''Nqwebasaurus'' is a basal coelurosaur and the basal-most member of the coelurosaurian

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

Ornithomimosauria from the Early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

. 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. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

and shows that basal coelurosaurian dinosaurs inhabited

Gondwana Gondwana ( ; ) was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia (continent), Australia, Zea ...

50 million years earlier than previously thought. The

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

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

Grahamstown Makhanda, formerly known as Grahamstown, is a town of about 75,000 people in the Eastern Cape province of South Africa. It is situated about northeast of Gqeberha and southwest of East London. It is the largest town in the Makana Local Mun ...

. 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 coelurosaur. 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 Caudal vertebrae are the vertebrae of the tail in many vertebrates. In birds, the last few caudal vertebrae fuse into the pygostyle, and in apes, including humans, the caudal vertebrae are fused into the coccyx. In many reptiles, some of the caud ...

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, 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 preserve ...

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

gastrolith A gastrolith, also called a stomach stone or gizzard stone, is a rock held inside a gastrointestinal tract. Gastroliths in some species are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. In ...

s 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 an

omnivore An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize t ...

. 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

The most recent

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

analyses that include ''Nqwebasaurus'' recovered it in the position as the basalmost member of Ornithomimosauria. However, many older studies have recovered different positions for the taxon amongst Coelurosauria, ranging from a basal member of the group, a compsognathid, or an

alvarezsaurid Alvarezsauridae is a family of small, long-legged dinosaurs. Although originally thought to represent the earliest known flightless birds, they are now thought to be an early diverging branch of maniraptoran theropods. Alvarezsaurids were highly ...

. In combination with the rather divergent anatomy of ''Nqwebasaurus'' in comparison to other ornithomimosaurs, it is potentially uncertain what the taxon's phylogenetic affinities may be. 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, South Africa Ornithomimosauria Dinosaur genera Valanginian dinosaurs Taxa named by Catherine Forster Taxa named by Scott D. Sampson Fossil taxa described in 2000 Dinosaurs of South Africa

History of discovery

Description

Classification

See also

References