Tsintaosaurus

Tsintaosaurus (/tʃɪŋdaʊˈsɔːrəs/; meaning "Qingdao lizard", after the old transliteration "Tsingtao") [2] is a genus of hadrosaurid dinosaur from China. It was about 8.3 metres (27 ft) long and weighed 2.5 tonnes.[3] The type species is Tsintaosaurus spinorhinus, first described by Chinese paleontologist C. C. Young in 1958.

A hadrosaur, Tsintaosaurus had a characteristic 'duck bill' snout and a battery of powerful teeth which it used to chew vegetation. It usually walked on all fours, but could rear up on its hind legs to scout for predators and flee when it spotted one. Like other hadrosaurs, Tsintaosaurus probably lived in herds.

Tsintaosaurus
Temporal range: Late Cretaceous, 70 Ma
Tsintaosaurus nasal
Holotype skull with broken crest
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Ornithischia
Suborder: Ornithopoda
Family: Hadrosauridae
Tribe: Tsintaosaurini
Genus: Tsintaosaurus
Young, 1958[1]
Type species
Tsintaosaurus spinorhinus
Young, 1958[1]

Discovery and naming

Premaxilla of Tsintaosaurus
Left premaxilla

In 1950, at Hsikou, near Chingkangkou, in Laiyang, Shandong, in the eastern part of China, various remains of large hadrosaurids were uncovered. In 1958 these were described by Chinese paleontologist Yang Zhongjian ("C.C. Young") as the type species Tsintaosaurus spinorhinus. The generic name is derived from the city of Qingdao, earlier often transliterated as "Tsintao". The specific name means "with a nose spine", from Latin spina, and Greek ῥίς, rhis, "nose", in reference to the distinctive crest on the snout.[1]

The holotype, IVPP AS V725, was discovered in a layer of the Jingangkou Formation dating from the Campanian. It consists of a partial skeleton with skull. The paratype is specimen IVPP V818, a skull roof. In the same area some additional partial skeletons and a large number of disarticulated skeletal elements were found. Some of these were by Yang referred to Tsintaosaurus, others were named as a Tanius chingkankouensis Yang 1958; also a Tanius laiyangensis Zhen 1976 exists. The latter two species are today either considered junior synonyms or nomina dubia. Later researchers would refer a larger part of the material to Tsintaosaurus.

Description

Crest

Tsintaosaurus-spinorhinus-steveoc86
Restoration showing modern interpretation of crest shape

Tsintaosaurus was originally reconstructed with a unicorn-like crest on its skull. The crest, as preserved, consists of an about forty centimetres long process, protruding almost vertically from the top of the rear snout. The structure is hollow and seems to have a forked upper end. Comparable structures with related species are unknown: they possess more lobe-like crests. In 1990, David Weishampel and Jack Horner cast doubt on the presence of the crest, suggesting that it was actually a broken nasal bone from the top of the snout distorted upward by a crushing of the fossil. Their study further suggested that, without the distinctive crest to distinguish it, Tsintaosaurus was actually a synonym of the similar but crestless hadrosaur Tanius. However, in 1993 Eric Buffetaut e.a., after a renewed investigation of the bones themselves, concluded that the crest was neither distorted nor an artefact of restoration; besides, a second specimen with an upright crest part had since been discovered, indicating that the crest was indeed real and Tsintaosaurus is likely a distinct genus.[4]

TsintaosaurusSpinorhinus-PaleozoologicalMuseumOfChina-May23-08
Tsintaosaurus mount with outdated crest reconstruction, Paleozoological Museum of China.

A new reconstruction in 2013, by Albert Prieto-Márquez and Jonathan Wagner and based on the identification of specimen IVPP V829, a praemaxilla, as a Tsintaosaurus element, came to the conclusion that the unicorn-like bone was just the rear part of a larger cranial crest that started from the tip of the snout. The front of the crest would have been formed by ascending processes of the praemaxillae. These had expanded rhomboid contact facets with the expanded upper parts of the crest processes of the nasal bones, forming the rear of the crest. The rear base of the crest was covered by outgrowths of the prefrontals. The fused nasal bones would have formed a hollow tubular structure. The height of the crest would have exceeded that of the rear skull, measured along the quadrates. Though largely vertical, the crest is directed slightly to the rear; the forward inclination of the holotype crest would be the result of a distortion of the fossil.[5]

