''Jaculinykus'' (meaning "

Jaculus The jaculus (or iaculus, pl. ''jaculi'', meaning "thrown" in Latin) is a small mythical serpent or dragon. It can be shown with wings and sometimes has front legs. It is also sometimes known as the javelin snake. In Greek mythology It was said ...

claw") is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus of

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 ...

theropod dinosaur from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

Baruungoyot Formation The Baruungoyot Formation (also known as Barun Goyot) is a geological formation dating to the Late Cretaceous Period. It is located within and is widely represented in the Gobi Desert Basin, in the Ömnögovi Province of Mongolia. Description ...

Mongolia Mongolia is a landlocked country in East Asia, bordered by Russia to the north and China to the south and southeast. It covers an area of , with a population of 3.5 million, making it the world's List of countries and dependencies by po ...

. The genus contains a single species, ''J. yaruui'', known from a nearly complete articulated skeleton including bones of the skull. ''Jaculinykus'' is notable for its unique hand, which has a hypertrophied first digit and greatly reduced second digit, which is intermediate between the tridactyl hand of ''

Shuvuuia ''Shuvuuia'' is a genus of bird-like theropod dinosaur from the late Cretaceous period of Mongolia. It is a member of the family Alvarezsauridae, small coelurosaurian dinosaurs which are characterized by short but powerful forelimbs specialized ...

'' and monodactyl hand of ''

Linhenykus ''Linhenykus'' is an extinct genus of alvarezsaurid theropod dinosaur from the Late Cretaceous of Inner Mongolia, China. It is the most basal known member of the Parvicursorinae. The genus gets its name from Linhe, a city near the site where t ...

''.

Discovery and naming

Mongolian alvarezsaurids stratigraphic occurrence

The ''Jaculinykus''

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

specimen, MPC-D 100/209, was discovered in sediments of the

(Nemegt locality), of

Ömnögovi Province Ömnögovi ( ''Ömnögovǐ'', ''South Gobi'') is an aimag (province) of Mongolia, located in the south of the country, in the Gobi Desert. Ömnögovi is Mongolia's largest aimag. The capital is Dalanzadgad. The province is rich in mineral dep ...

, Mongolia. The specimen consists of a nearly complete skeleton with most of the skull. In 2023, Kubo ''et al''. described ''Jaculinykus yaruui'' as a new genus and species of parvicursorine alvarezsaurid based on these fossil remains. The generic name, "''Jaculinykus''", combines a reference to the

, a small dragon in

Greek mythology Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of ancient Greek folklore, today absorbed alongside Roman mythology into the broader designation of classical mythology. These stories conc ...

with the

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

word "onykus," meaning "claw". The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

"''yaruui''" is derived from "yaruu" ("яаруу"), the Mongolian word for "speedy" or "hasty".

Classification

''Jaculinykus'' was added to a phylogenetic analysis and found to be in the clade

Parvicursorinae 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 a clade consisting of all alvarezsaurs from the Nemegt Basin. The cladogram from Kubo ''et al.'' (2023) is shown below:

Paleoecology

Fossils of ''

Ondogurvel ''Ondogurvel'' (meaning "egg lizard") is a genus of alvarezsaurid dinosaur from the Late Cretaceous (Campanian) Barun Goyot Formation in southern Mongolia. The type and only species is ''O. alifanovi'', known from a partial skeleton consisting of ...

'', another parvicursorine alvarezsaurid, as well as fossils of ''

Nemegtomaia ''Nemegtomaia'' is a genus of oviraptorid dinosaur from what is now Mongolia that lived in the Late Cretaceous Period (geology), Period, about 70million years ago. The first specimen was found in 1996, and became the basis of the new genus and s ...

'', an oviraptorosaur, are also known from the Nemegt locality of the Mongolian

Barun Goyot Formation The Baruungoyot Formation (also known as Barun Goyot) is a geological formation dating to the Late Cretaceous Period. It is located within and is widely represented in the Gobi Desert Basin, in the Ömnögovi Province of Mongolia. Descriptio ...

