Gigantoraptor

Gigantoraptor is a genus of giant oviraptorosaurian theropod dinosaur.[2]

Gigantoraptor
Temporal range: Late Cretaceous, 85–70.6 Ma
[1]
Gigantoraptor
Reconstructed Gigantoraptor skeleton with Oviraptor (below), in Japan
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Family: Caenagnathidae
Genus: Gigantoraptor
Xu et al., 2007
Species:
G. erlianensis
Binomial name
Gigantoraptor erlianensis
Xu et al., 2007

Description

Gigantoraptor size
Size of the type specimen and a potential egg compared to a human

It was clear to Xu et al. that Gigantoraptor belonged to the Oviraptorosauria, a group named after Oviraptor, but compared to other known members, Gigantoraptor was much larger, approximately three times as long and 35 times more massive than the heaviest earlier discovered oviraptorosaurid Citipati.[3] Xu et al. estimated the length at 8 metres (26 ft) and the weight at 1400 kilogrammes.[2] In 2010, Gregory S. Paul even gave an estimate of two tonnes (2.2 tons).[4]

The toothless lower jaws of Gigantoraptor are fused into a broad shovel-like mandibula. They indicate that the unknown skull was over half a metre long and toothless also, probably equipped with a horny beak. The front tail vertebrae have very long neural spines and are heavily pneumaticised with deep pleurocoels. The middle section of the relatively short tail is somewhat stiffened by long prezygapophyses. The back tail vertebrae are lightened by spongeous bone. The front limb is rather long because of an elongated slender hand. The humerus is bowed outwards to an exceptionally large extent and has a very rounded head. The first metacarpal is very short and carries a strongly diverging thumb. The hindlimb is also long because of an elongated lower leg. The thighbone is relatively slender and short with a distinct head and neck. The foot is robust with large and strongly curved toe claws.[2]

Gigantoraptor BW
Life restoration

No direct evidence of feathers was preserved with the skeleton, but Xu et al. (2007) discussed their likely presence on Gigantoraptor. They admitted that despite Gigantoraptor being a member of the Oviraptorosauria, a group that includes the feathered species Caudipteryx and Protarchaeopteryx, it might have been "naked" because it is three hundred times as massive as these species, and very large animals may rely more on mass for temperature regulation, losing the insulating coverings found on their smaller relatives. However, they suggested that at least arm feathers were probably still present on Gigantoraptor, since their primary functions, such as display and covering the eggs while brooding, are not related to the regulation of body heat.[2]

Discovery and naming

Gigantoraptor claw
Claw

In a quarry at Saihangaobi, in Sonid Left Banner (Inner Mongolia), numerous remains of the sauropod Sonidosaurus have been uncovered since 2001. Chinese paleontologist Xu Xing was asked to reenact the discovery of Sonidosaurus in April 2005 for a Japanese documentary. Xu obliged them by digging out a thighbone. As he wiped the bone clean, he suddenly realized it was not from a sauropod, but from an unidentified theropod in the size class of Albertosaurus. He then stopped the filming to secure the serendipitous find. This way, the discovery of the Gigantoraptor holotype fossil was documented on film.

In 2007, the type species Gigantoraptor erlianensis was named and described by Xu, Tan Qingwei, Wang Jianmin, Zhao Xijin and Tan Lin. The generic name is derived from Latin gigas, gigantis, "giant" and raptor, "seizer". The specific name refers to the Erlian Basin.[2]

The only known type specimen, LH V0011, was discovered in 2005 in the Iren Dabasu Formation, Erlian basin, in Inner Mongolia. The age of the Iren Dabasu formation is controversial; based on ostracods, Godefroit suggested the unit was equivalent to the Nemegt Formation, or about 70 Ma, though some vertebrate remains suggest an older Santonian age, between 84 and 86 Ma. It consists of the incomplete and disassociated remains of a single subadult individual, a partial skeleton lacking the cranium but including the lower jaw, a single neck vertebra, most of the back and tail and the majority of the frontlimb and hindlimb elements.[2]

