Expeditions into the
Gansu Province of northwestern China began with the
Sino-Swedish Expedition of 1930 to 1931, where discoveries of dinosaurs including the now-dubious early ceratopsian
Microceratops sulcidens. These discoveries were followed by occasional observations of dinosaur bones in the Houhongquan
Basin in the 1960s, and then the Gongpoquan Basin in 1986. Such observations led to the
China-Canada Dinosaur Project taking a reconnaissance trip to the Gongpoquan Basin in 1988, but no further expeditions were led until the
Sino-Japanese Silk Road Dinosaur Expedition of 1992 and 1993, led by Chinese paleontology
Dong Zhiming of the
Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) and Japanese paleontologst
Yoichi Azuma of the
Fukui Prefectural Dinosaur Museum (FPDM). The first description of many of the newly-discovered fossils, from Mazongshan area of Gansu and the
Turpan Basin of
Xinjiang, was in
1997 as part of a book on the Sino-Japanese Silk Road expedition, following 1992 and 1993 excavations as well as a 1996 display of the fossils in
Nagoya City Science Museum. One collection of these fossils, discovered in 1992 in a
sandstone in the Mazongshan area, was described as the new species of the
hadrosauroid Probactrosaurus,
P. mazongshanensis.
P. mazongshanensis was named in 1997 by Chinese paleontologist
Lü Junchang for a partial skull, the
holotype IVPP V. 11333, and a partial skeleton including almost all regions of the body, IVPP V. 11334.
Probactrosaurus mazongshanensis was found at the field locality IVPP 9208, within the
Early Cretaceous of the
Xinminbao Group in the Gongpoquan Basin. The Early Cretaceous deposits of the Gongpoquan Basin of the Xinminbao Group form two distinct
facies, with
P. mazongshanensis known from the upper grey beds. Carbon isotopes from the Xinminbao Group of Yujingzi Basin show sediments of the area are correlated to the
ocean anoxic event named the
Paquier Event, spanning the late
Aptian to early
Albian.
Radiometric dating of the
Xiagou Formation and
Zhonggou Formation elsewhere allows the sediments of the Yujingzi Basin to be identified, with the lower gray to green-gray
mudstones and
siltstones being the Xiagou Formation, while the red sandstones are the base of the Zhonggou and the upper grey sandstones. The upper grey beds, which are only found in the Gongpoquan Basin, are above the red beds, placing
P. mazongshanensis higher in the Zhonggou Formation with an early to mid-
Albian age. Following the initial description of
P. mazongshanensis, numerous other hadrosauroids were named from the Xinminbao Group of Mazongshan, including
Equijubus,
Jintasaurus, and
Xuwulong. These new taxa led to the questioning of the generic identity of
P. mazongshanensis, with it being interpreted as deserving a new
genus name. In
2014, Chinese paleontologists You Hailu, Li Daqing and American paleontologist
Peter Dodson reviewed
P. mazongshanensis, giving it the new name
Gongpoquansaurus. The genus name refers to the Gongpoquan Basin, with the holotype locality itself now being encompassed within the area Subei Gongpoquan Dinosaur Geopark of Gansu Province that was established in 2006. You and colleagues found that
Gongpoquansaurus was further from
hadrosaurids than the type species of
Probactrosaurus,
P. gobiensis. ==Classification==