''Mandschurosaurus'' (meaning "lizard from

Manchuria Manchuria is an exonym (derived from the endo demonym " Manchu") for a historical and geographic region in Northeast Asia encompassing the entirety of present-day Northeast China (Inner Manchuria) and parts of the Russian Far East (Outer Manc ...

") is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

hadrosaur Hadrosaurids (), 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 family, which includ ...

s based on material from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger 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 ''creta'', the ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

and possibly also the

Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pro ...

Laos Laos (, ''Lāo'' )), officially the Lao People's Democratic Republic ( Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ, French: République démocratique populaire lao), is a socialist ...

. It was the first

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 ...

named from

, and a mounted skeleton based on the holotype of ''M. amurensis'' is on display at the Central Geological and Prospecting Museum in

St. Petersburg Saint Petersburg ( rus, links=no, Санкт-Петербург, a=Ru-Sankt Peterburg Leningrad Petrograd Piter.ogg, r=Sankt-Peterburg, p=ˈsankt pʲɪtʲɪrˈburk), formerly known as Petrograd (1914–1924) and later Leningrad (1924–1991), i ...

; however, much of the skeleton is

plaster Plaster is a building material used for the protective or decorative coating of walls and ceilings and for Molding (decorative), moulding and casting decorative elements. In English, "plaster" usually means a material used for the interiors of ...

Discovery and naming

The holotype of ''M. amurensis'' (IVP AS coll.), the only valid species within the genus, is based on a poorly preserved and incomplete skeleton collected by

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

n scientists in 1914 from the banks of the

Amur River The Amur (russian: река́ Аму́р, ), or Heilong Jiang (, "Black Dragon River", ), is the world's List of longest rivers, tenth longest river, forming the border between the Russian Far East and Northeast China, Northeastern China (Inne ...

in a layer of the

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from ...

-aged

Yuliangze Formation The Yuliangze Formation, or Yuliangzi Formation, is a geological formation in Heilongjiang, China whose strata date back to the early-middle Maastrichtian. Dinosaur remains are among the fossils that have been recovered from the formation.Weishampe ...

and the remains represent a large hadrosaurid. ussian/ref> The holotype material was initially referred to the genus ''"

Trachodon ''Trachodon'' (meaning "rough tooth") is a dubious genus of hadrosaurid dinosaur based on teeth from the Campanian-age Upper Cretaceous Judith River Formation of Montana, U.S.Leidy, J. (1856). "Notice of remains of extinct reptiles and fishes, d ...

"'' (a ''

nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium'' it may be impossible to determine whether a s ...

'') as ''T. amurense'' by Riabinin (1925),Riabinin, A.N. (1925). A mounted skeleton of the gigantic reptile ''Trachodon amurense'', nov. sp. ''Izvest. Geol. Kom.'' 44(1):1-12. ussian/ref> but was later reassigned to a new genus by Riabinin (1930). The holotype of ''M. laosensis'', which is based mainly on an ilium and other fragmentary remains, comes from the

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), a ...

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 ± 0.9 M ...

-aged

Grès supérieurs Formation The Grès supérieurs Formation (French for "Upper sandstone") is a geological Formation (geology), formation in Laos whose strata date back to the Aptian to Albian stages of the Early Cretaceous. Dinosaur remains are among the fossils that have b ...

and was named by Hoffet (1944).J.-H. Hoffet. (1944). Description of the most characteristic bones belonging to Avipelvians from the Senonian of Lower Laos. ''Minutes of the Sessions of the Council for Scientific Research of Indochina'' 1944:179-186

Description

''M. amurensis'' would likely have reached up to when fully grown.

Classification

There has been some debate regarding the validity of this genus. Brett-Surman (1979) first considered it a ''

'', though some later workers have continued to see it as a valid taxon (Chapman et Brett Surman, 1990,Chapman R. et Brett-Surman M. K. (1990). Morphometric observations on hadrosaurid ornithopods. in Carpenter K. et Currie, P. J. (eds.), ''Dinosaur Systematics: Perspectives and Approaches'', Cambridge University Press, Cambridge 163-177. for example). Most recently,

Horner Horner is an English and German surname that derives from the Middle English word for the occupation ''horner'', meaning horn-worker or horn-maker, or even horn-blower. People *Alison Horner (born 1966), British businesswoman * Arthur Horner (dis ...

''et al.'' (2004) listed the type species as a ''nomen dubium'' in the second edition of ''

The Dinosauria ''The Dinosauria'' is an extensive book on dinosaurs, compiled by David B. Weishampel, Peter Dodson, and Halszka Osmólska. It has been published in 2 editions, with the first edition published in 1990, consisting of material from 23 scientists.B ...

''.Horner J., Weishampel D. B., et Forster C. A. (2004). Chapter Twenty: Hadrosauridae. in ''The Dinosauria'' (2nd edition), Weishampel D. B., Dodson P., and Osmólska H., editors. University of California Press. Over the years, three species have been placed within this genus: ''Mandschurosaurus amurensis'', ''M. mongoliensis'', and ''M. laosensis''. Brett-Surman (1979) considered ''M. mongoliensis'' a distinct genus, which he named ''

Gilmoreosaurus ''Gilmoreosaurus'' (meaning "Charles Whitney Gilmore's lizard") is the name given to a genus of dinosaur from the Cretaceous of Asia. The type species is ''Gilmoreosaurus mongoliensis''. It is believed to be a hadrosaur or iguanodont from the Ire ...

'' and Horner ''et al.'' (2004) considered ''M. laosensis'' a ''nomen dubium''; This leaves only Riabinin's original species, ''M. amurensis'', as a possibly valid taxon. Within

Ornithopoda Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (), that started out as small, bipedal running grazers and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world ...

, ''Mandschurosaurus'' is most often placed within

Hadrosauridae Hadrosaurids (), 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 family, which includ ...

as a ''nomen dubium''.

Gallery

Mandschurosaurus Amurensis..2H1A0401WI.jpg, Reconstructed ''M. amurensis'' skeleton in outdated tripod-pose, VSEGEI Museum,

References

{{Taxonbar, from=Q1076898 Late Cretaceous dinosaurs of Asia Hadrosaurs Fossil taxa described in 1930 Ornithischian genera

Discovery and naming

Description

Classification

Gallery

See also

References