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''Probactrosaurus'' (meaning "before '' Bactrosaurus''") is an early herbivorous hadrosauroid iguanodont
In 1959 and 1960 a Soviet-Chinese expedition uncovered the remains of a euornithopod in
''Probactrosaurus'' was a
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 ...
. It lived in China during the Late Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
period.
Discovery and species
In 1959 and 1960 a Soviet-Chinese expedition uncovered the remains of a euornithopod in Inner Mongolia
Inner Mongolia, officially the Inner Mongolia Autonomous Region, is an autonomous region of the People's Republic of China. Its border includes most of the length of China's border with the country of Mongolia. Inner Mongolia also accounts for ...
near Maortu. The type species
In 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 species that contains the biological type specimen( ...
is ''Probactrosaurus gobiensis'', described and named by A. K. Rozhdestvensky in 1966
Events January
* January 1 – In a coup, Colonel Jean-Bédel Bokassa takes over as military ruler of the Central African Republic, ousting President David Dacko.
* January 3 – 1966 Upper Voltan coup d'état: President Maurice Yaméogo is ...
. The generic name refers to Rozhdestvensky's hypothesis that ''Probactrosaurus'' would be the direct ancestor of ''Bactrosaurus'', a notion now discarded.
The specific name refers to the Gobi desert
The Gobi Desert ( Chinese: 戈壁 (沙漠), Mongolian: Говь (ᠭᠣᠪᠢ)) () is a large desert or brushland region in East Asia, and is the sixth largest desert in the world.
Geography
The Gobi measures from southwest to northeast ...
. The holotype
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...
specimen, PIN 2232/1, a partial skeleton with skull, was found in layers of the Dashuigou Formation. Another partial skeleton, PIN 2232-10, was found along with numerous other fragments.
In 1966 Rozhdestvensky also named a second species, ''Probactrosaurus alashanicus'', based on fragmentary material. Its specific name refers to the Alxa League
Alxa League or Ālāshàn League (; mn, , Mongolian Cyrillic. Алшаа аймаг) is one of 12 prefecture level divisions and 3 extant leagues of Inner Mongolia. The league borders Mongolia to the north, Bayan Nur to the northeast, Wuh ...
. In 2002 David B. Norman published a revision of the genus, in which he reported the holotype specimen of ''P. alshanicus'', the back of a skull, had been lost after being dispatched from Moscow
Moscow ( , US chiefly ; rus, links=no, Москва, r=Moskva, p=mɐskˈva, a=Москва.ogg) is the capital and largest city of Russia. The city stands on the Moskva River in Central Russia, with a population estimated at 13.0 million ...
to Beijing
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Beijing ( ; ; ), alternatively romanized as Peking ( ), is the capital of the People's Republic of China. It is the center of power and development of the country. Beijing is the world's most populous national capital city, with over 21 ...
. He concluded that the species was a synonym of ''P. gobiensis''.
In 1997 Lü Junchang named a third species, ''Probactrosaurus mazongshanensis'', based on holotype IVPP V.11333 found in 1992. The specific name refers to the Mazong Shan The Mǎzōng Shān () is a minor mountain range of Subei Mongol Autonomous County, Jiuquan, northern Gansu, China, between the Altay range to the north and the Qilian range to the south. The Mǎzōng Shān peak rises to 2584 m.
Climate
Mount ...
region. Today, this form is seen as more closely related to ''Equijubus
''Equijubus'' (; ''Mǎzōng'' meaning "horse mane" after the area Mǎzōng Mountain 马鬃山 in which it was found), is a genus of herbivorous hadrosauroid dinosaur from the Early Cretaceous ( Albian stage) of northwestern China.
Discovery ...
'' and '' Altirhinus'' rather than to ''P. gobiensis'' and is therefore commonly referred to as "''Probactrosaurus''" ''mazongshanensis''. It was moved to the new genus ''Gongpoquansaurus
''Gongpoquansaurus'' (meaning "Gongpoquan reptile") is an extinct genus of basal hadrosauroid dinosaur that was not formally named until 2014, while the name was a ''nomen nudum'' for many years previously. It is known from IVPP V.11333, a par ...
'' in 2014.
Description
''Probactrosaurus'' was a herbivorous
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
dinosaur. In 2010 Gregory S. Paul estimated its length at 5.5 metres (18 feet) and its weight at one tonne.Paul, G.S., 2010, ''The Princeton Field Guide to Dinosaurs'', Princeton University Press p. 292 ''Probactrosauurus'' was lightly built, with relatively long and slender arms and hands and only a small thumb spike. It had a narrow snout, an elongated lower jaw and tooth batteries, each consisting of a superimposed double row of flattened cheek teeth; a third row of replacement teeth was incipient. Probably predominantly quadrupedal, it shared some common features with the later duck-billed dinosaurs.
Classification
''Probactrosaurus'' was originally assigned by Rozhdestvenky to theIguanodontidae
Iguanodontidae is a family of iguanodontians belonging to Styracosterna, a derived clade within Ankylopollexia.
Characterized by their elongated maxillae, they were herbivorous and typically large in size. This family exhibited locomotive dyna ...
. Today it is seen as a basal
Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''.
Science
* Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure
* Basal (medicine), a minimal level that is nec ...
member of the Hadrosauroidea
Hadrosauroidea is a clade or superfamily of ornithischian dinosaurs that includes the "duck-billed" dinosaurs, or hadrosaurids, and all dinosaurs more closely related to them than to '' Iguanodon''. Their remains have been recovered in Asia, Euro ...
, relatively closely related to the Hadrosauromorpha
Hadrosauromorpha is a clade of iguanodontian ornithopods, defined in 2014 by David B. Norman to divide Hadrosauroidea into the basal taxa with compressed manual bones and a pollex, and the derived taxa that lack them. The clade is defined as al ...
.
See also
*Timeline of hadrosaur research
A timeline is a display of a list of events in chronological order. It is typically a graphic design showing a long bar labelled with dates paralleling it, and usually contemporaneous events.
Timelines can use any suitable scale representi ...
References
Hadrosaurs Late Cretaceous dinosaurs of Asia Iguanodonts Fossil taxa described in 1966 Taxa named by Anatoly Konstantinovich Rozhdestvensky Ornithischian genera {{ornithopod-stub