''Datanglong'' is an extinct

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 ...

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...

belonging to either

Carcharodontosauria Allosauroidea is a superfamily or clade of theropod dinosaurs which contains four families — the Metriacanthosauridae, Allosauridae, Carcharodontosauridae, and Neovenatoridae. Allosauroids, alongside the family Megalosauroidea, were among t ...

Megaraptora Megaraptora is a clade of carnivorous Tetanurae, tetanuran theropod dinosaurs with controversial relations to other theropods. Its Derived (phylogenetics), derived members, the Megaraptoridae are noted for their elongated hand claws and proporti ...

. It existed during the Early Cretaceous (

Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is precede ...

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/ Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± 0 ...

) in what is now southeastern China.

Discovery and naming

In 2011, staff of the Geological Survey Research Institute at the village of Nazao, twenty kilometers southwest of the town of Datang, near Nanning in Guangxi, discovered the remains of a large theropod new to science. The dinosaur was named and described in 2014 as ''Datanglong guangxiensis'', by Mo Jinyou, Zhou Fusheng, Li Guangning, Hunag Zhen and Cao Chenyun. The genus name combines a reference to the Datang basin with the Chinese word ''long'', "dragon". The specific name refers to the province of Guangxi. ''Datanglong guangxiensis'' is known from one specimen,

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

GMG 00001, which encompasses

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

e and hip bones. There is a series of vertebrae that begins with the last dorsal (back) vertebra (according to the descriptors the fourteenth), continues over the five sacral vertebrae, and ends with the second tail vertebra. The sacrum is attached to a left ilium with the upper parts of the left

pubic bone In vertebrates, the pubic region ( la, pubis) is the most forward-facing ( ventral and anterior) of the three main regions making up the coxal bone. The left and right pubic regions are each made up of three sections, a superior ramus, inferior ...

and the left ischium, and one piece of the right ilium. The bones were found in a layer of the Xinlong Formation, which was deposited sometime during the Early Cretaceous.

Description

''Datanglong'' is a large predatory theropod with a length of roughly . The specimen has a preserved length of about .

Distinguishing features

The describing authors determined some distinguishing characteristics. The last dorsal vertebra has a pleurocoel, or pneumatic cavity, that is bounded by an enlarged posterior ridge between the diapophysis and the vertebral body, by the posterior ridge between the parapophysis and the vertebral body; and by the vertebral body itself. The rear dorsal vertebra has a well-developed horizontal ridge between the

prezygapophysis The articular processes or zygapophyses (Greek ζυγον = "yoke" (because it links two vertebrae) + απο = "away" + φυσις = "process") of a vertebra are projections of the vertebra that serve the purpose of fitting with an adjacent vertebr ...

and the parapophysis. The last dorsal vertebra has a parapophysis that protrudes more laterally than the diapophysis. The groove in the underside of the rear blade of the ilium, serving as an attachment to the ''

musculus caudofemoralis brevis Musculus may refer to: * Andreas Musculus (1514–1581), German Lutheran theologian *Heinrich Musculus (b. 1868), Swedish-Norwegian businessperson *Wolfgang Musculus Wolfgang Musculus, born "Müslin" or "Mauslein", (10 September 1497 – 30 Augus ...

'', is shallow and the "brevis shelf", the inner surface of the medial blade wall uncovered by it, is short and shaped like a ridge. The pubic peduncle of the ilium, to which the pubic bone is attached, at the rear side transversely expands to below.

Skeleton

The last dorsal vertebra resembles those of the

Ceratosauria Ceratosaurs are members of the clade Ceratosauria, a group of dinosaurs defined as all theropods sharing a more recent common ancestor with ''Ceratosaurus'' than with birds. The oldest known ceratosaur, '' Saltriovenator'', dates to the earliest ...

in that the parapophysis, the lower rib joint process, extends beyond the diapophysis, the upper rib joint process. The vertebra is also clearly pneumatised but the succeeding sacral vertebrae of the sacrum are not. The first tail vertebra has a depression at the level of the probable ridge between the

and the parapophysis. This vertebra also has a straight

chevron Chevron (often relating to V-shaped patterns) may refer to: Science and technology * Chevron (aerospace), sawtooth patterns on some jet engines * Chevron (anatomy), a bone * '' Eulithis testata'', a moth * Chevron (geology), a fold in rock ...

. The

spinous process The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

es of the tail vertebrae are broken but the remaining pieces are fairly long and expand upwards. The upper profile of the ilium is unknown, due to damage. The front blade has a deeply drooping point with a rounded front edge. The vertical ridge in front of the hip joint does not form a medial shelf. The blade of the ilium is pierced by several pneumatic cavities. The pubic peduncle of the ilium is widely excavated at the rear and has a rectangular bottom surface, twice longer than wide. The ischial peduncle inserts into an upper cavity of the ischium like a pin.

Phylogeny

The describing authors placed ''Datanglong'' in the

, in a basal position, making use of a previous

cladistic Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived char ...

analysis of Matthew Carrano. Soon after the publication, the Italian paleontologist Andrea Cau pointed out that this analysis had been strongly focused on the basal Tetanurae and therefore contained few traits of the

Coelurosauria Coelurosauria (; from Greek, meaning "hollow tailed lizards") is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. Coelurosauria is a subgroup of theropod dinosaurs that includes compsognathids, t ...

. That carried the danger that basal coelurosaurians were misplaced. Cau entered the traits of ''Datanglong'' into his own, more comprehensive, analysis and this indeed revealed that ''Datanglong'' was a basal coelurosaur. If this is correct, it would be the first known basal coelurosaur of a truly large size. He also directed attention to the fact that all synapomorphies that ''Datanglong'' shared with the Carcharodontosauria (the pneumatized cavities in the ilium and the pin-and-socket connection between the ilium and the ischium) were also shared with the

. In 2017, Adun Samathi and Phorphen Chanthasit reported in an SVP abstract that they found ''Datanglong'' to nest in Megaraptora, "sharing the pneumaticity of the ilium with other megaraptorans."

References

{{Taxonbar, from=Q17984025 Early Cretaceous dinosaurs of Asia Prehistoric tetanurans Fossil taxa described in 2014 Paleontology in Guangxi