''Charonosaurus'' ( ; meaning " Charon's lizard") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

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 ...

whose fossils were discovered by Godefroit, Zan & Jin in 2000 on the south bank of the Amur River, dividing China from

Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eig ...

. It is monotypic, consisting of the species ''C. jiayinensis''.

Description

''Charonosaurus'' is a very large lambeosaurine

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 incl ...

, estimated around in length and in body mass.Holtz, Thomas R. Jr. (2012) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages,'
Winter 2011 Appendix.
/ref> It is known from a partial skull (Holotype: CUST J-V1251-57 (Changchun University of Sciences and Technology, Changchun,

Jilin Province Jilin (; alternately romanized as Kirin or Chilin) is one of the three provinces of Northeast China. Its capital and largest city is Changchun. Jilin borders North Korea ( Rasŏn, North Hamgyong, Ryanggang and Chagang) and Russia (Prim ...

, China) found in the Late Maastrichtian Yuliangze Formation, west of Jiayin village, Heilongjiang Province, northeastern China. Adult and juvenile hadrosaur remains discovered in the same area and formation likely represent the same taxon and supply information on most of the

postcrania Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated sk ...

l skeleton; the femur length was up to 1.35 m (4.5 ft). The partial skull resembles that of '' Parasaurolophus'' and probably had a similar long, backward-projecting hollow crest, indicated by the highly modified dorsal surface of the

frontal bone The frontal bone is a bone in the human skull. The bone consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, pa ...

s. ''Charonosaurus'' is one of the largest hadrosaurs currently known from Asia and indicates that lambeosaurines survived until the very end of the Cretaceous (lambeosaurines are not known from the Late Maastrichtian in North America).

History of Discovery

The remains of ''Charonosaurus'' come from large bonebeds (bone deposits) discovered since 1975 during excavations by several Chinese institutions around the city of Jiayin on the Amur River. The holotype material (specimen number CUST J-V1251-57), a fragmentary skull, was described as ''Charonosaurus jiayinensis'' by Pascal Godefroit, Shuqin Zan and Liyong Jin in 2000. The genus name is derived from Charon, the ferryman from

Greek mythology A major branch of classical mythology, Greek mythology is the body of myths originally told by the ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the origin and nature of the world, the lives and activities ...

who carried the dead across the dead river Acheron (or Styx), and the ancient Greek word ''sauros'' (lizard). The specific epiteth ''jiayinensis'' refers to the type locality (site) Jiayin. Stratigraphically the finds are from the Yuliangze Formation. The first finds from this formation were recovered in the summers of 1916 and 1917 by excavations of the Russian Geological Committee. Among them are bones of hadrosaurids described by Anatoly Riabinin as ''Manchurosaurus amurensis''. Furthermore, Riabinin assigned another find, a very fragmentary ischium, to hadrosaurids and named it ''Saurolophus krystofovici''. Both names are nowadays considered as nomina dubia.

Phylogeny

A cladistic analysis in 2000 by Pascal Godefroit, Shuqin Zan and Liyong Jin based on 33 skull, tooth, and postcranial features shows that ''Charonosaurus jiayinensis'' could be phylogenetically more closely related to '' Parasaurolophus'' than to any other lambeosaurine. Characteristics that cannot be directly determined on the available bones were not included in the analysis. ''Eolambia'' and ''Tsintaosaurus'' were also not included in the analysis because these taxa are in need of revision according to Godefroit et al. The following phylogeny was conducted by Penélope Cruzado-Caballero ''et al''. in 2013.

Taphonomy

In the Yuliangze Formation near the village of Jiayin, bone beds were discovered scattered over several tens of square meters, consisting mostly of bones of ''Charonosaurus jiayinensis''. These bone beds contain numerous skeletons of both young and adult animals. They are out of anatomical alignment and intermingled. Long bones are oriented in one direction and the vertebral arches, spinous processes and transverse protrusions of the vertebrae (the apophyses) are broken off. These taphonomic features indicate that the thanatocoenosis formed in a river or stream environment with relatively strong currents, causing dinosaur carcasses to be concentrated and piled up at a low point in the landscape at the time. The bone beds consist of about 90% lambeosaurine fossils. Bones of ankylosaurs, theropods, turtles, and crocodiles make up the remaining ten percent. The bones of the lambeosaurines of Jiayin belong to only one species, ''Charonosaurus jiayinensis'', and there is no evidence that it lived with any other species of lambeosaurine in this restricted area. The abundance of ejected teeth from carnivorous dinosaurs shows that carcasses of ''Charonosaurus'' were torn up and consumed by predators and scavengers and/or that ''Charonosaurus'' was killed by these predators on hunts along a river.

Palaeoecology

''Charonosaurus jiayinensis'' is only known from the site at Jiayin. The

thanatocoenosis Thanatocoenosis (from Greek language ''thanatos'' - death and ''koinos'' - common) are all the embedded fossils at a single discovery site. This site may be referred to as a death assemblage. Such groupings are composed of fossils of organisms which ...

of the type locality of this species further consists of an unidentified hadrosaurine,"Wu, W.-H., Godefroit, P., & Han, J.-X., 2010. A hadrosaurine dentary from Upper Cretaceous of Jiayin, Heilongjiang. Global Geology 29(1): 1-5 the lambeosaurine '' Amurosaurus'', an unidentified

ankylosaurian Ankylosauria is a group of herbivorous dinosaurs of the order Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms, similar to turtles. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. ...

, the

tyrannosaurid Tyrannosauridae (or tyrannosaurids, meaning "tyrant lizards") is a family of coelurosaurian theropod dinosaurs that comprises two subfamilies containing up to thirteen genera, including the eponymous ''Tyrannosaurus''. The exact number of genera ...

Tarbosaurus bataar ''Tarbosaurus'' ( ; meaning "alarming lizard") is a genus of tyrannosaurid dinosaur that flourished in Asia about 70 million years ago, at the end of the Late Cretaceous Period (geology), Period, considered to contain a single known species, ' ...

'', unidentified tortoises, turtles of the species '' Amuremys planicostata'' and unidentified crocodiles. The Blagoveschensk thanatocoenosis (Udurchukan Formation, Tsagayan Group) contains, in addition to hadrosaurids, an unidentified

titanosaur Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thr ...

,Mannion, P.D., Upchurch, P., Barnes, R. N. and Mateus, O. (2013). Osteology of the Late Jurassic Portuguese sauropod dinosaur Lusotitan atalaiensis (Macronaria) and the evolutionary history of basal titanosauriforms. Zoological Journal of the Linnean Society 168:98-206, DOI:10.1111/zoj.12029 unidentified theropods,Godefroit, P., Bolotsky, Y.L., and Van Itterbeeck, J. 2004b. The lambeosaurine dinosaur Amurosaurus riabinini, from the Maastrichtian of Far Eastern Russia. Acta Palaeontologica Polonica 49: 585–618. unidentified turtles,Bolotsky, Y. L. and Godefroit, P. (2004). A new hadrosaurine dinosaur from the Late Cretaceous of Far Eastern Russia. Journal of Vertebrate Paleontology 24(2): 351–365. unidentified Nodosauridae, and unidentified crocodiles.

References

Lambeosaurines Late Cretaceous dinosaurs of Asia Fossil taxa described in 2000 Taxa named by Pascal Godefroit Ornithischian genera {{ornithopod-stub