''Patagonykus'' (meaning "Patagonian claw") is a genus of

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally ca ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is ...

from the Upper Cretaceous of

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

. This alvarezsauroid was discovered in exposures of the

Portezuelo Formation The Portezuelo Formation is a geologic formation of Late Cretaceous ( Late Turonian to Early Coniacian) age, outcropping in the Mendoza, Río Negro and Neuquén provinces of Argentina.Turonian The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous Epoch, or a stage in the Upper Cretaceous Series. It spans the time between 93.9 ± 0.8 Ma and 89.8 ± 1 Ma (million years ago). The Turonian is preceded by ...

Coniacian The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by t ...

) of the Rio Neuquén Subgroup in the

Neuquén Basin Neuquén Basin ( es, Cuenca Neuquina) is a sedimentary basin covering most of Neuquén Province in Argentina. The basin originated in the Jurassic and developed through alternating continental and marine conditions well into the Tertiary. The bas ...

, Neuquen Province of

Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and ...

. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

consists of an incomplete but well-preserved

skeleton A skeleton is the structural frame that supports the body of an animal. There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside ...

, lacking a

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

, but including many

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 i ...

, the

coracoid A coracoid (from Greek κόραξ, ''koraks'', raven) is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals). In therian mammals (including humans), a coracoid process is prese ...

s, a partial forelimb, pelvic girdle, and hindlimbs. ''Patagonykus'' has been classed with the

Alvarezsauridae 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 ...

, a family which includes such

taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

as the

Mongolia Mongolia; Mongolian script: , , ; literal translation, lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia Mongolia–Russia border, to the north and China China–Mongolia border, to the s ...

n '' Mononykus'' and the Argentinian ''

Alvarezsaurus ''Alvarezsaurus'' (; "Alvarez's lizard") is a genus of alvarezsaurid dinosaur from the Late Cretaceous, living in Argentina approximately 86 - 83 million years ago. It was a small dinosaur, measuring long and weighing approximately . It was fou ...

''. In 2010

Gregory S. Paul Gregory Scott Paul (born December 24, 1954) is an American freelance researcher, author and illustrator who works in paleontology, and more recently has examined sociology and theology. He is best known for his work and research on theropod dino ...

estimated its length at 1 meter (3.3 ft) and its weight at 3.5 kg (7.7 lbs).

Classification

Agnolin ''et al.'' (2012) originally placed ''Patagonykus'' within

, within the clade Patagonykinae as sister taxon to '' Bonapartenykus''. Makovicky, Apesteguía and Gianechini (2012) found it to be in a

polytomy An internal node of a phylogenetic tree is described as a polytomy or multifurcation if (i) it is in a rooted tree and is linked to three or more child subtrees or (ii) it is in an unrooted tree and is attached to four or more branches. A tr ...

with '' Alnashetri'', ''Bonapartenykus'', and a clade containing more deeply nested taxa such as ''

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 wher ...

'', '' Mononykus'' and ''

Albinykus ''Albinykus'' (meaning " Albin claw", after a term used by Mongolian shamans to describe light phenomena in the Gobi Desert) is a genus of alvarezsaurid dinosaur. Fossils have been found from Late Cretaceous-age (Santonian) Javkhlant Formation i ...

''. However, Xu ''et al.'' (2018) positioned it as a basal

Alvarezsauroidea Alvarezsauroidea is a group of small maniraptoran dinosaurs. Alvarezsauroidea, Alvarezsauridae, and Alvarezsauria are named for the historian Gregorio Álvarez, not the more familiar physicist Luis Alvarez, or his son geologist Walter Alvarez w ...

, sister taxon to ''Patagonykus'' and ''

Achillesaurus ''Achillesaurus'' is a genus of alvarezsaurid theropod dinosaur from the Santonian-age Upper Cretaceous Bajo de la Carpa Formation of Rio Negro, Argentina. It was named in reference to Achilles' heel, because diagnostic features are found ther ...

'', which was also recovered by Fowler ''et al.'' (2020). ''Patagonykus'' has also been recovered as sister taxon to ''Bonapartenykus'' and Alvarezsauridae by Qin ''et al.'' (2019), and sister taxon to only ''Patagonykus'' outside of Alvarezsauridae by Averianov & Lopatin (2022a) and Averianov & Lopatin (2022b). A phylogenetic analysis conducted by Fowler ''et al.'' (2020) is reproduced below. The results of an earlier analysis by Agnolin ''et al.'' (2012) are reproduced below.

Classification

References

Further reading