Classification

In 2007, Xu et al. assigned Gigantoraptor to the Oviraptoridae, in a basal position. The anatomy of Gigantoraptor includes the diagnostic features of the Oviraptorosaurs. However, it also includes several features found in more derived eumaniraptoran dinosaurs, such as a frontlimb/hindlimb ratio of 60%, a lack of expansion of the distal scapula and the lack of a fourth trochanter on the thighbone. Despite its size, Gigantoraptor would thus have been more bird-like than its smaller oviraptorosaurian relatives.[2]

Gigantoraptor elrianensis skeleton
Hind view of reconstructed skeleton

In 2010, a second analysis of Gigantoraptor relationships found it to be a member of the Caenagnathidae rather than an oviraptorid.[5] Phylogenetic analysis conducted by Lamanna et al. (2014), supported that Gigantoraptor was a basal caenagnathid.[6] The cladogram below follows an analysis by Longrich et al. in 2013, which found Gigantoraptor to be a Caenagnathid.[7]

Caenagnathidae

Microvenator celar

unnamed

Gigantoraptor erlianensis

unnamed

Caenagnathasia martinsoni

Elmisaurus rarus

Caenagnathinae

Leptorhynchos elegans

Leptorhynchos gaddisi

Hagryphus giganteus

unnamed

Chirostenotes pergracilis

Caenagnathus collinsi

Anzu wyliei

Paleobiology

Babylouiethedinosaur
Embryo nicknamed "Baby Louie", belonging to the related genus Beibeilong, Children's Museum of Indianapolis

The diet of Gigantoraptor is uncertain. Although some oviraptorosaurs, such as Caudipteryx and Incisivosaurus, are thought to have been mostly herbivorous, Gigantoraptor had long hind legs with proportions that allowed for fast movement (it was probably more nimble than the larger and less agile Tarbosaurus), and large claws, a combination that is not usually found in herbivores of this size. Paul suggested that Gigantoraptor was also a herbivore and used its speed to escape predators.[4] The preserved jaw for Gigantoraptor also indicates that the theropod had a shearing bite, possibly for cutting through plants (or potentially meat).[8] This is comparable to other caenagnathids and contrasting with the jaws of oviraptorids, whose jaws seem better suited for crushing food.[9]

The specimen has advanced ossification and growth rings in the fibula that indicate it was likely eleven years of age when it died. It appears to have reached an early young adult stage at age seven, and probably would have grown much larger when it reached the adult stage. This indicates a growth rate that is faster than in most large non-avian theropods.[2]

The existence of giant oviraptorosaurians, such as Gigantoraptor, explains several earlier Asian finds of very large, up to 53 centimetres long, oviraptorosaurian eggs, assigned to the oospecies Macroelongatoolithus carlylensis. These were laid in enormous rings with a diameter of three metres.[4] The presence of Macroelongatoolithus in North America indicates that gigantic oviraptorosaurs were present there as well, though no fossil skeletal remains have been found.[10]

