Chucarosaurus
{{Short description|Genus of titanosaurian dinosaurs}}
{{Speciesbox
| fossil_range = Late Cretaceous, {{fossilrange|Cenomanian|Turonian}}
| image = Chucarosaurus Skeletal.svg
| image_caption = Skeletal diagram of Chucarosaurus
| parent_authority = Agnolin et al., 2023
| display_parents = 2
| genus = Chucarosaurus
| species = diripienda
| authority = Agnolin et al., 2023
}}
Chucarosaurus (meaning "indomitable reptile") is an extinct genus of titanosaurian dinosaur from the Late Cretaceous (middle Cenomanian–lower Turonian) Huincul Formation of Argentina. The genus contains a single species, C. diripienda, known from various limb and pelvic bones.{{Cite journal |last1=Agnolin |first1=Federico L. |last2=Gonzalez Riga |first2=Bernardo J. |last3=Aranciaga Rolando |first3=Alexis M. |last4=Rozadilla |first4=Sebastián |last5=Motta |first5=Matías J. |last6=Chimento |first6=Nicolás R. |last7=Novas |first7=Fernando E. |date=2023-02-02 |title=A new giant titanosaur (Dinosauria, Sauropoda) from the Upper Cretaceous of Northwestern Patagonia, Argentina |url=https://www.sciencedirect.com/science/article/pii/S0195667123000150 |journal=Cretaceous Research |volume=146 |language=en |pages=105487 |doi=10.1016/j.cretres.2023.105487 |bibcode=2023CrRes.14605487A |issn=0195-6671|url-access=subscription }}
Discovery and naming
The Chucarosaurus holotype specimen, MPCA PV 820, was discovered in sediments of the Huincul Formation, dated to the middle Cenomanian–lower Turonian ages of the late Cretaceous period, at Pueblo Blanco Natural Reserve in Río Negro Province, Argentina. The specimen consists of a complete left humerus, partial left radius, complete left metacarpal II, left ischium, partial left femur and fibula, partial right tibia, and partial indeterminate metapodial, all of which belong to one individual. An additional specimen (MPCA PV 821), consisting of a left femur and tibia, was assigned as the paratype.
In 2023, Agnolin et al. described Chucarosaurus diripienda, a new genus and species of colossosaurian titanosaurs, based on these fossil remains. The generic name, "Chucarosaurus", combines "chucaro", a Quechua word meaning "hard and indomitable animal" with the Latin word "saurus", meaning "reptile". The specific name, "diripienda", is derived from a Latin word meaning "scrambled".
Description
Chucarosaurus was a large, slender-limbed titanosaur. Its femur was roughly {{convert|1.9|m|ft}} long, somewhat smaller than the estimated {{convert|2.5|m|ft}} length of the femur of Argentinosaurus. The forelimb was shorter than the hindlimb, with a humerus 78% the length of the femur, as is typical of titanosaurs but unlike some basal titanosauriforms such as brachiosaurids. As in other colossosaurs, the deltopectoral crest of the humerus was thickened in its distal half. The ischium has a shorter, more robust iliac peduncle than in other titanosaurs.
