''Kiyacursor'' (meaning "

Kiya River The Kiya () is a river in Tomsk and Kemerovo Oblasts of Russia. It is a left tributary of the Chulym (in the Ob's drainage basin), and is long, with a drainage basin of . The river has its sources in the Kuznetsk Alatau and flows in a northweste ...

runner") 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 noasaurid

theropod Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...

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

from the

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

Ilek Formation The Ilek Formation is a Lower Cretaceous geologic Formation (geology), formation in Western Siberia. Many different fossils have been recovered from the formation. It overlies the Late Jurassic Tyazhin Formation and underlies the Albian Kiya Form ...

of Russia. The genus contains a single species, ''K. longipes'', known from a partial skeleton. ''Kiyacursor'' represents the first Early Cretaceous ceratosaur discovered in Asia, as well as the second non-avian theropod named from Russia, after ''

Kileskus ''Kileskus'' (meaning ''lizard'' in the Khakas language) is a genus of tyrannosauroid dinosaur known from partial remains found in Middle Jurassic (Bathonian stage) Itat Formation of Sharypovsky District, Krasnoyarsk Krai (Russia). Fossils r ...

'' in 2010.

Discovery and naming

The ''Kiyacursor''

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, KOKM 5542, was discovered in the summer of 2023 in sediments of the

(Shestakovo 1 locality) by the

Kemerovo Oblast Kemerovo Oblast (, ), also known as Kuzbass (, ), after the Kuznetsk Basin, is a federal subjects of Russia, federal subject of Russia (an oblast). Kemerovo is the administrative center and largest city of the oblast. Kemerovo Oblast is one of Rus ...

, Russia. The specimen consists of an incomplete skeleton, including cervical and

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 ...

, cervical and dorsal

rib In vertebrate anatomy, ribs () are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the thoracic cavity, enabling the lungs to expand and thus facilitate breathing by expanding the ...

s, a left

scapulocoracoid The scapulocoracoid is the unit of the pectoral girdle that contains the coracoid and scapula. The coracoid itself is a beak-shaped bone that is commonly found in most vertebrates with a few exceptions. The scapula is commonly known as the ''shoulde ...

humeri The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of ...

, and much of both

articulated An articulated vehicle is a vehicle which has a permanent or semi-permanent coupling in its construction. This coupling works as a large pivot joint, allowing it to bend and turn more sharply. There are many kinds, from heavy equipment to buse ...

hind limbs. A partial cervical vertebra,

PIN A pin is a device, typically pointed, used for fastening objects or fabrics together. Pins can have the following sorts of body: *a shaft of a rigid inflexible material meant to be inserted in a slot, groove, or hole (as with pivots, hinges, an ...

329/16, was first described in 2023 by Averianov & Lopatin as belonging to a long-necked theropod similar to basal therizinosauroids like ''

Falcarius ''Falcarius'' (meaning "sickle cutter") is a genus of primitive therizinosaur dinosaur that lived during the Early Cretaceous period in what is now North America. Its remains were first collected in the Cedar Mountain Formation in 1999, with subs ...

''. Since this specimen was found in the same locality as the ''Kiyacursor'' holotype, Averianov et al. (2024) suggested that the vertebra may represent the same individual as KOKM 5542. In early

2024 The year saw the list of ongoing armed conflicts, continuation of major armed conflicts, including the Russian invasion of Ukraine, the Myanmar civil war (2021–present), Myanmar civil war, the Sudanese civil war (2023–present), Sudane ...

, the name "Kiyacursor" (alternatively spelled "Kyacursor") was first mentioned in online sources, including press and social media, but remained a ''

nomen nudum In Taxonomy (biology), taxonomy, a ''nomen nudum'' ('naked name'; plural ''nomina nuda'') is a designation which looks exactly like a scientific name of an organism, and may have originally been intended to be one, but it has not been published ...

'' as the peer-reviewed description had not yet been published. Later that year, Averianov and colleagues formally described ''Kiyacursor longipes'' as a new genus and species of noasaurid theropod based on these fossil remains. The generic name, ''Kiyacursor'', combines a reference to the Kiya River near the type locality with the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

word "cursor", meaning "runner". 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 ...

, ''longipes'', combines the Latin words "longus", meaning "long", and "pes", meaning "foot".

Description

Averianov et al. (2024) estimated the body length of ''Kiyacursor'' at . Based on paleohistological studies, they suggested that the holotype individual was an immature subadult when it died, having lived for three years or more. As such, it would have been larger as an adult. The third

metatarsal The metatarsal bones or metatarsus (: metatarsi) are a group of five long bones in the midfoot, located between the tarsal bones (which form the heel and the ankle) and the phalanges ( toes). Lacking individual names, the metatarsal bones are ...

of ''Kiyacursor'' is large, and the second metatarsal is significantly reduced. A similar morphology is observed in the related ''

Elaphrosaurus ''Elaphrosaurus'' ( ) is a genus of ceratosaurian Theropoda, theropod dinosaur that lived approximately 154 to 150 million years ago during the Late Jurassic, Late Jurassic Period in what is now Tanzania in Africa. ''Elaphrosaurus'' was a medium- ...

