Amurosaurus

Live reconstruction of Amurosaurus

• Eastern Russia ( at Blagoveshchensk, Udurchukan Formation)

• Amurosaurus riabinini

Amurosaurus ( " lizard from the Amur region " ) is a dinosaur from the family of Hadrosauridae ( duck-billed dinosaurs), which is counted to the Ornithischia ( bird Beck dinosaurs).

The remains - an incomplete skull and another, postcraniales ( no skull ) Material - comes from a single, the Upper Cretaceous (late Maastrichtian ) attributable bone bed from the Amur region of eastern Russia. There is an up to eight meters long basal Lambeosaurinen who was like his relatives an herbivore (plant -eater ) and probably quadrupedal and bipedal running. The only known species of this genus is Amurosaurus riabinini.

Location and History Fund

The Amurosaurus Fund

In 1984, on the outskirts of the city of Blagoveshchensk, discovered on the Russian side of the Amur River, a large bonebed, which had already released several hundred bones in 1991 on a 200 square-meter excavation area. Much of the bones belonged to dinosaurs Lambeosaurinen, although isolated Theropodenzähne - and bite marks on the Lambeosaurinen Bones - were discovered, suggesting predators or scavengers. A small portion of the bone ( interconnected left maxilla ( upper jaw bone) and the lower jaw bone; holotype um 1/12) was described by Bolotsky and Kurzanov in 1991 in a brief description as Amurosaurus riabinini. The Artepitheth riabinini honors the paleontologist Anatoly Riabinin, who led the first Russian dinosaur expeditions in this region (see below). However, the remaining bone, which were mainly juvenile Amurosaurus were not described. In the aftermath Amurosaurus found among paleontologists little attention, there was a detailed description of all previously discovered bones ( Godefroit, Bolotsky and Itter Beeck ) by the year 2004.

Geologically belong to the layers of the discovery site for Udurchukan lineup, which forms the lower part of the Tsagayan Group. The fossil -bearing sediments consist of greenish, granular clay. At the time these sediments were together with the bones in a floodplain or a river. The unconnected bones are well preserved - even fragile bones of the skull are present - and not by size. This suggests that the bones were transported from the water only a short distance.

Other finds from the Amur region

In the vicinity of the Amur River - which forms on a long stretch the border between Russia and China - dinosaur fossils have been discovered in 1902 - mostly Hadrosauriden bone. The first known discovery consists of isolated bones that were found near the village of Jiayin on the Chinese side. In the years 1916 and 1970, more bone came during excavations of the Russian Committee for Geology in the vicinity of Jiayin to days. Anatoly Riabinin it placed the Hadrosauridae and described two new species, Trachodon amurense and Saurolophus krystofovici which today but due to the very fragmentary remains as Nomia Dubia ( doubtful) are classified. Godefroit et al. (2000, 2001) described another species from Jiayin: Charonosaurus jiayinensis. Dinosaur fossils from the Russian side were first discovered in 1957. A recent discovery in the Russian Amur region, next to the Amurosaurus bone bed in Blagoveshchensk, a locality in Kundur. This was in addition to other bones found an almost complete, provided with a large head crest, Hadrosauriden skeleton, which was described in 2003 as Olorotitan arharensis ( Godefroit, Bolotsky and Alifanov ).

Description and differentiation from other species

The skeleton is almost completely known, which is one of the best-known Russian Amurosaurus dinosaurs. However, the top of the skull and the " duckbill " ( Premaxillare and pre- dentary ) is missing, and a bone comb, as it occurs in other Lambeosaurinen in some bizarre forms, was not found. However, the skull bones are built so that they would support a comb - so you can assume that this animal was wearing a comb. In reconstructions Amurosaurus is usually depicted with a slightly smaller bone crest.

The skeleton differs by many autapomorphies of the other Lambeosaurinen - including, for example, the extended S- shaped upper arm bone ( ulna and radius). Of the other two, known from the Amur region Lambeosaurinen from the Maastrichtian, Charonosaurus ( Yuliangze Formation) and Olorotitan ( Udurchukan Formation) to Amurosaurus clearly identifiable: from 22 major skeletal features can be viewed differently between Amurosaurus and Charonosaurus 14 as significant be. Between Amurosaurus and Olorotitan the differences are small (only six features ), but this is attributed to the fact that each different parts of the skull are preserved.

System

Amurosaurus is classified within the subfamily Lambeosaurinae which forms together with the Hadrosaurinae family Hadrosauridae. Within the Lambeosaurinae there are two sub-groups - the Parasaurolophini ( Charonosaurus and Parasaurolophus ) and the Lambeosaurini ( Corythosaurus, Hypacrosaurus, Olorotitan, Lambeosaurus and Nipponosaurus ). Jaxartosaurus and Tsintaosaurus apply due to some more primitive skull features as more basal taxa. Also Amurosaurus is one of the more basal species, but is more modern than Jaxartosaurus and Tsintaosaurus and is the two subgroups as sister taxon opposite. The fact that all basal Lambeosaurinae originate from Asia, led to the theory that this subfamily originated in Asia and later spread to North America.

Tsintaosaurus

Jaxartosaurus

Amurosaurus

Parasaurolophini ( Parasaurolophus, Charonosaurus )

Lambeosaurini (eg Lambeosaurus, Corythosaurus, Olorotitan )

Hadrosaurinae