Yinlong
Encyclopedia
Yinlong is a genus
of basal
ceratopsia
n dinosaur
from the Late Jurassic Period of central Asia
. It was a small, primarily biped
al herbivore
, approximately 1.2 meters (4 ft) long. Yinlong is the oldest and most primitive ceratopsian known to science.
A coalition of American
and Chinese
paleontologists, including Xu Xing, Catherine Forster, Jim Clark, and Mo Jinyou, described and named Yinlong in 2006. The generic name is derived from the Mandarin Chinese words 隱 (yǐn: "hidden") and 龍 (lóng: "dragon"), a reference to the movie Crouching Tiger, Hidden Dragon
, large portions of which were filmed in the western Chinese province of Xinjiang
, near the locality where this animal's fossil
remains were discovered. Long is the word most often used in the Chinese media when referring to dinosaurs.
Yinlong Species
The species
was named after the late Will Downs, a frequent participant in paleontological expeditions to China, who died the year before Yinlong was discovered.
The known fossil material of Yinlong consists of a single exceptionally well-preserved skeleton, complete with skull
, of a nearly adult animal, found in 2004 in the Middle
-Late Jurassic
strata of the Shishugou Formation
located in Xinjiang Province, China. Yinlong was discovered in an upper section of this formation which dates to the Oxfordian stage
of the Late Jurassic, or 161.2 to 155.7 million years ago. All other described ceratopsians are known from the later Cretaceous Period.
on the end of the upper jaw clearly identifies Yinlong as a ceratopsian, although the skull displays several features, especially the ornamentation of the squamosal
bone of the skull roof, which were previously thought to be unique to pachycephalosauria
ns. The presence of these features in Yinlong indicates these as actual synapomorphies
(unique features) of the larger group Marginocephalia, which contains both the pachycephalosaurs and the ceratopsians, although these features have been lost in all known ceratopsians more derived
than Yinlong. The addition of these characters further strengthens the support for Marginocephalia. Yinlong also preserves skull features reminiscent of the family Heterodontosauridae
, providing support for the hypothesis
that heterodontosaurids are closely related to marginocephalians (Cooper, 1985; Zhao et al., 1999; You et al., 2003). The group containing Marginocephalia and Heterodontosauridae has been named Heterodontosauriformes
(Xu et al., 2006).
s preserved in the abdominal cavity. Gastroliths, stones stored in the digestive tract and used to grind plant material, are also found in other ceratopsians such as Psittacosaurus
, and are also widely distributed in most other dinosaur groups, as well as in many types of bird
s.
. The documentary called Yinlong "a little ancestor of the giant dinosaurs like Triceratops
", while contrasting the shape of Yinlongs head to those of the later ceratopsian. The documentary highlighted the importance of the find, and stated that the fossil remains "give a snap-shot of dinosaur evolution".
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
ceratopsia
Ceratopsia
Ceratopsia or Ceratopia is a group of herbivorous, beaked dinosaurs which thrived in what are now North America, Europe, and Asia, during the Cretaceous Period, although ancestral forms lived earlier, in the Jurassic. The earliest known ceratopsian, Yinlong downsi, lived between 161.2 and 155.7...
n dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
from the Late Jurassic Period of central Asia
Central Asia
Central Asia is a core region of the Asian continent from the Caspian Sea in the west, China in the east, Afghanistan in the south, and Russia in the north...
. It was a small, primarily biped
Biped
Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs, or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning "two feet"...
al herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
, approximately 1.2 meters (4 ft) long. Yinlong is the oldest and most primitive ceratopsian known to science.
Discovery and Species
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
and Chinese
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
paleontologists, including Xu Xing, Catherine Forster, Jim Clark, and Mo Jinyou, described and named Yinlong in 2006. The generic name is derived from the Mandarin Chinese words 隱 (yǐn: "hidden") and 龍 (lóng: "dragon"), a reference to the movie Crouching Tiger, Hidden Dragon
Crouching Tiger, Hidden Dragon
Crouching Tiger, Hidden Dragon is a 2000 wuxia film. An American-Chinese-Hong Kong-Taiwanese co-production, the film was directed by Ang Lee and featured an international cast of ethnic Chinese actors, including Chow Yun-Fat, Michelle Yeoh, Zhang Ziyi, and Chang Chen...
, large portions of which were filmed in the western Chinese province of Xinjiang
Xinjiang
Xinjiang is an autonomous region of the People's Republic of China. It is the largest Chinese administrative division and spans over 1.6 million km2...
, near the locality where this animal's fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
remains were discovered. Long is the word most often used in the Chinese media when referring to dinosaurs.
Yinlong Species
- Y. downsi (type)
The species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
was named after the late Will Downs, a frequent participant in paleontological expeditions to China, who died the year before Yinlong was discovered.
The known fossil material of Yinlong consists of a single exceptionally well-preserved skeleton, complete with skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
, of a nearly adult animal, found in 2004 in the Middle
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from 176-161 million years ago. In European lithostratigraphy, rocks of this Middle Jurassic age are called the Dogger....
