Pilmatueia is a diplodocoid sauropod belonging to the family Dicraeosauridae that lived in Argentina during the Early Cretaceous. Its type and only species is Pilmatueia faundezi. Pilmatueia was probably closely related to other South American dicraeosaurids such as Amargasaurus. Pilmatueia had relatively pneumatic vertebrae compared to other dicraeosaurids, which were otherwise characterized by a reduction in pneumaticity relative to other sauropods. Pilmatueia dates to the Valanginian, an age of the Cretaceous period for which dinosaur faunas are poorly known.
| Pilmatueia Temporal range: Early Cretaceous,
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|---|---|
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Superfamily: | †Diplodocoidea |
| Family: | †Dicraeosauridae |
| Genus: | †Pilmatueia Coria et al., 2019 |
| Type species | |
| †Pilmatueia faundezi Coria et al., 2019
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Discovery and naming
editFossils of Pilmatueia faundezi were discovered in Neuquén Province, Argentina, at a site called Pilmatué.[1] Fossil excavations at Pilmatué began in 2009, [2] and the discovery of dicraeosaurid remains at Pilmatué was first announced in 2012, at a paleontology conference in Buenos Aires.[3][1] In 2019,[a] Rodolfo Coria and colleagues named the new genus and species Pilmatueia faundezi. The genus name refers to the Pilmatué locality, and the species epithet recognizes Ramón Faúndez, manager of the Museo Municipal de Las Lajas, who supported the excavation project. The discovery of Pilmatueia in the Valanginian, an age of the Early Cretaceous with poorly known dinosaur faunas, helped fill a gap in the dicraeosaurid fossil record between Jurassic dicraeosaurids and the later Amargasaurus.[1]
Fossil specimens
editPilmatueia faundezi fossils have been found in the Mulichinco Formation of Argentina. Known material includes the holotype, MLL Pv-005, a posterior dorsal vertebra;[1] the paratype MLL-Pv-002, a posterior cervical vertebra; MLL-Pv-010, a partial skeleton including cervical vertebrae, dorsal vertebrae, ribs, a caudal vertebra, and incomplete scapulae;[4] and other isolated vertebrae.[1] Other dicraeosaurid fossils have been found in the Mulichinco Formation, including a femur[1] and a natural cranial endocast,[5] and it is possible that they also belong to Pilmatueia faundezi.[1][6]
Description
editPilmatueia, like other dicraeosaurids, had tall, deeply forked neural spines on its cervical and dorsal vertebrae. The cervical neural spines were low compared to those of Amargasaurus and Bajadasaurus.[4] As in most dicraeosaurids, the neural spines were inclined forward, unlike the backswept neural spines seen in Amargasaurus.[4] Unlike most dicraeosaurids, which have reduced vertebral pneumaticity compared to other sauropods, the cervical vertebrae of Pilmatueia contain pneumatic chambers. However, as in other dicraeosaurids, the dorsal centra lack the pneumatic foramina that are characteristic of most sauropods.[7][8] The cervical centra have ventral keels that are forked anteriorly and posteriorly, unlike the simple midline keels typical of other diplodocoids.[4] A foramen is present on the proximal end of the cervical ribs, which probably is a nutrient foramen and not a pneumatic structure. The anterior dorsal vertebrae show an autapomorphic ridge on the anterior centrodiapophyseal lamina.[1] Even the posterior dorsal vertebrae had forked neural spines, as in its close relative Amargasaurus, and unlike other dicraeosaurids in which forking of the neural spines only extended into the middle dorsal vertebrae.[4] The posterior dorsal vertebrae show an autapomorphic pair of deep fossae near the bases of the neural spines.[1] The scapula has a ridge on the medial surface near the acromion, which is not present in other dicraeosaurids.[4]
Classification
edit| Phylogenetic position of Pilmatueia within Dicraeosauridae, following an analysis by Windholtz et al. that recovered their favored hypothesis of South American dicraeosaurid monophyly,[4] with South American dicraeosaurids highlighted in red. |
Pilmatueia is a dicraeosaurid sauropod. Its phylogenetic position within Dicraeosauridae is uncertain, with some analyses finding it to be closely related to Amargasaurus[1][4] and other analyses finding it to be a more basal dicraeosaurid, outside the clade uniting Dicraeosaurus, Brachytrachelopan, and Amargasaurus.[9][10][4] Windholz et al. argued that, while phylogenetic analyses do not currently provide clear resolution for its affinities, on chronological and biogeographic grounds it is most likely to belong to a clade uniting the South American dicraeosaurids.[4]
Paleoecology
editPilmatueia lived in what is now Argentina during the Valanginian age of the Cretaceous, and is a member of the Bajadan faunal assemblage. It coexisted with an indeterminate species of diplodocid[6] and the small, early carcharodontosaur Lajasvenator.[2] Podocarp trees were present in the ecosystem.[11]
Footnotes
edit- ^ The article was released online on 29 August 2018, but formally published in the January 2019 issue of the journal.
