Sinornithomimus Temporal range: Late Cretaceous, ~ | |
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Skeletal restorations of an adult (left) and juvenile (right) | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Clade: | † Ornithomimosauria |
Family: | † Ornithomimidae |
Genus: | † Sinornithomimus Kobayashi & Lü, 2003 |
Species: | †S. dongi |
Binomial name | |
†Sinornithomimus dongi Kobayashi & Lü, 2003 | |
Sinornithomimus is a genus of ornithomimid that lived in Asia during the Late Cretaceous period. The first remains were found in 1997, in the Late Cretaceous strata of the Ulansuhai Formation located at Alshanzuo Banner, Inner Mongolia Autonomous Region, Northern China.
The first fossil remains of Sinornithomimus were uncovered by Dong Zhiming in the Ulansuhai Formation as part of the Mongol Highland International Dinosaur Project in 1997. They contained at least fourteen skeletons found in close association, nine of which are nearly complete and relatively uncrushed. The find consisted of three sub-adult to adult specimens and eleven juveniles. The unweathered state of the bones, preserved in siltstone interspersed with layers of clay and the absence of evidence for post-mortem movement, argue for a catastrophic event that killed all the individuals present in the find simultaneously and instantaneously. [1]
The type species Sinornithomimus dongi was named and described by Yoshitsugu Kobayashi and Lü Junchang in 2003. The generic name means “Chinese bird mimic” while the specific descriptor honours Dong as the discoverer of the fossils. The holotype, IVPP-V11797-10, is one of the subadult skeletons. The other skeletons have been assigned as paratypes. [2]
A second expedition in 2001 at the same site led to the discovery of another fossilized herd of thirteen juveniles and subadults of Sinornithomimus. Their positioning suggest that they died together and over a short interval, likely after having become mired in the mud of a drying waterhole. The second discovery also largely consisted of nearly intact exemplars making Sinornithomimus the most completely known ornithomimid. [3] [4]
Sinornithomimus was a small ornithomimid measuring 2.5 m (8.2 ft) in length and weighing about 91 kg (201 lb) with a relatively short neck and head for a member of that group. [2] [5] Autapomorphies (unique derived traits) included the possession of a quadrate with a depression having within a smaller opening which is divided by a vertical sheet of bone; and a depression on the lateral side of the posterior process of the parietal bone. [2] [3]
Sinornithomimus was by the describers assigned to the Ornithomimidae. It was a basal ornithomimid that was considered by its describers a more derived form than Archaeornithomimus , [2] though more recent analyses reverse the situation. The structure of the hand is similar to that of Archaeornithomimus representing thus an intermediate between the "primitive" condition of the ornithomimosaur Harpymimus and the one of the more derived ornithomimids. Sinornithomimus renders some synapomorphies of ornithomimids plesiomorphic, while also differentiating Asian ornithomimid rhamphothecae from North American ones, based on maxillary vascular foramina found in the latter. [3]
The following cladogram follows that of Xu and colleagues in 2011: [6]
Ornithomimidae |
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The herbivory of this genus is supported by the rare presence of gastroliths, as such stones were found forming conspicuous masses in the stomach areas of the fossil skeletons. [7] This species was gregarious, which is corroborated by the arrangement of the fossil remains in a small bonebed with the juvenile individuals being approximately of the same age. This is furthermore supported by the increase of running ability as the animal progressed in its ontogeny, thus shown in the more cursorial proportions of the adults which possess relatively longer lower legs. It was assumed by the describers that adults protected themselves and their juveniles from predators by forming familial groups; in 2008 however a study concluded that the all juvenile herds suggest that immature individuals were left to fend for themselves in juvenile groups while adults preoccupied themselves with nesting or brooding. [2] [3]
Gallimimus is a genus of theropod dinosaur that lived in what is now Mongolia during the Late Cretaceous period, about seventy million years ago (mya). Several fossils in various stages of growth were discovered by Polish-Mongolian expeditions in the Gobi Desert of Mongolia during the 1960s; a large skeleton discovered in this region was made the holotype specimen of the new genus and species Gallimimus bullatus in 1972. The generic name means "chicken mimic", referring to the similarities between its neck vertebrae and those of the Galliformes. The specific name is derived from bulla, a golden capsule worn by Roman youth, in reference to a bulbous structure at the base of the skull of Gallimimus. At the time it was named, the fossils of Gallimimus represented the most complete and best preserved ornithomimid material yet discovered, and the genus remains one of the best known members of the group.