See also

References

  1. ^ "Fossilworks Gigantoraptor".
  2. ^ a b c d e f g h Xu, X.; Tan, Q.; Wang, J.; Zhao, X.; Tan, L. (2007). "A gigantic bird-like dinosaur from the Late Cretaceous of China". Nature. 447 (7146): 844–847. doi:10.1038/nature05849. PMID 17565365.
  3. ^ "Remains of giant bird-like dinosaur unveiled". CBC News. 13 June 2007. Retrieved 29 October 2011.
  4. ^ a b c Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 153
  5. ^ Nicholas R. Longrich, Philip J. Currie, Dong Zhi-Ming (2010). "A new oviraptorid (Dinosauria: Theropoda) from the Upper Cretaceous of Bayan Mandahu, Inner Mongolia". Palaeontology. 53 (5): 945–960. doi:10.1111/j.1475-4983.2010.00968.x.CS1 maint: Uses authors parameter (link)
  6. ^ Lamanna MC, Sues H-D, Schachner ER, Lyson TR (2014) "A New Large-Bodied Oviraptorosaurian Theropod Dinosaur from the Latest Cretaceous of Western North America." PLoS ONE 9(3): e92022. doi:10.1371/journal.pone.0092022
  7. ^ Longrich, N. R.; Barnes, K.; Clark, S.; Millar, L. (2013). "Caenagnathidae from the Upper Campanian Aguja Formation of West Texas, and a Revision of the Caenagnathinae". Bulletin of the Peabody Museum of Natural History. 54: 23–49. doi:10.3374/014.054.0102.
  8. ^ Waisum Ma, Junyou Wang, Michael Pittman, Qingwei Tan, Lin Tan, Bin Guo & Xing Xu (2017). Functional anatomy of a giant toothless mandible from a bird-like dinosaur: Gigantoraptor and the evolution of the oviraptorosaurian jaw. Scientific Reports 7, Article number: 16247 (2017). doi:10.1038/s41598-017-15709-7
  9. ^ Ma, W; Wang, J; Pittman, M; Tan, Q; Tan, L; Guo, B; Xu, X (2017). "Functional anatomy of a giant toothless mandible from a bird-like dinosaur: Gigantoraptor and the evolution of the oviraptorosaurian jaw". Scientific Reports. 7 (1): 16247. doi:10.1038/s41598-017-15709-7. PMC 5701234. PMID 29176627.
  10. ^ Simon, D. J. (2014). "Giant Dinosaur (theropod) Eggs of the Oogenus Macroelongatoolithus (Elongatoolithidae) from Southeastern Idaho: Taxonomic, Paleobiogeographic, and Reproductive Implications." (Doctoral dissertation, Montana State University, Bozeman).

External links

Anzu wyliei

Anzu (named for Anzû, a feathered demon in ancient Mesopotamian mythology) is a genus of chirostenotine dinosaur from the late Cretaceous (66 million years ago) of North Dakota and South Dakota, US. The type species is Anzu wyliei.

In 2015, the International Institute for Species Exploration names it as one of the "Top 10 New Species" for new species discovered in 2014.

Beibeilong

Beibeilong is an extinct genus of oviraptorosaurian dinosaur. The genus contains a single species B. sinensis, named in 2017 by Pu and colleagues based on a nest with a possible embryo (nicknamed "Baby Louie") and eggs. It was similar to but more basal than Gigantoraptor, and may have been of similar size as an adult. This result was consistently recovered by phylogenetic analyses incorporating ontogenetically variable characteristics, which led Pu et al. to conclude that they were distinct taxa.

Caenagnathasia

Caenagnathasia ('recent jaw from Asia') is a small caenagnathid oviraptorosaurian theropod from the Late Cretaceous of Uzbekistan.

Caenagnathidae

Caenagnathidae is a family of bird-like maniraptoran theropod dinosaurs from the Late Cretaceous of North America and Asia. They are a member of the Oviraptorosauria, and close relatives of the Oviraptoridae. Like other oviraptorosaurs, caenagnathids had specialized beaks, long necks, and short tails, and would have been covered in feathers. The relationships of caenagnathids were long a puzzle. The family was originally named by Charles Hazelius Sternberg in 1940 as a family of flightless birds. The discovery of skeletons of the related oviraptorids revealed that they were in fact non-avian theropods, and the discovery of more complete caenagnathid remains revealed that Chirostenotes pergracilis, originally named on the basis of a pair of hands, and "Ornithomimus" elegans, named from a foot, were caenagnathids as well.

Caenagnathoidea

Caenagnathoidea ("recent jaw forms") is a group of advanced oviraptorosaurian dinosaurs from the Cretaceous Period of what are now Asia and North America. They are distinct for their characteristically short, beaked, parrot-like skulls, often with bony crests atop the head. They ranged in size from Caudipteryx, which was the size of a turkey, to the 8 meter long, 1.4 ton Gigantoraptor. The group (along with all maniraptoran dinosaurs) is close to the ancestry of birds. The most complete specimens have been found in Asia, representing members of the sub-group Oviraptorinae. Notable but fragmentary remains are also known from North America, almost all of which belong to the subgroup Elmisaurinae.The earliest definitive caenangnathoid is Microvenator celer, which dates to the late Aptian age of the early Cretaceous period, though the slightly earlier Caudipteryx from the lower Yixian Formation of China, may also be a member of this group.

