Yandusaurus
Encyclopedia
Yandusaurus is a genus
of herbivorous basal euornithopod dinosaur
from the Bathonian
age (middle Jurassic
, approximately 169 to 163 Ma) of China
.
in Sichuan
was warned that during construction activities with a composter at Jinzidang near the Honghe dam inadvertently a dinosaur skeleton had been processed. A team of the museum managed to salvage some heavily damaged remains. Though locally this animal was at first referred to as "Yubasaurus" or "Honghesaurus", in 1979 Beijing
professor He Xinlu named and described it as the type species
Yandusaurus hongheensis. The generic name is derived from Yandu, the ancient name for Zigong. This name is a contraction of yan, "salt", and du, "capital", occasioned by the fact that Zigong was historically the centre of Chinese salt mining. In this way Yandusaurus indirectly also refers to the Salt Museum. The specific name refers to the Honghe river.
The holotype
specimen, GCC V20501, had been dug up in a layer of the Lower Shaximiao Formation. It consists of a partial skeleton with skull. Elements of most parts of the body have been preserved, the skull, vertebral column, shoulder girdle, frontlimbs and hindlimbs but all are very limited and/or damaged. The lower jaws, pelvis and the end of the tail had probably been entirely destroyed by the machine.
In 1983 He and Cai Kaiji identified a second species: Yandusaurus multidens, known from two nearly complete skeletons and nine partial skeletons. In 1992 this was by Guangzhao Peng re-assigned to the genus Agilisaurus
as a A. multidens. In 1996 Gregory S. Paul
renamed it as Othnielia
multidens. In 2005 it was by Paul Barrett
e.a. placed in its own genus, Hexinlusaurus
.
. The teeth, showing a unique pattern of parallel vertical ridges compared by Chinese researchers to the fingers of the hand of Buddha statues, are very asymmetrical in that the inner side is strongly worn down. The fifteen maxillary
teeth are largest in the middle and overlap.
When indicating the size of Yandusaurus many sources give that of Hexinlusaurus, the previous Y. multidens, the (all juvenile) specimens of which are sixty centimetres (two feet) to 1.6 metres (5 ft) in length, and weighed around seven kilogram
s (fifteen lb
). Yandusaurus hongheensis was however considerably larger than these exemplars: He estimated the body length at three metres, Peng at 3.2 metres; in 2010 G.S. Paul gave an estimation of 3.8 metres length and a weight of hundred forty kilogrammes.
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 herbivorous basal euornithopod 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 Bathonian
Bathonian
In the geologic timescale the Bathonian is an age or stage of the Middle Jurassic. It lasted from approximately 167.7 Ma to around 164.7 Ma...
age (middle Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
, approximately 169 to 163 Ma) of China
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...
.
Discovery and naming
In January 1973 the Museum of the Salt Industry at ZigongZigong
Zigong , ancient name Ziliujing and Gongjing, is a prefecture-level city and the third largest city in Sichuan Province, in southwest China.-Geography:...
in Sichuan
Sichuan
' , known formerly in the West by its postal map spellings of Szechwan or Szechuan is a province in Southwest China with its capital in Chengdu...
was warned that during construction activities with a composter at Jinzidang near the Honghe dam inadvertently a dinosaur skeleton had been processed. A team of the museum managed to salvage some heavily damaged remains. Though locally this animal was at first referred to as "Yubasaurus" or "Honghesaurus", in 1979 Beijing
Beijing
Beijing , also known as Peking , is the capital of the People's Republic of China and one of the most populous cities in the world, with a population of 19,612,368 as of 2010. The city is the country's political, cultural, and educational center, and home to the headquarters for most of China's...
professor He Xinlu named and described it as the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
Yandusaurus hongheensis. The generic name is derived from Yandu, the ancient name for Zigong. This name is a contraction of yan, "salt", and du, "capital", occasioned by the fact that Zigong was historically the centre of Chinese salt mining. In this way Yandusaurus indirectly also refers to the Salt Museum. The specific name refers to the Honghe river.
The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
specimen, GCC V20501, had been dug up in a layer of the Lower Shaximiao Formation. It consists of a partial skeleton with skull. Elements of most parts of the body have been preserved, the skull, vertebral column, shoulder girdle, frontlimbs and hindlimbs but all are very limited and/or damaged. The lower jaws, pelvis and the end of the tail had probably been entirely destroyed by the machine.
In 1983 He and Cai Kaiji identified a second species: Yandusaurus multidens, known from two nearly complete skeletons and nine partial skeletons. In 1992 this was by Guangzhao Peng re-assigned to the genus Agilisaurus
Agilisaurus
Agilisaurus is a genus of ornithischian dinosaur from the Middle Jurassic Period of what is now eastern Asia. The name is derived from the Latin agilis meaning 'agile' and the Greek sauros meaning 'lizard', and refers to the agility suggested by its lightweight skeleton and long legs...
as a A. multidens. In 1996 Gregory S. Paul
Gregory S. Paul
Gregory Scott Paul is a freelance researcher, author and illustrator who works in paleontology, and more recently has examined sociology and theology. He is best known for his work and research on theropod dinosaurs and his detailed illustrations, both live and skeletal...
renamed it as Othnielia
Othnielia
Othnielia is a genus of ornithischian dinosaur, named after its original describer, Professor Othniel Charles Marsh, an American paleontologist of the 19th century...
multidens. In 2005 it was by Paul Barrett
Paul Barrett
Paul Franklyn "Legs" Barrett is the UK's best known agent and manager of 1950s style Rock and Roll artistes, an author and previously a singer and film actor...
e.a. placed in its own genus, Hexinlusaurus
Hexinlusaurus
Hexinlusaurus is a genus of basal ornithischian dinosaur from the Middle Jurassic of China. The holotype , consists of an almost complete, articulated skull and some postcranial material, collected from a terrestrial sandstone within the Lower Shaximiao Formation at the famous dinosaur-bearing...
.
Description
A fast-moving biped, Yandusaurus had four toes on each foot and five fingers on each hand. It had large eyes as shown by the curved jugalJugal
The jugal is a skull bone found in most reptiles, amphibians, and birds. In mammals, the jugal is often called the malar or Zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by species....
. The teeth, showing a unique pattern of parallel vertical ridges compared by Chinese researchers to the fingers of the hand of Buddha statues, are very asymmetrical in that the inner side is strongly worn down. The fifteen maxillary
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
teeth are largest in the middle and overlap.
When indicating the size of Yandusaurus many sources give that of Hexinlusaurus, the previous Y. multidens, the (all juvenile) specimens of which are sixty centimetres (two feet) to 1.6 metres (5 ft) in length, and weighed around seven kilogram
Kilogram
The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water...
s (fifteen lb
Pound (mass)
The pound or pound-mass is a unit of mass used in the Imperial, United States customary and other systems of measurement...
). Yandusaurus hongheensis was however considerably larger than these exemplars: He estimated the body length at three metres, Peng at 3.2 metres; in 2010 G.S. Paul gave an estimation of 3.8 metres length and a weight of hundred forty kilogrammes.