Anserimimus is a genus of ornithomimid theropod dinosaur, from the Late Cretaceous Period of what is now Mongolia. It was a lanky, fast-running animal, possibly an omnivore. From what fossils are known, it probably closely resembled other ornithomimids, except for its more powerful forelimbs.
Ornithomimosauria are theropod dinosaurs which bore a superficial resemblance to the modern-day ostrich. They were fast, omnivorous or herbivorous dinosaurs from the Cretaceous Period of Laurasia, as well as Africa and possibly Australia. The group first appeared in the Early Cretaceous and persisted until the Late Cretaceous. Primitive members of the group include Nqwebasaurus, Pelecanimimus, Shenzhousaurus, Hexing and Deinocheirus, the arms of which reached 2.4 m (8 feet) in length. More advanced species, members of the family Ornithomimidae, include Gallimimus, Struthiomimus, and Ornithomimus. Some paleontologists, like Paul Sereno, consider the enigmatic alvarezsaurids to be close relatives of the ornithomimosaurs and place them together in the superfamily Ornithomimoidea.
Struthiomimus, meaning "ostrich-mimic", is a genus of ornithomimid dinosaurs from the late Cretaceous of North America. Ornithomimids were long-legged, bipedal, ostrich-like dinosaurs with toothless beaks. The type species, Struthiomimus altus, is one of the more common, smaller dinosaurs found in Dinosaur Provincial Park; their overall abundance—in addition to their toothless beak—suggests that these animals were mainly herbivorous or omnivorous, rather than purely carnivorous. Similar to the modern extant ostriches, emus, and rheas, ornithomimid dinosaurs likely lived as opportunistic omnivores, supplementing a largely plant-based diet with a variety of small mammals, reptiles, amphibians, insects, invertebrates, and anything else they could fit into their mouth, as they foraged.
Deinocheirus is a genus of large ornithomimosaur that lived during the Late Cretaceous around 70 million years ago. In 1965, a pair of large arms, shoulder girdles, and a few other bones of a new dinosaur were first discovered in the Nemegt Formation of Mongolia. In 1970, this specimen became the holotype of the only species within the genus, Deinocheirus mirificus; the genus name is Greek for "horrible hand". No further remains were discovered for almost fifty years, and its nature remained a mystery. Two more complete specimens were described in 2014, which shed light on many aspects of the animal. Parts of these new specimens had been looted from Mongolia some years before, but were repatriated in 2014.
Garudimimus is a genus of ornithomimosaur that lived in Asia during the Late Cretaceous. The genus is known from a single specimen found in 1981 by a Soviet-Mongolian paleontological expedition in the Bayan Shireh Formation and formally described in the same year by Rinchen Barsbold; the only species is Garudimimus brevipes. Several interpretations about the anatomical traits of Garudimimus were made in posterior examinations of the specimen, but most of them were criticized during its comprehensive redescription in 2005. Extensive undescribed ornithomimosaur remains at the type locality of Garudimimus may represent additional specimens of the genus.
Archaeornithomimus is a genus of ornithomimosaurian theropod dinosaur that lived in Asia during the Late Cretaceous period, around 96 million years ago in the Iren Dabasu Formation.
Pelecanimimus is an extinct genus of basal ("primitive") ornithomimosaurian dinosaur from the Early Cretaceous of Spain. It is notable for possessing more teeth than any other member of the Ornithomimosauria, most of which were toothless.
The Bayan Shireh Formation is a geological formation in Mongolia, that dates to the Cretaceous period. It was first described and established by Vasiliev et al. 1959.
