Sidersaura (meaning "star lizard") is an extinct genus of rebbachisaurid sauropod dinosaur from the Late Cretaceous Huincul Formation of Argentina. The genus contains a single species, S. marae, known from the remains of four individuals. Sidersaura represents one of the largest known rebbachisaurids.
| Sidersaura Temporal range: Late Cretaceous,
| |
|---|---|
| |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Superfamily: | †Diplodocoidea |
| Family: | †Rebbachisauridae |
| Genus: | †Sidersaura Lerzo et al., 2024 |
| Species: | †S. marae
|
| Binomial name | |
| †Sidersaura marae Lerzo et al., 2024
| |
Discovery and naming
editThe Sidersaura fossil material was discovered in 2012 in sediments from the base of the Huincul Formation (Barda Atravesada de Las Campanas locality) in Cañadón de las Campanas near Villa El Chocón of Neuquén Province, Argentina. The bones were then excavated over the course of five years, during which the holotype of the giant carcharodontosaurid Meraxes was also found.[1][2]
The holotype specimen, MMCh-PV 70, belonging to a mature individual, consists of a braincase fused to the skull roof and partial neurocranium, partial dorsal vertebrae, fourteen caudal vertebrae with some haemal arches, a partial left scapula, right pubic peduncle, part of both tibiae and fibulae, and several bones from the feet, including metatarsals, phalanges, ungual phalanges.[1]
Additional specimens were also assigned as paratypes. MMCh-PV 236, belonging to a mature individual, was found in close proximity to the holotype of Meraxes, about 20 metres (66 ft) from the other Sidersaura specimens. It includes an indeterminate vertebra (likely a sacral or caudal), a dorsal rib, two metacarpals, a partial pelvic girdle including an incomplete ilium, ischia, and pubes, and the left femur and fibula. Additional bones of this specimen, including sacral neural arches, caudal vertebrae, the right femur, left tibia, right fibula, and a metatarsal, have also been found but are currently not prepared. MMCh-PV 307, also from a mature individual, is a partial left fibula. MMCh-PV 309, belonging to a juvenile individual, consists of a dorsal centrum.[1]
In January, 2024, Lerzo et al. described Sidersaura marae as a new genus and species of rebbachisaurid sauropod based on these fossil remains. The generic name, "Sidersaura", combines the Latin word "sidus, sideris", meaning "star"—in reference to the shape of some of the preserved haemal arches—and "saura", the feminine declination of the Greek word "sauros", meaning "lizard" or "reptile". The specific name, "marae", honors fossil preparator and MMCh-PV director Mara Ripoll.[1][3]
Description
editSidersaura was a very large rebbachisaurid. Aside from the controversial giant sauropod Maraapunisaurus which may be a rebbachisaurid, Sidersaura may represent one of the largest known members of this group, at around 18–20 metres (59–66 ft) long and 15 tons in weight.[2][4]
The left femur (MMCh-PV 236) of Sidersaura is 1.55 metres (5.1 ft) long, thus representing the largest known rebbachisaurid femur; other large femurs include those of Limaysaurus, at 1.44 metres (4.7 ft) long, and Comahuesaurus, at 1.13 metres (3.7 ft) long. The femur of Amphicoelias altus, a diplodocid from the Late Jurassic Morrison Formation of the United States estimated at 18 metres (59 ft) in length, was similar in size, at 1.52 metres (5.0 ft).[1][5]