Tsintaosaurus spinorhinus
Reinterpretation of the skull crest

The new reconstruction by Prieto-Márquez and Wagner also led to a new hypothesis about the internal air passages of the crest. Yang had assumed that the tubular hollowing in the preserved part of the holotype would have served as the main intake of air. This was rejected by Prieto-Márquez and Wagner who pointed out that the tube was closed at its lower end and that with lambeosaurines in general the air passages are located in a more forward position, the bony nostrils being completely enclosed by the praemaxillae. They assumed that Tsintaosaurus would have had a standard lambeosaurine arrangement in the snout, the air, when inhaling, entering the skull through the paired pseudonares, the "fake nostrils" of the praemaxillae behind the upper beak. From there the air would have been transported through paired passages below the median processes of the praemaxillae to the top of the crest, subsequently entering a common median chamber within the lobe. The rear of the chamber was formed by the nasal bones and probably homologous to the nasal cavity. The chamber was divided into two smaller cavities, one at the front, the other at the rear, by curved median processes of the praemaxillae, forming hooks around a passage between the cavities. From the rear cavity the air was transported to below, towards the internal skull cavity. Although it is usually assumed that a single passage served for this purpose, Prieto-Márquez and Wagner saw indications in the form of the nasal that there were paired downward passages, to the inside of the lateral processes of the praemaxillae. From this they concluded that the entire airflow was likely separated, the common medium chamber probably being divided into a left and right section by a cartilaginous septum.[5]

The conclusion that the tubular structure in the rear nasal bones was not an air passage, forced Prieto-Márquez and Wagner to find an alternative explanation of its function. They suggested that it would have served to lessen the weight of the crest, such a tube combining relative strength with a low bone mass. Tsintaosaurus would have differed in this from more derived lambeosaurines, which have a front extension of the frontal bone, in the form of a bone sheet, supporting the crest.[5]

Other distinctive traits

Tsintaosaurus Scale
Size of Tsintaosaurus compared to a human

Apart from the crest, Prieto-Márquez and Wagner identified several other distinctive traits (autapomorphies) of Tsintaosaurus. The rim of the upper beak is rounded and thick, wider than the transverse width of the front depression around the nostrils. As far as this depression is situated on the praemaxillae, it is at each side divided lengthwise by two ridges obliquely continuing to below and sideways. Internally, the fused nasal bones form a bony block in front of the braincase. The rear of the nasal bone is clipped by front extensions of the frontal bone, the topmost of which is elevated relative to the skull roof. The ascending branches of the praemaxillae have internal processes pointing to behind, below and slightly inside, dividing a shared chamber at the midline. The prefrontal possesses a flange, continuing from the lower part of the lacrimal bone to the lower part of the ascending process of the prefrontal, and connecting to a process on the side of the praemaxilla to form an elevation on the side of the crest base. The side and the underside of the prefrontal show deep vertical grooves. The supratemporal fenestra is, transversely, wider than long.[5]

Classification

Tsintaosaurus may form a clade in Lambeosaurinae with the European genera Pararhabdodon and Koutalisaurus (probable synonym of Pararhabdodon).[6]

The position of Tsintaosaurus in the evolutionary tree according to a 2013 study by Prieto-Márquez e.a. is indicated by this cladogram:[7]

Prefrontal of Tsintaosaurus
Left prefrontal
 Lambeosaurinae 
Aralosaurini

Aralosaurus

Canardia

Jaxartosaurus

Tsintaosaurini

Tsintaosaurus

Pararhabdodon

Parasaurolophini

Charonosaurus

Parasaurolophus

Parasaurolophus cyrtocristatus

Parasaurolophus tubicen

Parasaurolophus walkeri

Lambeosaurini
Lambeosaurus

Lambeosaurus lambei

Lambeosaurus magnicristatus

Corythosaurus

Corythosaurus casuarius

Corythosaurus intermedius

"Hypacrosaurus" stebingeri

Hypacrosaurus

Olorotitan

Arenysaurus

Blasisaurus

Magnapaulia

Velafrons

Amurosaurus

Sahaliyania

Paleoecology

A study of dinosaur eggs in successive layers of the Wangshi Series of Shandong province, of which the Jingangkou Formation is the most recent layer, shows that the region was one of high dinosaur diversity and that the climate had become drier from the preceding Jiangjunding Formation.[8]