'' and ''

Limusaurus ''Limusaurus'' is a genus of theropod dinosaur that lived in what is now China during the Late Jurassic, around 161 to 157 million years ago. The type and only species ''Limusaurus inextricabilis'' was described in 2009 from specimens ...

'', as well as the

extant Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Exta ...

ostrich Ostriches are large flightless birds. Two living species are recognised, the common ostrich, native to large parts of sub-Saharan Africa, and the Somali ostrich, native to the Horn of Africa. They are the heaviest and largest living birds, w ...

. This suggests that ''Kiyacursor'' likely possessed notable

cursorial A cursorial organism is one that is adapted specifically to run. An animal can be considered cursorial if it has the ability to run fast (e.g. cheetah) or if it can keep a constant speed for a long distance (high endurance). "Cursorial" is often ...

abilities, being capable of running at high speeds.

Classification

In the strict consensus tree of their

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

, Averianov et al. (2024) recovered ''Kiyacursor'' in a

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 ...

of basal

noasaurids Noasauridae is an extinct family of theropod dinosaurs belonging to the group Ceratosauria. They were closely related to the short-armed abelisaurids, although most noasaurids had much more traditional body types generally similar to other ther ...

along with ''

Afromimus ''Afromimus'' (meaning "Africa mimic") is a genus of ceratosaurian theropod dinosaur from the Early Cretaceous Elrhaz Formation of Niger. It contains a single species, ''A. tenerensis'', named in 2017 by Paul Sereno from parts of the right leg, ...

'' and an unnamed specimen from the

Eumeralla Formation The Eumeralla Formation is a geological formation in Victoria, Australia whose strata date back to the Early Cretaceous. It is Aptian to Albian in age. Dinosaur remains are among the fossils that have been recovered from the formation, particul ...

of Australia, which, in turn, is the

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to the clade formed by the

Noasaurinae Noasauridae is an extinct family of theropod dinosaurs belonging to the group Ceratosauria. They were closely related to the short-armed abelisaurids, although most noasaurids had much more traditional body types generally similar to other ther ...

and Elaphrosaurinae. These results are displayed in the

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

below:

Paleoecology

''Kiyacursor'' was found in outcrops of the

, which dates to the

Aptian The Aptian is an age (geology), age in the geologic timescale or a stage (stratigraphy), stage in the stratigraphic column. It is a subdivision of the Early Cretaceous, Early or Lower Cretaceous epoch (geology), Epoch or series (stratigraphy), S ...

age of the Early Cretaceous. Other non-avian dinosaurs named from the formation include the early

ceratopsian Ceratopsia or Ceratopia ( or ; Greek: "horned faces") is a group of herbivorous, beaked dinosaurs that thrived in what are now North America, Asia and Europe, during the Cretaceous Period, although ancestral forms lived earlier, in the Late Ju ...

'' Psittacosaurus sibiricus'' and the

somphospondylan Somphospondyli is an extinct clade of titanosauriform sauropods that lived from the Late Jurassic until the end of the Late Cretaceous, comprising all titanosauriforms more closely related to Titanosauria proper than Brachiosauridae. The remain ...

sauropod ''

Sibirotitan ''Sibirotitan'' ("Siberian titan") is a genus of somphospondyl sauropod from the Ilek Formation of Russia. The type and only species is ''S. astrosacralis''. Discovery and naming The material assigned to ''Sibirotitan'' was found in the Shest ...

''. Remains of birds ('' Evgenavis'' and '' Mystiornis'') and indeterminate dinosaurs (including theropods, sauropods, and stegosaurs) have also been discovered. Fossil

pterosaurs Pterosaurs are an extinct clade of flying reptiles in the Order (biology), order Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 million to 66 million years ago). Pterosau ...

, crocodylomorphs, turtles, lizards, various

synapsids Synapsida is a diverse group of tetrapod vertebrates that includes all mammals and their extinct relatives. It is one of the two major clades of the group Amniota, the other being the more diverse group Sauropsida (which includes all extant rept ...

(including

mammaliaforms Mammaliaformes ("mammalian forms") is a clade of synapsid tetrapods that includes the crown group mammals and their closest extinct relatives; the group radiated from earlier probainognathian cynodonts during the Late Triassic. It is defined as ...

), and amphibians are also known from the formation. Many of these animals represent relict populations of groups otherwise known from the Jurassic, suggesting that this area of Siberia was a refugium for them.

References

{{Taxonbar, from=Q125911674 Noasauridae Dinosaur genera Aptian dinosaurs Fossil taxa described in 2024 Dinosaurs of Russia