''Nqwebasaurus'' (; anglicized as or ) is a basal

coelurosaur 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, tyrann ...

and is the basal-most member of the coelurosaurian

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

Ornithomimosauria Ornithomimosauria ("bird-mimic lizards") are theropod dinosaurs which bore a superficial resemblance to the modern-day ostrich. They were fast, omnivorous or herbivorous dinosaurs from the Cretaceous Period (geology), Period of Laurasia (now Asia ...

from the Early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

. 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 Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

and shows that basal coelurosaurian dinosaurs inhabited

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...

50 million years earlier than previously thought. The

type specimen In biology, a type is a particular wiktionary:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to a ...

of ''Nqwebasaurus'' was discovered by William J. de Klerk who is affiliated with the Albany Museum in

Grahamstown Makhanda, also known as Grahamstown, is a town of about 140,000 people in the Eastern Cape province of South Africa. It is situated about northeast of Port Elizabeth and southwest of East London, Eastern Cape, East London. Makhanda is the lar ...

. 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.

History of discovery

''Nqwebasaurus'' was first discovered by William J. de Klerk and Callum Ross in July 1996 during a joint expedition led by the Albany Museum in

and Stony Brook in New York, United States, where Callum Ross was affiliated at the time. The fossil is remarkably complete and is considered an extremely rare find as no coelurosaur fossils had previously been found in Africa at this time. No new ''Nqwebasaurus'' fossils have been discovered since.

Description

''Nqwebasaurus'' is considered to have been a small to medium-sized ornithomimosaur. The type specimen is approximately 30 cm (1 ft) high and is estimated to have been 90 cm (3 ft) long, although its complete length is not known due to the

caudal vertebrae 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 ...

of the type specimen being incomplete. Gregory S. Paul estimated its adult size at in length and in body mass. In addition the type specimen is thought to be a late

juvenile Juvenile may refer to: *Juvenile status, or minor (law), prior to adulthood *Juvenile (organism) *Juvenile (rapper) (born 1975), American rapper * ''Juvenile'' (2000 film), Japanese film * ''Juvenile'' (2017 film) *Juvenile (greyhounds), a greyho ...

, although with the type specimen being the only

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

representing its species it is currently not possible to compare the fossil with another member of its species. ''Nqwebasaurus'' has a long, three-fingered hand which includes a partially opposable thumb with a recurved claw. The claws on its hands differ in shape where the claws of the first and second digits are recurved and the third claw is not. This trait is unusual in theropod dinosaurs, however, it has been observed in some ornithomimosaurs such as '' Struthiomimus''. ''Nqwebasaurus'' also lacks serrations on its maxillary teeth, has a reduced dentition, and contains gastroliths in its abdominal cavity. Again this is unusual trait for carnivorous theropod dinosaurs as gastroliths are more commonly found in herbivorous vertebrates and modern ostriches. Due to these morphological traits, ''Nqwebasaurus'' is thought to have been a

herbivore A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...

. As more basal theropod species, especially those on the evolutionary line to birds, had feathers it is accepted that ''Nqwebasaurus'' was likely at least partially feathered or had a feather coat for

thermoregulation Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...

Classification

More recent

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analyses that include ''Nqwebasaurus'' support its current position as the basalmost member of

, one of the most basal

s of Coelurosauria, and the sister taxon of

Maniraptora Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the non-avian dinosaurs that were more closely related to them than to ''Ornithomimus velox''. It contains the major subgroups Avialae, Deinonychosauria, Oviraptoros ...

. However, new fossil material of coelurosaurs from the Early Cretaceous of Gondwana is much needed in order to gain a further understanding of Gondwanan coelurosaur

phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...

. The cladogram below follows an analysis by Yuong-Nam Lee, Rinchen Barsbold, Philip J. Currie, Yoshitsugu Kobayashi, Hang-Jae Lee, Pascal Godefroit, François Escuillié & Tsogtbaatar Chinzorig. The analysis was published in 2014, and displays the current phylogenetic position of ''Nqwebasaurus''.

References

{{Portalbar, Dinosaurs, Cretaceous, South Africa Ornithomimosaurs Early Cretaceous dinosaurs of Africa Cretaceous South Africa Fossils of South Africa Fossil taxa described in 2000 Taxa named by Catherine Forster Taxa named by Scott D. Sampson Xhosa language

History of discovery

Description

Classification

See also

References