See also

References

  1. ^ a b c Young, C.-C. (1958). "The dinosaurian remains of Laiyang, Shantung". Palaeontologia Sinica, New Series C. Whole Number. 42 (16): 1–138.
  2. ^ Creisler, B. (2002). "Dinosauria Translation and Pronunciation Guide T". DOL Dinosaur Omnipedia. Archived from the original on 31 December 2005. Retrieved 24 Feb 2010.
  3. ^ Gregory S. Paul (2010). The Prince Field Guide to Dinosaurs. United States: Princeton University Press. p. 308. ISBN 978-0-691-13720-9.
  4. ^ Buffetaut, E.; Tong, H. (1993). "Tsintaosaurus spinorhinus Young and Tanius sinensis Wiman: a preliminary comparative study of two hadrosaurs (Dinosauria) from the Upper Cretaceous of China". 2. 317. C.R. Academy of Science Paris: 1255–1261.
  5. ^ a b c d Prieto-Márquez, A.; Wagner, J. R. (2013). "The 'Unicorn' Dinosaur That Wasn't: A New Reconstruction of the Crest of Tsintaosaurus and the Early Evolution of the Lambeosaurine Crest and Rostrum". PLOS ONE. 8 (11): e82268. doi:10.1371/journal.pone.0082268. PMC 3838384.
  6. ^ Prieto-Márquez, A.; Wagner, J. R. (2009). "Pararhabdodon isonensis and Tsintaosaurus spinorhinus: a new clade of lambeosaurine hadrosaurids from Eurasia". Cretaceous Research. online preprint: 1238–1246. doi:10.1016/j.cretres.2009.06.005.
  7. ^ Prieto-Marquez, A.; Vecchia, F. M. D.; Gaete, R.; Galobart, A. (2013). "Diversity, relationships, and biogeography of the Lambeosaurine dinosaurs from the European archipelago, with description of the new aralosaurin Canardia garonnensis". PLOS ONE. 8 (7): e69835. doi:10.1371/journal.pone.0069835. PMC 3724916. PMID 23922815.
  8. ^ Zhao, ZiKui; Zhang, ShuKang; Wang, Qiang; Wang, XiaoLin (2013). "Dinosaur diversity during the transition between the middle and late parts of the Late Cretaceous in eastern Shandong Province, China: Evidence from dinosaur eggshells". Chinese Science Bulletin. 58 (36): 4663–4669. doi:10.1007/s11434-013-6059-9.
"Tanius" laiyangensis

"Tanius" laiyangensis is a dubious species of kritosaurin hadrosaur from the Late Cretaceous Wangshi Group of Shandong, China. It was originally described in 1976 as the third species in the genus Tanius, based on a sacrum and partial ilium. The type species of the genus, Tanius sinensis, was later found to be a basal hadrosauroid as opposed to be a member of Hadrosauridae. T. laiyangensis was, after its description, variously considered a nomen dubium or a synonym of the lambeosaur Tsintaosaurus. In 2019, T. laiyangensis was re-evaluated, and found to be an indeterminate kritosaur, unrelated to the true Tanius. Material from the same formation, initially referred to the edmontosaur Laiyangosaurus, was also identified as being from a kritosaur, and so possibly belonged to the same species. It is the first recognized kritosaur to be found in Asia, and its closest relative was found to be Secernosaurus from Argentina.

Amurosaurus

Amurosaurus (; "Amur lizard") is a genus of lambeosaurine hadrosaurid dinosaur found in the latest Cretaceous period (66 million years ago) of eastern Asia. Like most lambeosaurs, it would have been a primarily bipedal herbivore with a "duckbill" shaped snout and a hollow crest on top of its head, although such a crest has not been found. Fossil bones of adults are rare, but an adult would most likely have been at least 6 metres (20 ft) long. According to Gregory S. Paul, it was about 8 metres (26 ft) long and weighed about 3,000 kilograms (6,600 lb).

