosaurid "duck-billed" dinosaur from the Late Cretaceous Period (geology), period, about 77–75.7 million years ago, in what is now Laramidia, western North America. Its name is derived from the Anci ...

''. To further explore the

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

position of ''Y. datongensis'' among

hadrosauriform Ankylopollexia is an extinct clade of ornithischian dinosaurs that lived from the Late Jurassic to the Late Cretaceous. It is a derived clade of iguanodontian ornithopods and contains the subgroup Styracosterna. The name stems from the Greek word ...

s, Wang ''et al.'' (2013) used a modified version of the data matrix first presented by Sues and Averianov (2009). ''

'', '' Shuangmiaosaurus'', and ''Yunganglong'' were added to the matrix, and two character codings were modified. In the strict consensus tree, ''Yunganglong'' was recovered as more advanced than ''

Probactrosaurus ''Probactrosaurus'' (meaning "before ''Bactrosaurus''") is an early herbivorous hadrosauroid iguanodont dinosaur. It lived in China during the Early Cretaceous Period (geology), period. Discovery and species In 1959 and 1960 a Soviet-Chinese ex ...

'', in an unresolved

polytomy An internal node of a phylogenetic tree is described as a polytomy or multifurcation if (i) it is in a rooted tree and is linked to three or more child subtrees or (ii) it is in an unrooted tree and is attached to four or more branches. A tree ...

with '' Jintasaurus'', ''

'', ''Nanyangosaurus'', ''Shuangmiaosaurus'', '' Levnesovia'', ''

Bactrosaurus ''Bactrosaurus'' (; meaning "Club lizard," "baktron" = club + ''sauros'' = lizard) is a genus of herbivorous hadrosauroid dinosaur that lived in Asia during the Late Cretaceous, from about 96 to 85 million years ago. The position ''Bactrosaurus'' ...

'', ''

Tanius ''Tanius'' (meaning "of Tan") is a genus of hadrosauroid dinosaur. It lived in the Late Cretaceous of China. The type species, named and described in 1929 by Carl Wiman, is ''Tanius sinensis''. The generic name honours the Chinese paleontologist ...

'', ''

Telmatosaurus ''Telmatosaurus'' (meaning "marsh lizard") is a genus of basal (phylogeny), basal hadrosauromorph dinosaur from the Late Cretaceous of Romania. It was a relatively small hadrosaur, measuring approximately in length and in body mass, which has b ...

'' and the clade formed by ''Aralosaurus'' and

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 ...

. The 50% majority rule tree resolved its phylogenetic position further, as shown in the

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 ...

below.

References

{{Taxonbar, from=Q15079382 Hadrosauroidea Dinosaur genera Cenomanian dinosaurs Dinosaurs of China Fossil taxa described in 2013 Taxa named by Hailu You