Several unique features are seen in the Sidersaura fossil material that differentiate it from all other species. For example, Sidersaura is the first rebbachisaurid known to have a frontoparietal foramen, a feature otherwise seen only in dicraeosaurids, the related Apatosaurus, and Spinophorosaurus, a basal sauropod. The crescent-shaped calcaneum is different from any other sauropod, more closely resembling basal sauropods such as Vulcanodon than other neosauropods. The haemal arches are also unusual, bearing two sets of projections that give them a star shape. While this is not seen in any other named species, an unnamed rebbachisaurid specimen from the geologically older Candeleros Formation—originally described in 2011 as belonging to a titanosaur—also has a similar haemal arch morphology, indicating the two taxa may be related.[6] Some features of the caudal vertebrae are also seen in titanosaurs, having been previously thought to be synapomorphies of that group.[1]
Classification
edit
Lerzo et al. (2024) recovered Sidersaura as a rebbachisaurid member of the sauropod clade Diplodocoidea, as the sister taxon to Itapeuasaurus in a clade also containing Zapalasaurus. This group is not particularly closely related to Limaysaurus and Cathartesaura (sometimes recovered in a clade called Limaysaurinae), the two other rebbachisaurids named from the Huincul Formation. Sidersaura was one of the last rebbachisaurids known before the clade went extinct at the end of the Turonian age. The results of the phylogenetic analyses of Lerzo et al. are shown in the cladogram below:[1]
Later in 2024, Lerzo et al. described Campananeyen, a rebbachisaurid from the Candeleros Formation. They recovered it as the sister taxon to Sidersaura, with similar phylogenetic relationships to the original Sidersaura description, albeit with Itapeuasaurus as a later diverging taxon.[7]
Palaeoenvironment
edit
Sidersaura is known from the Late Cretaceous Huincul Formation of Río Negro Province, Argentina.[1] Many dinosaurs, including fellow rebbachisaurids (Cathartesaura and Limaysaurus),[8] titanosaurs (Argentinosaurus, Bustingorrytitan, Chucarosaurus, and Choconsaurus),[9] carcharodontosaurids (Mapusaurus, Meraxes, and Taurovenator),[10] a megaraptoran (Aoniraptor), abelisaurids (Skorpiovenator, Tralkasaurus, and Ilokelesia), an elaphrosaurine (Huinculsaurus),[11] a paravian (Overoraptor), and the unusual avetheropod Gualicho have also been named from the formation.[12][13] Remains of unenlagiids, iguanodonts, and elasmarian ornithopods are also known.[14]
References
edit- ^ a b c d e f g h Lerzo, Lucas Nicolás; Gallina, Pablo Ariel; Canale, Juan Ignacio; Otero, Alejandro; Carballido, José Luis; Apesteguía, Sebastián; Makovicky, Peter Juraj (2024-01-03). "The last of the oldies: a basal rebbachisaurid (Sauropoda, Diplodocoidea) from the early Late Cretaceous (Cenomanian–Turonian) of Patagonia, Argentina". Historical Biology: 1–26. doi:10.1080/08912963.2023.2297914. ISSN 0891-2963.
- ^ a b Faigon, Miguel (2023-03-01). "Hallan en Neuquén uno de los últimos dinosaurios de cuello largo y pico de pato". CONICET (in Spanish). Retrieved 2024-01-04.
- ^ Gallina, Pablo A.; Apesteguía, Sebastián (2005). "Cathartesaura anaerobica gen. et sp. nov.,a new rebbachisaurid (Dinosauria, Sauropoda) from the Huincul Formation (Upper Cretaceous), Rio Negro, Argentina". Revista del Museo Argentino de Ciencias Naturales. Nueva Series. 7 (2): 153–166. doi:10.22179/REVMACN.7.332. ISSN 1514-5158.
- ^ Carpenter, Kenneth (2018). "Maraapunisaurus fragillimus, N.G. (formerly Amphicoelias fragillimus), a basal Rebbachisaurid from the Morrison Formation (Upper Jurassic) of Colorado". Geology of the Intermountain West. 5: 227–244. doi:10.31711/giw.v5i0.28.
- ^ Paul, Gregory S. (2016). The Princeton Field Guide to Dinosaurs. Princeton University Press. p. 212. ISBN 978-1-78684-190-2. OCLC 985402380.