Aralosaurini

Aralosaurini is a tribe of basal lambeosaurine hadrosaurs endemic to Eurasia. It currently contains Aralosaurus (from the Aral sea of Kazakhstan) and Canardia (from Toulouse, Southern France).

Blasisaurus

Blasisaurus is a genus of lambeosaurine hadrosaurid dinosaur from the Late Cretaceous. It is known from a partial skull and skeleton found in late Maastrichtian-age rocks of Spain. The type species is Blasisaurus canudoi, described in 2010 by Penélope Cruzado-Caballero, Xabier Pereda-Suberbiola and José Ignacio Ruiz-Omeñaca, a group of researchers from Spain.

Canardia

Canardia is an extinct genus of aralosaurin lambeosaurine dinosaur known from the Late Cretaceous Marnes d’Auzas Formation (late Maastrichtian stage) of Toulouse, Haute-Garonne Department, southern France. The type species Canardia garonnensis was first described and named by Albert Prieto-Márquez, Fabio M. Dalla Vecchia, Rodrigo Gaete and Àngel Galobart in 2013.

Elasmaria

Elasmaria is a clade of iguanodont ornithopods known from Cretaceous deposits in South America, Antarctica, and Australia.

Galleonosaurus

Galleonosaurus (meaning "galleon lizard" as the upper jaw bone resembles an upturned galleon) is a genus of basal ornithopod dinosaur from the Wonthaggi Formation of the Gippsland region of Victoria, Australia. The type and only species is G. dorisae, described by Herne et al. in 2019.

Jaxartosaurus

Jaxartosaurus is a genus of hadrosaurid dinosaur similar to Corythosaurus which lived during the Late Cretaceous. Its fossils were found in Kazakhstan.

Kazaklambia

Kazaklambia is an extinct genus of herbivorous lambeosaurine dinosaur known from the Late Cretaceous Dabrazinskaya Svita (Santonian stage) of southern Kazakhstan. It contains a single species, Kazaklambia convincens.Kazaklambia was first described in 1968 as a species of Procheneosaurus by Anatoly Konstantinovich Rozhdestvensky: Procheneosaurus convincens. The specific name refers to the fact that the specimen, the most complete dinosaur fossil ever discovered on Soviet territory, convincingly proved that dinosaurs could be found above the so-called "dinosaur horizon". After having for a time been referred to as Corythosaurus convincens, it was given its own genus in 2013 by Phil R. Bell and Kirstin S. Brink.Kazaklambia is known from a nearly complete skeleton of a juvenile missing only the snout, the front of the lower jaws, some dorsal vertebrae and end of the tail, holotype PIN 2230, found by G.A. Belenkiy in 1961. Although some studies considered it to be possibly synonymous with Jaxartosaurus aralensis, others found the species to be valid.Bell & Brink suggested that Kazaklambia is morphologically distinct from other Eurasian taxa and known juvenile lambeosaurines at a similar ontogenetic stage in having a prefrontal process of the postorbital with a thickened dome lateral to the frontal dome, doming of the nasal above and in front of the orbit, and a frontal length/width ratio of less than one.

Bell and Brink (2013) assigned Kazaklambia to the Lambeosaurinae, in a basal position. Morphometrics and morphological information suggest that Kazaklambia might be closely related to the basal lambeosaurines from Asia Amurosaurus and Tsintaosaurus, which was seen as proving an Asian origin of the Lambeosaurinae.

Laiyangosaurus

Laiyangosaurus ("Laiyang lizard") is a genus of saurolophine hadrosaurid from the Late Cretaceous of China. It is known from one species, L.youngi, found in the Laiyang Basin within the province of Shandong.

Lambeosaurinae

Lambeosaurinae is a group of crested hadrosaurid dinosaurs.

Lambeosaurini

Lambeosaurini, previously known as Corythosaurini, is one of four tribes of hadrosaurid ornithopods from the family Lambeosaurinae. It is defined as all lambeosaurines closer to Lambeosaurus lambei than to Parasaurolophus walkeri, Tsintaosaurus spinorhinus, or Aralosaurus tuberiferus, which define the other three tribes. Members of this tribe possess a distinctive protruding cranial crest. Lambeosaurins walked the earth for a period of around 12 million years in the Late Cretaceous, though they were confined to regions of modern day North America and Asia.

