Dzharaonyx

Discovery and naming

All remains of Dzharaonyx were found at a single locality, Dzharakuduk, in the Kyzylkum Desert of Uzbekistan. The first alvarezsaurid fossils later referred to this genus were discovered by Soviet paleontologist Lev Nesov between 1977 and 1994. Additional remains were recovered from 1997 to 2006 by the URBAC joint-paleontological expedition, a collaboration of Uzbekistan, Russia, Britain, America, and Canada. Alvarezsaur remains were exceedingly rare; as of a 2017 publication, only seven bones confidently attributable to alvarezsaurs had been found among over 3500 catalogued dinosaur fossils.

Despite being fragmentary, these bones were readily identifiable due to distinctive hand and tail anatomy. Although many specimens were described in 2017, the taxon was not fully named until 2022, when Alexander Averianov and Hans Dieter-Sues published on it. Additional specimens recovered in the intervening years were all referred to Dzharaonyx, as no evidence of more than one alvarezsaurid taxon existed at the locality.

Description

Dzharaonyx was a relatively small dinosaur, like all parvicursorines. The describing authors gave no precise size estimate, but subsequent researchers estimated it at around 50 cm long and about 1.75 kg, similar in size to Linhenykus. The holotype is a single right humerus (specimen ZIN PH 2619/16). All other alvarezsaurid specimens from Dzharakuduk were included in the hypodigm, comprising two series: ZIN PH 2440/16 to 2446/16 and ZIN PH 2616/16 to 2635/16.

Aside from the holotype humerus, elements represent all parts of the skeleton except the skull, including dorsal and caudal vertebrae, ulnae, carpometacarpi, hand phalanges, manual unguals, parts of the pubis, a metatarsal, foot phalanges, and a toe claw. Dzharaonyx is distinguished from other alvarezsaurids by autapomorphies such as opisthocoelous dorsal vertebrae lacking a fossa between the zygapophyses, procoelous caudal vertebrae with a canal inside the neural arch, a very large olecranon process of the ulna, and an arctometatarsus.

Classification

When Averianov and Sues described Dzharaonyx in 2022, their phylogenetic analysis recovered it within a monophyletic Parvicursorinae. Its membership in this clade was supported by large neural canals on dorsal vertebrae and extreme elongation of the posterior dorsal centra. Dzharaonyx represents the oldest record of Parvicursorinae anywhere, supporting an Asian origin for the group. Its humerus is superficially similar to that of Patagonykus, but Averianov and Sues considered this homoplastic and not reflective of a close relationship; the anatomy is very consistent with other Asian parvicursorines.

In 2024, a study led by Jorge Gustavo Meso, including Diego Pol and Peter Makovicky, reaffirmed these findings. Their phylogenetic analysis also placed Dzharaonyx within Parvicursorinae and suggested its appearance reflects a miniaturization event in alvarezsaurian evolution during the early-to-middle Cenomanian.

Paleoecology

No skull remains of Dzharaonyx are known, so direct observations about its feeding habits cannot be inferred. However, the diet of derived alvarezsauroids has been a topic of speculation. The major diversification of parvicursorines coincided with the Cretaceous Terrestrial Revolution, marked by the spread of angiosperms and the evolution of eusociality in Hymenoptera. These developments, along with the unique morphology of alvarezsaurid hands, suggest they may have specialized in feeding on colonial insects like ants.

The Bissekty Formation's lithology consists largely of cross-bedded sandstones with interbeds of massive sandstone, conglomerate, siltstones, and mudstones; most fossils are found as clasts within conglomerates. The formation contains a mix of marine, brackish, freshwater, and terrestrial fossils, indicating it formed during the regression of a saltwater sea. A braided river system later replaced the coastline, and the area eventually became completely underwater during the later Aitym Formation.

The Dzharakuduk locality has also yielded fossils of the tyrannosauroid Timurlengia, the ankylosaur Bissektipelta, the probable carcharodontosaurid Ulughbegsaurus, enantiornithines, and amphibians.