Ornithomimidae is an extinct family of theropod dinosaurs which bore a superficial resemblance to modern ostriches. Ornithomimids were fast, omnivorous or herbivorous dinosaurs known mainly from the Late Cretaceous Period of Laurasia, though they have also been reported from the Lower Cretaceous Wonthaggi Formation of Australia.
Nqwebasaurus is a basal coelurosaur and is the basal-most member of the coelurosaurian clade Ornithomimosauria from the Early Cretaceous of South Africa. The name Nqwebasaurus is derived from the Xhosa word Nqweba which is the local name for the Kirkwood district, and thwazi is ancient Xhosa for "fast runner". Currently it is the oldest coelurosaur in Africa and shows that basal coelurosaurian dinosaurs inhabited Gondwana 50 million years earlier than previously thought. The type specimen of Nqwebasaurus was discovered by William J. de Klerk who is affiliated with the Albany Museum in Grahamstown. It is the only fossil of its species found to date and was found in the Kirkwood Formation of the Uitenhage Group. Nqwebasaurus has the unofficial nickname "Kirky", due to being found in the Kirkwood.
The Nemegt Formation is a geological formation in the Gobi Desert of Mongolia, dating to the Late Cretaceous. The formation consists of river channel sediments and contains fossils of fish, turtles, crocodilians, and a diverse fauna of dinosaurs, including birds.
The Ulansuhai Formation is a geological formation in Inner Mongolia, north China. Dinosaur remains are among the fossils that have been recovered from the formation.
Beishanlong is a genus of giant ornithomimosaurian theropod dinosaur from the Early Cretaceous of China. It is the second-largest ornithomimosaur discovered, only surpassed by the related Deinocheirus.
Qiupalong is an extinct genus of ornithomimosaurian theropod that was discovered in the Late Cretaceous Qiupa Formation of Henan, China. The genus contains a single species, Q. henanensis, the specific epithet for which was named for the province of Henan. Uniquely, Qiupalong is one of the few Late Cretaceous non-avian dinosaurs known from both Asia and Laramidia. Specimens from Russia and Alberta have been referred to the genus without being assigned to the type species.
This timeline of oviraptorosaur research is a chronological listing of events in the history of paleontology focused on the oviraptorosaurs, a group of beaked, bird-like theropod dinosaurs. The early history of oviraptorosaur paleontology is characterized by taxonomic confusion due to the unusual characteristics of these dinosaurs. When initially described in 1924 Oviraptor itself was thought to be a member of the Ornithomimidae, popularly known as the "ostrich" dinosaurs, because both taxa share toothless beaks. Early caenagnathid oviraptorosaur discoveries like Caenagnathus itself were also incorrectly classified at the time, having been misidentified as birds.
This timeline of ornithomimosaur research is a chronological listing of events in the history of paleontology focused on the ornithomimosaurs, a group of bird-like theropods popularly known as the ostrich dinosaurs. Although fragmentary, probable, ornithomimosaur fossils had been described as far back as the 1860s, the first ornithomimosaur to be recognized as belonging to a new family distinct from other theropods was Ornithomimus velox, described by Othniel Charles Marsh in 1890. Thus the ornithomimid ornithomimosaurs were one of the first major Mesozoic theropod groups to be recognized in the fossil record. The description of a second ornithomimosaur genus did not happen until nearly 30 years later, when Henry Fairfield Osborn described Struthiomimus in 1917. Later in the 20th century, significant ornithomimosaur discoveries began occurring in Asia. The first was a bonebed of "Ornithomimus" asiaticus found at Iren Debasu. More Asian discoveries took place even later in the 20th century, including the disembodied arms of Deinocheirus mirificus and the new genus Gallimimus bullatus. The formal naming of the Ornithomimosauria itself was performed by Rinchen Barsbold in 1976.
Aepyornithomimus is a genus of ornithomimid theropod dinosaur from the Late Cretaceous Djadokhta Formation in Mongolia. It lived in the Campanian, around 75 million years ago, when the area is thought to have been a desert. The type and only species is A. tugrikinensis.
Oksoko is a genus of oviraptorid dinosaur from the Late Cretaceous of Asia, that lived in what is now the Nemegt Formation in Mongolia. It includes the type species Oksoko avarsan.