| Udelartitan | |
|---|---|
 | |
| Hypotheticallife restoration | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Clade: | †Macronaria |
| Clade: | †Titanosauria |
| Superfamily: | †Saltasauroidea |
| Family: | †incertae sedis |
| Genus: | †Udelartitan |
| Species: | †U. celeste |
| Binomial name | |
| †Udelartitan celeste Soto et al.,2024 | |
Udelartitan is anextinct genus ofsaltasauroid titanosaurian sauropod dinosaur from theLate CretaceousGuichón Formation of Uruguay. The genus contains asingle species,U. celeste, known from fragmentary remains of at least two individuals.
TheUdelartitan fossil material was discovered in 2006 within sediments of theGuichón Formation (Araújo locality), nearQuebracho inPaysandú Department, Uruguay. Theholotype specimen, FC-DPV 3595, consists of the first threecaudal vertebrae in approximatearticulation. Additional bones representing an older individual (specimen FC-DPV 1900), including sixty caudal vertebrae, an incomplete left coracoid, theproximal and distal ends of thetibiae the proximal end of thefibula, sixmetatarsals, and twoastragali, were also referred toUdelartitan.[1] Many of the bones of the referred specimen were preliminarily described by Soto, Perea & Cambiaso in 2012, who also identified several purportedosteoderms.[2] However, Soto et al. (2024) found no evidence to support this assessment, arguing that they can more confidently be described asconcretions.[1]
In 2024, Soto et al.describedUdelartitan celeste as a new genus and species of titanosaur sauropod based on these fossil remains. Thegeneric name,Udelartitan, combines "UdelaR", an acronym for theUniversidad de la República (whose collection of vertebrae fossils includes those assigned toUdelartitan), with the word "titan", a common suffix for giant sauropod names, referencing thepre-Olympian gods ofGreek mythology. Thespecific name,celeste, is aSpanish word forsky blue, referencing the nickname given to someUruguayan athletic teams.[1]
Based on other titanosaurs known from more complete skeletons, Soto et al. (2024) suggest thatUdelartitan was about 15–16 metres (49–52 ft) in body length.[1]
In their preliminary description of some of theUdelartitan fossil material in 2012, Soto, Perea & Cambiaso used the general morphology of the caudal vertebrae and astragalus to suggest that it likely belonged to aderivedlithostrotian titanosaur—likely a non-saltasaurinesaltasaurid—related toPellegrinisaurus,Baurutitan, andAlamosaurus. They further cautioned that the Saltasauridae clade has historically had a very variable composition, comprising either very few or many species, depending on the analyses performed.[2]
In 2024, Soto et al. usedphylogenetic analyses to find the most likely position forUdelartitan within the Titanosauria. Similar to the previous work, they found support for a position within theSaltasauroidea. They used two data-matrices to assess the phylogenetic position ofUdelartitan, and recovered it either as a non-saltasaurid saltasauroid or abasal saltasaurine. Their results are displayed in thecladograms below:[1]
| Topology 1: Cerda et al. (2021) dataset[3] | Topology 2: Navarro et al. (2022) dataset[4]
|
Udelartitan is known from the Late CretaceousGuichón Formation of Uruguay. The exact age of this formation is uncertain. Some authors have historically suggested a Lower Cretaceous (Aptian–Albian) age due to similarities with theMigues Formation.[5] However, the overlyingMercedes Formation dates to theCampanian–Maastrichtian ages of theUpper Cretaceous, so this would introduce a significant gap in time. The discovery of dinosaur eggshells in the formation similar toSphaerovum prompted later researchers to favor a Late Cretaceous age for the Guichón Formation.[2]
Other fossils from the Guichón Formation include several specimens ofUruguaysuchus—acrocodyliform closely related toAraripesuchus—as well as the teeth of indeterminateiguanodontians andtheropods.[6][2] The youngerAsencio Formation of Uruguay also contains titanosaur specimens, including the centrum of a caudal vertebra referred toAeolosaurus sp.[1]