Classification
File:Chucarosaurus Size Comparison.svg
Agnolin et al. (2023) recovered Chucarosaurus as a colossosaurian member of the Titanosauria, as the sister taxon to a clade formed by Notocolossus and the Lognkosauria. The results of their phylogenetic analyses are shown in the cladogram below:
{{clade
|{{clade
|1=Rinconsauria
|2={{clade
|1=Bonitasaura
|2={{clade
|1=Chucarosaurus
|2={{clade
|1=Notocolossus
|label2=Lognkosauria
|2={{clade
|2={{clade
|1={{clade
|1=Quetecsaurus
|2=Futalognkosaurus }}
|3={{clade
|1=Puertasaurus
|2=Drusilasaura
|3={{clade
|2=Patagotitan
}} }} }} }} }} }} }} }}|label1=Colossosauria}}
Palaeoenvironment
File:Huincul Formation Dinosauria Scale.svg compared to a human]]
Chucarosaurus is known from the Late Cretaceous Huincul Formation of Río Negro Province, Argentina. Many dinosaurs, including fellow titanosaurs (Argentinosaurus Bustingorrytitan, and Choconsaurus),{{Cite journal |last1=Simón |first1=M. E. |last2=Salgado |first2=L. |year=2023 |title=A new gigantic titanosaurian sauropod from the early Late Cretaceous of Patagonia (Neuquén Province, Argentina) |journal=Acta Palaeontologica Polonica|doi=10.4202/app.01086.2023 |doi-access=free }} rebbachisaurids (Cathartesaura, Cienciargentina, Limaysaurus, and Sidersaura),{{cite journal |last1=Calvo |first1=Jorge O. |last2=Salgado |first2=Leonardo |title=Rebbachisaurus tessonei sp. nov. a new Sauropoda from the Albian-Cenomanian of Argentina; new evidence on the origin of the Diplodocidae |journal=Gaia |volume=11 |date=1995 |pages=13–33 |url=https://www.dinochecker.com/papers/Calvo%2BSalgado-%5B1995%5D-Rebbachisaurus-tessonei.pdf |archive-url=https://web.archive.org/web/20210923134140/http://www.dinochecker.com/papers/Calvo+Salgado-%5B1995%5D-Rebbachisaurus-tessonei.pdf |archive-date=23 September 2021 }}{{Cite journal |last1=Simón |first1=M. E. |last2=Salgado |first2=L. |year=2025 |title=New rebbachisaurid (Dinosauria, Sauropoda) from the Huincul Formation (upper Cenomanian-Turonian) of Villa El Chocón (Neuquén Province, Argentina) |journal=Cretaceous Research |volume=173 |at=106137 |doi=10.1016/j.cretres.2025.106137 |bibcode=2025CrRes.17306137S }} carcharodontosaurids (Mapusaurus, Meraxes, and Taurovenator),{{cite journal |last1=Canale |first1=Juan I. |last2=Apesteguía |first2=Sebastián |last3=Gallina |first3=Pablo A. |last4=Mitchell |first4=Jonathan |last5=Smith |first5=Nathan D. |last6=Cullen |first6=Thomas M. |last7=Shinya |first7=Akiko |last8=Haluza |first8=Alejandro |last9=Gianechini |first9=Federico A. |last10=Makovicky |first10=Peter J. |title=New giant carnivorous dinosaur reveals convergent evolutionary trends in theropod arm reduction |journal=Current Biology |date=July 2022 |volume=32 |issue=14 |pages=3195–3202.e5 |doi=10.1016/j.cub.2022.05.057 |pmid=35803271 |s2cid=250343124 |doi-access=free |bibcode=2022CBio...32E3195C }} a megaraptoran (Aoniraptor), abelisaurids (Skorpiovenator, Tralkasaurus, and Ilokelesia), an elaphrosaurine (Huinculsaurus),{{cite journal |last1=Baiano |first1=Mattia A. |last2=Coria |first2=Rodolfo A. |last3=Cau |first3=Andrea |title=A new abelisauroid (Dinosauria: Theropoda) from the Huincul Formation (lower Upper Cretaceous, Neuquén Basin) of Patagonia, Argentina |journal=Cretaceous Research |date=June 2020 |volume=110 |pages=104408 |doi=10.1016/j.cretres.2020.104408 |bibcode=2020CrRes.11004408B |s2cid=214118853 }} a paravian (Overoraptor), and the unusual avetheropod Gualicho have also been named from the formation.{{cite journal |last1=Cerroni |first1=M.A. |last2=Motta |first2=M.J. |last3=Agnolín |first3=F.L. |last4=Aranciaga Rolando |first4=A.M. |last5=Brissón Egli |first5=F. |last6=Novas |first6=F.E. |year=2020 |title=A new abelisaurid from the Huincul Formation (Cenomanian-Turonian; Upper Cretaceous) of Río Negro province, Argentina |journal=Journal of South American Earth Sciences |volume=98 |page=102445 |doi=10.1016/j.jsames.2019.102445 |bibcode=2020JSAES..9802445C |s2cid=213781725}}{{cite journal |author1=Matías J. Motta |author2=Federico L. Agnolín |author3=Federico Brissón Egli |author4=Fernando E. Novas |year=2020 |title=New theropod dinosaur from the Upper Cretaceous of Patagonia sheds light on the paravian radiation in Gondwana |journal=The Science of Nature |volume=107 |issue=3 |pages=Article number 24 |bibcode=2020SciNa.107...24M |doi=10.1007/s00114-020-01682-1 |pmid=32468191 |hdl=11336/135530 |s2cid=218913199|hdl-access=free }} Remains of unenlagiids, iguanodonts, and elasmarian ornithopods are also known.
References
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