- ^ Otero, Alejandro; Canale, Juan Ignacio; Haluza, Alejandro; Calvo, Jorge Orlando (2011-12-01). "New Titanosaur with Unusual Haemal Arches from the Upper Cretaceous of Neuquén Province, Argentina". Ameghiniana. 48 (4): 655–661. doi:10.5710/AMGH.v48i4(482). hdl:11336/95868. ISSN 0002-7014.
- ^ Lerzo, Lucas N.; Fernández-Baldor, Fidel Torcida; Canale, Juan I.; Whitlock, John A.; Otero, Alejandro; Gallina, Pablo A. (2024-08-13). "They all floated in the Cretaceous: new rebbachisaurid (Sauropoda, Diplodocoidea) with a highly pneumatized skeleton from the Upper Cretaceous (lower Cenomanian) of Patagonia, Argentina". Historical Biology: 1–14. doi:10.1080/08912963.2024.2383708. ISSN 0891-2963.
- ^ Calvo, Jorge O.; Salgado, Leonardo (1995). "Rebbachisaurus tessonei sp. nov. a new Sauropoda from the Albian-Cenomanian of Argentina; new evidence on the origin of the Diplodocidae" (PDF). Gaia. 11: 13–33. Archived from the original (PDF) on 23 September 2021.
- ^ Simón, M. E.; Salgado, L. (2023). "A new gigantic titanosaurian sauropod from the early Late Cretaceous of Patagonia (Neuquén Province, Argentina)". Acta Palaeontologica Polonica. doi:10.4202/app.01086.2023.
- ^ Canale, Juan I.; Apesteguía, Sebastián; Gallina, Pablo A.; Mitchell, Jonathan; Smith, Nathan D.; Cullen, Thomas M.; Shinya, Akiko; Haluza, Alejandro; Gianechini, Federico A.; Makovicky, Peter J. (July 2022). "New giant carnivorous dinosaur reveals convergent evolutionary trends in theropod arm reduction". Current Biology. 32 (14): 3195–3202.e5. Bibcode:2022CBio...32E3195C. doi:10.1016/j.cub.2022.05.057. PMID 35803271. S2CID 250343124.
- ^ Baiano, Mattia A.; Coria, Rodolfo A.; Cau, Andrea (June 2020). "A new abelisauroid (Dinosauria: Theropoda) from the Huincul Formation (lower Upper Cretaceous, Neuquén Basin) of Patagonia, Argentina". Cretaceous Research. 110: 104408. Bibcode:2020CrRes.11004408B. doi:10.1016/j.cretres.2020.104408. S2CID 214118853.
- ^ Cerroni, M.A.; Motta, M.J.; Agnolín, F.L.; Aranciaga Rolando, A.M.; Brissón Egli, F.; Novas, F.E. (2020). "A new abelisaurid from the Huincul Formation (Cenomanian-Turonian; Upper Cretaceous) of Río Negro province, Argentina". Journal of South American Earth Sciences. 98: 102445. Bibcode:2020JSAES..9802445C. doi:10.1016/j.jsames.2019.102445. S2CID 213781725.
- ^ Matías J. Motta; Federico L. Agnolín; Federico Brissón Egli; Fernando E. Novas (2020). "New theropod dinosaur from the Upper Cretaceous of Patagonia sheds light on the paravian radiation in Gondwana". The Science of Nature. 107 (3): Article number 24. Bibcode:2020SciNa.107...24M. doi:10.1007/s00114-020-01682-1. hdl:11336/135530. PMID 32468191. S2CID 218913199.
- ^ Agnolin, Federico L.; Gonzalez Riga, Bernardo J.; Aranciaga Rolando, Alexis M.; Rozadilla, Sebastián; Motta, Matías J.; Chimento, Nicolás R.; Novas, Fernando E. (2023-02-02). "A new giant titanosaur (Dinosauria, Sauropoda) from the Upper Cretaceous of Northwestern Patagonia, Argentina". Cretaceous Research. 146: 105487. Bibcode:2023CrRes.14605487A. doi:10.1016/j.cretres.2023.105487. ISSN 0195-6671.