References
edit
- ^ a b c d e f g h i j Rodolfo A. Coria; Guillermo J. Windholz; Francisco Ortega; Philip J. Currie (2018). "A new dicraeosaurid sauropod from the Lower Cretaceous (Mulichinco Formation, Valanginian, Neuquén Basin) of Argentina". Cretaceous Research. 93: 33–48. Bibcode:2019CrRes..93...33C. doi:10.1016/j.cretres.2018.08.019. S2CID 135017018.
- ^ a b Coria, Rodolfo A.; Currie, Philip J.; Ortega, Francisco; Baiano, Mattia A. (2019-11-25). "An Early Cretaceous, medium-sized carcharodontosaurid theropod (Dinosauria, Saurischia) from the Mulichinco Formation (upper Valanginian), Neuquén Province, Patagonia, Argentina". Cretaceous Research. 111: 104319. doi:10.1016/j.cretres.2019.104319. hdl:11336/122794. ISSN 0195-6671. S2CID 214475057.
- ^ Coria, R. A.; Ortega, F.; Succar, C.; Currie, P.; Koppelhus, E. (2012). "First record of a dicraeosaurid sauropod from the Lower Cretaceous (Valanginian) of Neuquén Basin". Ameghiniana. 49 (4R): R44.
- ^ a b c d e f g h i j Windholz, Guillermo J; Coria, Rodolfo A.; Bellardini, Flavio; Baiano, Mattia A.; Pino, Diego; Ortega, Francisco; Currie, Philip J. (2022-12-21). "On a dicraeosaurid specimen from the Mulichinco Formation (Valanginian, Neuquén Basin) of Argentina and phylogenetic relationships of the South American dicraeosaurids (Sauropoda, Diplodocoidea)". Comptes Rendus Palevol. 21 (45): 991–1019. ISSN 1631-0683.
- ^ Paulina Carabajal, A.; Coria, R.A.; Currie, P.J.; Koppelhus, E.B. (2017-12-12). "A natural cranial endocast with possible dicraeosaurid (Sauropoda, Diplodocoidea) affinities from the Lower Cretaceous of Patagonia". Cretaceous Research. 84: 437–441. doi:10.1016/j.cretres.2017.12.001. hdl:11336/86084. ISSN 0195-6671.
- ^ a b Gallina, Pablo A.; Apesteguía, Sebastián; Carballido, José L.; Garderes, Juan P. (2022). "Southernmost spiny backs and whiplash tails: flagellicaudatans from South America". In Otero, Alejandro; Carballido, José L.; Pol, Diego (eds.). South American Sauropodomorph Dinosaurs. Cham: Springer International Publishing. pp. 209–236. ISBN 978-3-030-95958-6.
- ^ Windholz, Guillermo J.; Coria, Rodolfo A.; Zurriaguz, Virginia L. (2019-11-29). "Vertebral pneumatic structures in the Early Cretaceous sauropod dinosaur Pilmatueia faundezi from northwestern Patagonia, Argentina". Lethaia. 53 (3): 369–381. doi:10.1111/let.12363. ISSN 0024-1164. S2CID 212766423.
- ^ Windholz, Guillermo J.; Carballido, José L.; Coria, Rodolfo A.; Zurriaguz, Virginia L.; Rauhut, Oliver W. M. (2022-11-22). "How pneumatic were the presacral vertebrae of dicraeosaurid (Sauropoda: Diplodocoidea) dinosaurs?". Biological Journal of the Linnean Society. 138: 103–120. doi:10.1093/biolinnean/blac131. ISSN 0024-4066.
- ^ Gallina, Pablo A.; Apesteguía, Sebastián; Canale, Juan I.; Haluza, Alejandro (2019-02-04). "A new long-spined dinosaur from Patagonia sheds light on sauropod defense system". Scientific Reports. 9 (1): 1392. Bibcode:2019NatSR...9.1392G. doi:10.1038/s41598-018-37943-3. ISSN 2045-2322. PMC 6362061. PMID 30718633. S2CID 59603627.
- ^ Whitlock, John A.; Wilson Mantilla, Jeffrey A. (2020-12-23). "The Late Jurassic sauropod dinosaur 'Morosaurus' agilis Marsh, 1889 reexamined and reinterpreted as a dicraeosaurid". Journal of Vertebrate Paleontology. 40 (6): e1780600. Bibcode:2020JVPal..40E0600W. doi:10.1080/02724634.2020.1780600. eISSN 1937-2809. ISSN 0272-4634. S2CID 234424022.
- ^ Gnaedinger, Silvia; Coria, Rodolfo A.; Koppelhus, Eva; Casadío, Silvio; Tunik, Maisa; Currie, Philip (2017). "First Lower Cretaceous record of Podocarpaceae wood associated with dinosaur remains from Patagonia, Neuquén Province, Argentina". Cretaceous Research. 78: 228–239. Bibcode:2017CrRes..78..228G. doi:10.1016/j.cretres.2017.06.014. hdl:11336/30408. ISSN 0195-6671.