Lapampasaurus

Lapampasaurus is an extinct genus of hadrosaurid known from the Late Cretaceous Allen Formation (late Campanian or early Maastrichtian stage) of La Pampa Province, Argentina. It contains a single species, Lapampasaurus cholinoi.The generic name refers to the Argentine province of La Pampa. The specific name honours the late collector José Cholino. The material includes cervical, dorsal, sacral and caudal vertebrae, the forelimb girdle, and the partial hindlimb.

Pararhabdodon

Pararhabdodon (meaning "near fluted tooth" in reference to Rhabdodon) is a genus of tsintaosaurin hadrosaurid dinosaur, from the Maastrichtian-age Upper Cretaceous Tremp Formation of Spain. The first remains were discovered from the Sant Romà d’Abella fossil locality and assigned to the genus Rhabdodon, and later named as the distinct species Pararhabdodon isonensis in 1993. Known material includes assorted postcranial remains, mostly vertebrae, as well as maxillae from the skull. Specimens from other sites, including remains from France, a maxilla previously considered the distinct taxon Koutalisaurus kohlerorum, an additional maxilla from another locality, the material assigned to the genera Blasisaurus and Arenysaurus, and the extensive Basturs Poble bonebed have been considered at different times to belong to the species, but all of these assignments have more recently been questioned.

Initially, the material was thought to belong to a rhabdodontid dinosaur, or some other similar type of primitive iguanodontian. Later discoveries of additional material revealed its true nature as a hadrosaur. Its placement within the group remained controversial - in 1999 it was proposed it belonged to the subfamily Lambeosaurinae, making it the first known from the continent of Europe. Later studies questioned this, instead classifying it as a more primitive hadrosauroid. In 2009 evidence was put forward that it was indeed a lambeosaurine, and more specifically a close relative of Tsintaosaurus, a genus from China. This position has been consistently found since, and the group containing them was later named Tsintaosaurini.

Plesiohadros

Plesiohadros is an extinct genus of hadrosauroid dinosaur. It is known from a partial skeleton including the skull collected at Alag Teg locality, from the Campanian Djadochta Formation of southern Mongolia. The type species is Plesiohadros djadokhtaensis.

Prosaurolophus

Prosaurolophus (; meaning "before Saurolophus", in comparison to the later dinosaur with a similar head crest) is a genus of hadrosaurid (or duck-billed) dinosaur from the Late Cretaceous of North America. It is known from the remains of at least 25 individuals belonging to two species, including skulls and skeletons, but it remains obscure. Around 9 m (30 ft), its fossils have been found in the late Campanian-age Upper Cretaceous Dinosaur Park Formation in Alberta, and the roughly contemporaneous Two Medicine Formation in Montana, dating to around 75.5-74.0 million years ago. Its most recognizable feature is a small solid crest formed by the nasal bones, sticking up in front of the eyes.

The type species is P. maximus, described by American paleontologist Barnum Brown of the American Museum of Natural History in 1916. A second species, P. blackfeetensis, was described by Jack Horner of the Museum of the Rockies in 1992. The two species were differentiated mainly by crest size and skull proportions.

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 Tan Xichou ("H.C. Tan"). The specific epithet refers to China. In 2010 Gregory S. Paul estimated the length of Tanius at seven metres and the weight at two tonnes.

Tsintaosaurini

Tsintaosaurini is a tribe of basal lambeosaurine hadrosaurs native to Eurasia. It currently contains only Tsintaosaurus (from China) and Pararhabdodon (from Spain ).Koutalisaurus, also known from late Cretaceous Spain and formerly referred to Pararhabdodon

, may also be a tsintaosaurin because of its association with the latter genus; some recent work also suggests it may indeed be referrable to Pararhabdodon.

Xuwulong

Xuwulong is a genus of hadrosauroid dinosaur from the Early Cretaceous period. It lived during the early Cretaceous period (Aptian-Albian age) in what is now Yujingzi Basin in the Jiuquan area, Gansu Province of northwestern China. It is known from the holotype – GSGM F00001, an articulated specimen including a complete cranium, almost complete axial skeleton, and complete left pelvic girdle from Xinminpu Group. Xuwulong was named by You Hailu, Li Daqing and Liu Weichang in 2011 and the type species is Xuwulong yueluni.

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