[D] Microhadrosaurus nanshiungensis [dG] [T]
Cretaceous Late Campanian Maastrichtian
Ornithischia Ornithopoda Hadrosauridae Nomina Dubia
Nanxiong Formation, Guandong, China
Genus - Typespecies
Dentary with teeth.
Dinosaurs from the Cretaceous of South China Zhiming Dong (Institute of Vertebrate Paleontology Paleoanthropology, Academia Sinica) From Mesozoic and Cenozoic Red Beds of South China Selected Papers from the \\\"Cretaceous-Tertiary Workshop,\\\" Nanxiong, Guangdong Province Edited by Institute of Vertebrate Paleontology, Paleoanthropology & Nanjing Institute of Paleontology Science Press, 1979 pp. 342-350
Translated By Will Downs Department of Geology Northern Arizona University August, 2002
In 1961, the Guangdong Provincial Office of Geology conducted field work in the Nanxiong Basin where they collected a partial pes that was diagnosed by Young et al. (1962) to belong to the ?Coelurosauria. This represented the first documentation of dinosaurs in the “Red Beds” of South China and indicated that they represented the Mesozoic, attracting much attention from geologists and paleontologists. Following the initial survey of the Red Beds, continuous regional reports of fragmentary dinosaurs were published, although systematic excavations were not conducted, and consequently the distribution and precise age were left unknown.
Under the great Proletarian Cultural Revolution, the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) formed the South China Red Beds Survey with associates from related departments, conducting consecutive research in the provinces of Guangdong, Anwei, Henan, Zhejiang, Guangxi, Hubei, and Jiangxi.
In addition to an abundant collection of Early Tertiary mammals, several dinosaur specimens were collected. In 1974, IVPP geologists continued research in the Nanxiong Basin, where they collected a set of relatively good specimens. This text is based upon these specimens and is an introduction to the dinosaurs from the South China Red Beds. The Nanxiong Basin is one of the numerous basins that produces dinosaurs from the South China Red Beds. In addition to the material collected in 1974, this text describes additional specimens that have been collected during the several years of Nanxiong fieldwork. All specimens were collected from the Nanxiong Formation.
Microhadrosaurus gen. nov.
Microhadrosaurus nanshiungensis gen. et sp. nov.
A rather small hadrosaur with a linear mandible, densely packed and planar dentition with vertical alveolae, and tooth count that does not exceed 45. The coronoid process is perpendicular to the mandible.
A 13.2 cm long midsection of a left mandible collected by the Guangdong Provincial Regional Survey. IVPP specimen #V4732.
The specimen is principally represented by a posterior dentary with linear dorsal and ventral margins, its lateral midsection is inflated, dorsal margin is thin, medioventral margin is thick, and the Meckelian groove penetrates anteriorly and gradually attenuates. The medial side is flatter than the general hadrosaurian condition, the dentition is densely packed, 19 perpendicular and parallel aligned dental rows are preserved, and the apex of the coronoid process is slightly expanded into a shovel-shape.
Comparison and discussion
It is appropriate to assign the specimen to the subfamily Hadrosaurinae based upon the flat and straight mandible and relatively low dentary, indicating that the mandible is rather narrow and thus, the cranium is correspondingly elongated. This is a relatively small individual, being probably only three meters in length, and representing the smallest species of hadrosaur known. It resembles the North American Hadrosaurus and Canadian Anatosaurus [Anatotitan] in its planar dentition and relatively densely packed tooth grooves, however the former are much larger. Despite there being only a single mandible, it is sufficient to recognize that it represents a new taxon and is thus erected as Microhadrosaurus nanshiungensis gen. et sp. nov.
Source: Polyglot Paleontologist