Caenagnathus

Caenagnathus ('recent jaw') is a genus of caenagnathid oviraptorosaurian dinosaur from the late Cretaceous (Campanian; ~75 million years ago). It is known from partial remains including lower jaws, a tail vertebra, hand bones, and hind limbs, all found in the Dinosaur Park Formation of Alberta, Canada. Caenagnathus weighted about a maximum of 96 kg (212 lb).

Dinosaur Island (Sea World)

Dinosaur Island was an animatronic dinosaur themed attraction at Sea World on the Gold Coast, Australia. The attraction was manufactured by Canadian company Dinosaurs Unearthed and opened on 16 June 2012.

Dinosaur Revolution

Dinosaur Revolution is a four-part American nature documentary produced by Creative Differences. It utilizes computer-generated imagery to portray dinosaurs and other animals from the Mesozoic era. The program was originally aired on the Discovery Channel and Science.

Dinosaur Revolution was released to mixed reviews, with some citing the quality of its animation and a lack of seriousness in its tone as reasons for criticism. It was, however, praised for its educational content and general energy.

Elmisaurus

Elmisaurus is an extinct genus of dinosaur from the Late Cretaceous. It was a theropod belonging to the Oviraptorosauria. Its fossils have been found in Mongolia. It is known from foot and hand bones.

Ganzhousaurus

Ganzhousaurus is an extinct genus of oviraptorine oviraptorid dinosaur known from the Late Cretaceous Nanxiong Formation of Nankang County, Ganzhou City of Jiangxi Province, southern China. It was found in a Maastrichtian deposit and contains a single species, Ganzhousaurus nankangensis. It is distinguished by a combination of primitive and derived features.

Iren Dabasu Formation

The Iren Dabasu Formation is a Mesozoic geologic formation in the Iren Nor region of Inner Mongolia. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation.

It is located in the Iren Nor region of China, and dates from the Upper Cretaceous.

It is typically referred to continental clastic sediments consisting of light grey fine sandstones, coarse sandstones and glutenites as well as mottled claystones and siltstones. This lithological unit has yielded plentiful dinosaur remains in quantity and group, also including a great deal of microfossil material. The stratigraphic sequence, sedimentary system, and the morphologies and assemblages of the paleontological taxa are summarized on the basis of previous studies on the Iren Dabasu Formation. The fine-grained floodplain sediments and the coarse-grained sediments of the point bar formed a series of repeated frequently binary sedimentary rhythms. The “binary structure” of the sedimentary rhythms strongly indicates meandering stream deposits rather than braided river deposits as previously thought. The ostracod and charophyte assemblages of the Iren Dabasu Formation has suggested a potential correlation with those of the Sifangtai Formation and the basal Mingshui Formation in the Songliao Basin (mid/late Campanian age). Vertebrates point to an older date than middle-late Campanian. The turtle Khunnuchelys is known from both Iren Dabasu and Baynshirenian-equivalent units such as the Bostobe and Bissekty. In addition, a giant Caenagnathid similar to Gigantoraptor is now known from the Baynshirenian beds of Tsagaan Teg. Like the coeval Baynshiree (or possibly Javkhlant) Formation in the Gobi, the dinosaur fauna of the Iren Dabasu Formation includes tyrannosaurs, ornithomimids, therizinosaurs and oviraptors. Gigantism, such in the case of Gigantoraptor, may have been due the humid climate of the Iren Nor region during the Late Cretaceous. It may also have been due to weak contemporary tyrannosaurs, as predator decline tends to maximize herbivore diversity.

Macroelongatoolithus

Macroelongatoolithus is an oogenus of large, fossil theropod eggs (probably representing a giant oviraptorid). They are known from Asia and from North America.

