| Nqwebasaurus | |
|---|---|
 | |
| Life restoration | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Clade: | †Ornithomimosauria |
| Genus: | †Nqwebasaurus de Klerk et al., 2000 |
| Species: | †N. thwazi |
| Binomial name | |
| †Nqwebasaurus thwazi de Klerk et al., 2000 | |
Nqwebasaurus is a probableornithomimosauriantheropod from theEarly Cretaceous ofSouth Africa. The genus contains a single species,Nqwebasaurus thwazi, representing the oldest known coelurosaur inAfrica and the evidence for basal coelurosaurian dinosaurs inhabitingGondwana since the earliest Cretaceous period.[1]
Thetype specimen ofNqwebasaurus was discovered from theKirkwood Formation of theUitenhage Group by William J. de Klerk of theAlbany Museum and Callum Ross of theStony Brook University in July 1996 during a joint expedition. 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.[2][3] It has an unofficial nickname "Kirky", since it was found in the Kirkwood Formation.[4]
The nameNqwebasaurus is derived from theXhosa wordNqweba which is the local name for theKirkwood district, andthwazi is ancient Xhosa for "fast runner".[2][3]
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 thecaudal vertebrae of the type specimen being incomplete.[1][2] Gregory S. Paul estimated its adult size at 1 m (3.3 ft) in length and 1 kg (2.2 lb) in body mass.[5] In addition the type specimen is thought to be a latejuvenile, although with the type specimen being the onlyfossil 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 asStruthiomimus.[1]Nqwebasaurus also lacks serrations on its maxillary teeth, has a reduced dentition, and containsgastroliths 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.[2] Due to these morphological traits,Nqwebasaurus is thought to have been anomnivore.
As more basal theropod species, especially those on the evolutionary line to birds, had feathers it is accepted thatNqwebasaurus was likely at least partially feathered or had a feather coat forthermoregulation.
The most recentphylogenetic analyses that includeNqwebasaurus recovered it in the position as the basalmost member ofOrnithomimosauria.[1][6] However, many older studies have recovered different positions for the taxon amongst Coelurosauria, ranging from a basal member of the group, acompsognathid, or analvarezsaurid. In combination with the rather divergent anatomy ofNqwebasaurus in comparison to other ornithomimosaurs, it is potentially uncertain what the taxon's phylogenetic affinities may be.[7]
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 ofNqwebasaurus.[6]
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