| Kiyacursor | |
|---|---|
 | |
| Holotype specimen | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Family: | †Noasauridae |
| Genus: | †Kiyacursor Averianov et al., 2024 |
| Species: | †K. longipes |
| Binomial name | |
| †Kiyacursor longipes Averianov et al.,2024 | |
Kiyacursor (meaning "Kiya River runner") is anextinct genus ofnoasauridtheropoddinosaur from theEarly CretaceousIlek Formation of Russia. The genus contains asingle 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, afterKileskus in 2010.
TheKiyacursorholotype specimen,KOKM 5542, was discovered in the summer of 2023 in sediments of theIlek Formation (Shestakovo 1 locality) by theKiya River inKemerovo Oblast, Russia.[1] The specimen consists of an incomplete skeleton, includingcervical andcaudal vertebrae, cervical and dorsalribs, a leftscapulocoracoid,humeri, and much of botharticulated hind limbs.[2]
A partial cervical vertebra,PIN 329/16, was first described in 2023 by Averianov & Lopatin as belonging to a long-necked theropod similar tobasaltherizinosauroids likeFalcarius.[3] Since this specimen was found in the same locality as theKiyacursor holotype, Averianov et al. (2024) suggested that the vertebra may represent the same individual as KOKM 5542.[2]
In early2024, the name "Kiyacursor" (alternatively spelled "Kyacursor") was first mentioned in online sources, including press and social media, but remained anomen nudum as the peer-reviewed description had not yet been published.[1]
Later that year, Averianov and colleagues formallydescribedKiyacursor longipes as a new genus and species of noasaurid theropod based on these fossil remains. Thegeneric name,Kiyacursor, combines a reference to the Kiya River near thetype locality with theLatin word "cursor", meaning "runner". Thespecific name,longipes, combines the Latin words "longus", meaning "long", and "pes", meaning "foot".[2]
Averianov et al. (2024) estimated the body length ofKiyacursor at 2.5 metres (8.2 ft). Based onpaleohistological 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.[2]
The thirdmetatarsal ofKiyacursor is large, and the second metatarsal is significantly reduced. A similar morphology is observed in the relatedElaphrosaurus andLimusaurus, as well as theextantostrich. This suggests thatKiyacursor likely possessed notablecursorial abilities, being capable of running at high speeds.[2]
In the strict consensus tree of theirphylogenetic analyses, Averianov et al. (2024) recoveredKiyacursor in aclade ofbasalnoasaurids along withAfromimus and an unnamed specimen from theEumeralla Formation of Australia,[4] which, in turn, is thesister taxon to the clade formed by theNoasaurinae andElaphrosaurinae. These results are displayed in thecladogram below:[2]
Kiyacursor was found in outcrops of theIlek Formation, which dates to theAptian age of the Early Cretaceous. Other non-avian dinosaurs named from the formation include the earlyceratopsianPsittacosaurus sibiricus and thesomphospondylan sauropodSibirotitan.[5][6] Remains of birds (Evgenavis andMystiornis)[7][8] and indeterminate dinosaurs (including theropods, sauropods, and stegosaurs) have also been discovered.[9] Fossilpterosaurs, crocodylomorphs, turtles, lizards, varioussynapsids (includingmammaliaforms), and amphibians are also known from the formation.[10] Many of these animals represent relict populations of groups otherwise known from the Jurassic, suggesting that this area of Siberia was arefugium for them.[2][11][12]
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