Nankangia

Nankangia is an extinct genus of caenagnathoid oviraptorosaurian dinosaur known from the Late Cretaceous Nanxiong Formation of Nankang County, Ganzhou City of Jiangxi Province, southeastern China. It contains a single species, Nankangia jiangxiensis. N. jiangxiensis coexisted with at least four other caenagnathoids, including an unnamed oviraptorid, Banji long, Ganzhousaurus nankangensis and Jiangxisaurus ganzhouensis. The relatively short dentary and non-downturned mandibular symphysis of Nankangia suggest that it may have been more herbivorous than carnivorous.

Oviraptorosauria

Oviraptorosaurs ("egg thief lizards") are a group of feathered maniraptoran dinosaurs from the Cretaceous Period of what are now Asia and North America. They are distinct for their characteristically short, beaked, parrot-like skulls, with or without bony crests atop the head. They ranged in size from Caudipteryx, which was the size of a turkey, to the 8-metre-long, 1.4-ton Gigantoraptor. The group (along with all maniraptoran dinosaurs) is close to the ancestry of birds. Analyses like those of Maryanska et al (2002) and Osmólska et al. (2004) suggest that they may represent primitive flightless birds. The most complete oviraptorosaur specimens have been found in Asia. The North American oviraptorosaur record is sparse.The earliest and most basal ("primitive") known oviraptorosaurs are Ningyuansaurus wangi, Protarchaeopteryx robusta and Incisivosaurus gauthieri, both from the lower Yixian Formation of China, dating to about 125 million years ago during the Aptian age of the early Cretaceous period. A tiny neck vertebra reported from the Wadhurst Clay Formation of England shares some features in common with oviraptorosaurs, and may represent an earlier occurrence of this group (at about 140 million years ago).

Planet Dinosaur

Planet Dinosaur, is a six-part documentary television series created by Nigel Paterson and Phil Dobree, produced by the BBC, and narrated by John Hurt. It first aired in the United Kingdom in 2011, with VFX studio Jellyfish Pictures as its producer. It is the first major dinosaur-related series for BBC One since Walking with Dinosaurs. There are more than 50 different prehistoric species featured, and they and their environments were created entirely as computer-generated images, for around a third of the production cost that was needed a decade earlier for Walking with Dinosaurs. Much of the series' plot is based on scientific discoveries made since Walking with Dinosaurs. The companion book to Planet Dinosaur was released on 8 September 2011, and the DVD and Blu-ray were released on 24 October 2011.

Santonian

The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series. It spans the time between 86.3 ± 0.7 mya (million years ago) and 83.6 ± 0.7 mya. The Santonian is preceded by the Coniacian and is followed by the Campanian.

Sonidosaurus

Sonidosaurus is a genus of sauropod dinosaur from the Late Cretaceous. It was a titanosaur which lived in what is now Inner Mongolia. The type species, Sonidosaurus saihangaobiensis, was described by Xu, Zhang, Tan, Zhao, and Tan in 2006. It was a small titanosaur, about 9 meters (30 ft) long. It was found in the Iren Dabasu Formation; it was only slightly larger than the contemporaneous giant oviraptorid Gigantoraptor.

Xu Xing (paleontologist)

Xu Xing (Chinese: 徐星; pinyin: Xú Xīng; born 1969) is a Chinese paleontologist who has named more dinosaurs than any other living paleontologist. Such dinosaurs include the Jurassic ceratopsian Yinlong, the Jurassic tyrannosauroid Guanlong, the large oviraptorosaur Gigantoraptor, and the troodontid Mei. He was born in Xinjiang, China, in 1969. A graduate from the department of geology of Peking University, he is currently a research fellow at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences in Beijing. He had originally planned to become a software designer. However, he was assigned to the department of geology as the university's department of physics did not have any admission quota in Xinjiang. He graduated in 1995, and claims inspiration from Roy Chapman Andrews.Among Xu's paleontological contributions have been discovery and analysis of dinosaur fossils with avian characteristics, and development of theories in regarding the evolution of feathers.

Yulong mini

Yulong is an extinct genus of derived oviraptorid theropod dinosaur known from the Late Cretaceous Qiupa Formation of Henan Province, central China. It contains a single species, Yulong mini. It is known from many juvenile specimens that represent some of the smallest known oviraptorids.

Basal oviraptorosaurs
Caudipteridae
Caenagnathoidea

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