. Other localities from the formation have yielded dinosaurs including additional alvarezsaurids (''

Ceratonykus ''Ceratonykus'' (meaning "horned claw") is a monospecific genus of alvarezsaurid dinosaur from Mongolia that lived during the Late Cretaceous (late Campanian stage, 72.1 Ma) in what is now the Barun Goyot Formation. The type and only species, ''C ...

,'' '' Khulsanurus'', and ''

Parvicursor ''Parvicursor'' (meaning "small runner") is a genus of tiny maniraptoran dinosaur with long slender legs for fast running. Discovery and naming The holotype PIN no. 4487/25, mostly consisting of vertebrae, the pelvis and the right hindlimb, w ...

''), as well as dromaeosaurs ('' Hulsanpes'','''' '' Kuru'', and ''

Shri Shri (; , ) is a Sanskrit term denoting resplendence, wealth and prosperity, primarily used as an honorific. The word is widely used in South and Southeast Asian languages such as Assamese, Meitei ( Manipuri), Marathi, Malay (including In ...

''), oviraptorosaurs (''

Conchoraptor ''Conchoraptor'' (meaning "conch plunderer") is a genus of oviraptorid dinosaurs that lived in Asia during the Late Cretaceous epoch, about 70 million years ago. It is known from the Barun Goyot and Nemegt Formation, Nemegt formations of Mongolia ...

'' and ''

Heyuannia ''Heyuannia'' ("from Heyuan") is a genus of oviraptorid dinosaur that lived in Asia during the Late Cretaceous epoch, in what is now China and Mongolia. It was the first oviraptorid found in China; most others were found in neighbouring Mongolia ...

''), a sauropod (''

Quaesitosaurus ''Quaesitosaurus'' (meaning "extraordinary lizard") is a genus of nemegtosaurid sauropod containing only the type species, ''Q. orientalis'', described in 1983. It lived from 72 to 71 million years ago during the Late Cretaceous epoch in the Barun ...

''),'''' ceratopsians (''

Bagaceratops ''Bagaceratops'' (meaning "small-horned face") is a genus of small protoceratopsid dinosaurs that lived in Asia during the Late Cretaceous, around 72 to 71 million years ago. ''Bagaceratops'' remains have been reported from the Barun Goyot Forma ...

'' and ''

Breviceratops ''Breviceratops'' (meaning "short horned face") is a genus of protoceratopsid dinosaur that lived during the Late Cretaceous in what is now the Barun Goyot Formation, Mongolia. Discovery and naming The first fossils were discovered during the 1 ...

''), a pachycephalosaur ('' Tylocephale''), and ankylosaurs (''

Saichania ''Saichania'' (Mongolian meaning "beautiful one") is a genus of herbivorous ankylosaurid dinosaur from the Late Cretaceous period of Mongolia. The first fossils of ''Saichania'' were found in the early 1970s in Mongolia. In 1977 the type speci ...

'', ''

Tarchia ''Tarchia'' (meaning "brainy one") is a genus of herbivorous ankylosauridae, ankylosaurid dinosaur from the late Cretaceous of Mongolia. Discovery and naming In 1970, a Polish-Mongolian expedition discovered an ankylosaurian skull near Khulsan. ...

'', and ''

Zaraapelta ''Zaraapelta'' is an extinct genus of herbivorous ankylosaurid thyreophoran dinosaur from the Late Cretaceous of Mongolia. The type species is ''Zaraapelta nomadis'', named and described by Arbour ''et al'' in 2014. ''Zaraapelta'' is known from ...

'').

References

{{Taxonbar, from=Q123458061 Alvarezsauridae Dinosaur genera Maastrichtian dinosaurs Baruungoyot Formation Fossil taxa described in 2023 Dinosaurs of Mongolia