-Late Jurassic
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 161.2 ± 4.0 to 145.5 ± 4.0 million years ago , which is preserved in Upper Jurassic strata. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age...
strata of the Shishugou Formation
Shishugou Formation
The Shishugou Formation is a geological formation in Xinjiang, China, whose strata date back to the Late Jurassic period. Dinosaur remains are among the fossils that have been recovered from the formation....
located in Xinjiang Province, China. Yinlong was discovered in an upper section of this formation which dates to the Oxfordian stage
Oxfordian stage
The Oxfordian is, in the ICS' geologic timescale, the earliest age of the Late Jurassic epoch, or the lowest stage of the Upper Jurassic series. It spans the time between 161.2 ± 4 Ma and 155.7 ± 4 Ma...
of the Late Jurassic, or 161.2 to 155.7 million years ago. All other described ceratopsians are known from the later Cretaceous Period.
Classification
A small rostral boneRostral bone
The rostral bone is the edentulous dorsal component of the skeleton of the beak, unique to the ceratopsian dinosaurs. Othniel Charles Marsh recognized and named this bone, which acts as a mirror image of the predentary bone on the lower jaw....
on the end of the upper jaw clearly identifies Yinlong as a ceratopsian, although the skull displays several features, especially the ornamentation of the squamosal
Squamosal
The squamosal is a bone of the head of higher vertebrates. It is the principal component of the cheek region in the skull, lying below the temporal series and otic notch and bounded anteriorly by postorbital. Posteriorly, the squamosal articulates with the posterior elements of the palatal complex,...
bone of the skull roof, which were previously thought to be unique to pachycephalosauria
Pachycephalosauria
Pachycephalosauria is a clade of ornithischian dinosaurs. Well-known genera include Pachycephalosaurus, Stegoceras, Stygimoloch, and Dracorex. Most lived during the Late Cretaceous Period, in what is now North America and Asia. They were all bipedal, herbivorous/omnivorous animals with thick skulls...
ns. The presence of these features in Yinlong indicates these as actual synapomorphies
Synapomorphy
In cladistics, a synapomorphy or synapomorphic character is a trait that is shared by two or more taxa and their most recent common ancestor, whose ancestor in turn does not possess the trait. A synapomorphy is thus an apomorphy visible in multiple taxa, where the trait in question originates in...
(unique features) of the larger group Marginocephalia, which contains both the pachycephalosaurs and the ceratopsians, although these features have been lost in all known ceratopsians more derived
Derived
In phylogenetics, a derived trait is a trait that is present in an organism, but was absent in the last common ancestor of the group being considered. This may also refer to structures that are not present in an organism, but were present in its ancestors, i.e. traits that have undergone secondary...
than Yinlong. The addition of these characters further strengthens the support for Marginocephalia. Yinlong also preserves skull features reminiscent of the family Heterodontosauridae
Heterodontosauridae
Heterodontosauridae is a family of early ornithischian dinosaurs that were likely among the most basal members of the group...
, providing support for the hypothesis
Hypothesis
A hypothesis is a proposed explanation for a phenomenon. The term derives from the Greek, ὑποτιθέναι – hypotithenai meaning "to put under" or "to suppose". For a hypothesis to be put forward as a scientific hypothesis, the scientific method requires that one can test it...
that heterodontosaurids are closely related to marginocephalians (Cooper, 1985; Zhao et al., 1999; You et al., 2003). The group containing Marginocephalia and Heterodontosauridae has been named Heterodontosauriformes
Heterodontosauriformes
Heterodontosauriformes are a group of herbivorous dinosaurs within the order Ornithischia. The taxon was named by Xu et al. in 2006 to group the suborder Marginocephalia with the family Heterodontosauridae , after the discovery of Yinlong revealed the two to be closely related....
(Xu et al., 2006).
Diet
Yinlong was discovered with seven gastrolithGastrolith
A gastrolith, also called a stomach stone or gizzard stones, is a rock held inside a gastrointestinal tract. Gastroliths are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. The grain size depends upon the size of the animal and the gastrolith's...
s preserved in the abdominal cavity. Gastroliths, stones stored in the digestive tract and used to grind plant material, are also found in other ceratopsians such as Psittacosaurus
Psittacosaurus
Psittacosaurus is a genus of psittacosaurid ceratopsian dinosaur from the Early Cretaceous Period of what is now Asia, about 130 to 100 million years ago. It is notable for being the most species-rich dinosaur genus...
, and are also widely distributed in most other dinosaur groups, as well as in many types of bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s.
In popular culture
Yinlong made its first appearance in popular culture on the National Geographic Channel documentary "Dino Death Trap" as a prey item of GuanlongGuanlong
Guanlong was a genus of proceratosaurid tyrannosauroid dinosaur, one of the earliest known examples of the lineage.-Description and discovery:...
. The documentary called Yinlong "a little ancestor of the giant dinosaurs like Triceratops
Triceratops
Triceratops is a genus of herbivorous ceratopsid dinosaur which lived during the late Maastrichtian stage of the Late Cretaceous Period, around 68 to 65 million years ago in what is now North America. It was one of the last dinosaur genera to appear before the great Cretaceous–Paleogene...
", while contrasting the shape of Yinlongs head to those of the later ceratopsian. The documentary highlighted the importance of the find, and stated that the fossil remains "give a snap-shot of dinosaur evolution".
External links
- GW News Center, featuring a link to the original paper, pictures, and a press release on the discovery of Yinlong (site operated by George Washington UniversityGeorge Washington UniversityThe George Washington University is a private, coeducational comprehensive university located in Washington, D.C. in the United States...
)