Aeolosaurus

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Aeolosaurus
Temporal range:
Ma
Life reconstruction of Aeolosaurus rionegrinus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: †Sauropodomorpha
Clade: †Sauropoda
Clade: †Macronaria
Clade: †Titanosauria
Clade: †Lithostrotia
Clade: †Aeolosaurini
Genus: †Aeolosaurus
Powell, 1987
Type species
†Aeolosaurus rionegrinus
Powell, 1987
Other species
  • †A. colhuehuapensis
    Casal et al., 2007

Aeolosaurus (

quadrupedal herbivore
with a long neck and tail. Aeolosaurus is well known for a titanosaur, as it is represented by the remains of several individuals belonging to at least two species. However, like most titanosaurs, no remains of the skull are known. The holotype of Aeolosaurus rionegrinus consists of a series of seven tail vertebrae, as well as parts of both forelimbs and the right hindlimb. It was discovered in the Angostura Colorada Formation in Argentina, which dates from the Campanian stage of the Late Cretaceous, about 83 to 74 million years ago. The species A. maximus was transferred over to the new genus Arrudatitan in 2021.[1]

Etymology

This dinosaur is named after the

paleontologist Jaime Powell in 1987.[2]

Provenance

Aeolosaurus is a widespread genus of titanosaur known from the Late Cretaceous of South America. Fossils have been collected from the Allen, Angostura Colorada, Lago Colhué Huapí, and Los Alamitos Formations of Argentina and the Serra da Galga Formation of Brazil.[3] All Aeolosaurus fossils are from the Campanian and Maastrichtian ages of the Cretaceous period.

History

The type species of Aeolosaurus, Aeolosaurus rionegrinus, was originally named along with the genus in the doctoral thesis of Jaime E. Powell. However, according to the ICZN, names from dissertations are not valid, so it was not formally named until it was published the following year.[2][4] Powell's thesis was ultimately published in 2003, which is sometimes incorrectly cited as having named the genus.[4][5] In 2004, Aeolosaurus and Gondwanatitan were recognized as forming a new group of titanosaurs, which was named Aeolosaurini.[6] In 2007, a second species, A. colhuehuapensis was named, also from Patagonia.[7] A third species, A. maximus, was named in 2011.[3] A. maximus was moved to the genus Arrudatitan in 2021.

Description

Like all sauropods, Aeolosaurus was a large, long-necked, quadrupedal herbivore. A. rionegrinus was roughly 14 meters (46 ft) long and 6 tonnes (6.6 short tons) in weight according to Gregory S. Paul.[8] In 2020 Molina-Pérez and Larramendi gave a larger estimation of 18.1 meters (60 ft) and 14.7 tonnes (16.2 short tons).[9] A. rionegrinus was heavily built for a titanosaur, with limb bones similar in robustness to those of Saltasaurus.[3]

Aeolosaurs, Aeolosaurus in particular, have very distinctive caudal vertebrae. The genus Aeolosaurus is diagnosed by the shared presence of down-curved prezygapophyses on its anterior caudal vertebrae and chevrons from the anterior and middle portions of the tail with concave posterodorsal surfaces that contain double articular facets.

neural spines angled anteriorly when the vertebrae are aligned.[11] These vertebrae resemble those of Cedarosaurus, Venenosaurus, and Gondwanatitan.[11] The tail of Aeolosaurus was apparently curved strongly downward, a trait likely shared with other members of Aeolosaurini.[12] This curvature would likely have led to the posterior portion of the tail being very low to the ground, though likely not touching it. The curved base of the tail may have enabled the m. caudofemoralis longus, which extended from the femur to the tail vertebrae, to exert more force while retracting the hindlimb.[12]

Aeolosaurus, like many lithostrotian titanosaurs, bore osteoderms.[13] However, its osteoderms were unusual and most closely resemble those of Mendozasaurus.[14] As in all osteoderm-bearing titanosaurs, the osteoderms were probably arranged in one or two rows along the flanks.

Classification

Aeolosaurus is most closely related to the genera Gondwanatitan and Panamericansaurus.[15][16] Together with Gondwanatitan, it defines the clade Aeolosaurini.[6] The two Aeolosaurus species from Argentina, A. rionegrinus and A. colhuehuapensis, appear to be more closely related to each other than to the Brazilian species A. maximus.[3]

Aeolosaurus sp. tail vertebrae

The classification of Aeolosaurus and its relatives is heavily based on features of the tail vertebrae, which are the only bones preserved in most aeolosaurs.[3]

Aeolosaurus has been included in several cladistic analyses. The phylogeny of Aeolosaurini here is based on Gallina and Otero 2015, with the application of clade names according to their phylogenetic definitions.[3][6][16][17][18]

Aeolosaurini

Species

There are currently two named valid species of Aeolosaurus, as well as several specimens that have been referred to the genus but not given a species. In addition, Gondwanatitan faustoi, the closest known relative of the genus, has been proposed to represent an additional species of Aeolosaurus, as Aeolosaurus faustoi.[19] However, Gondwanatitan is typically considered a distinct genus.[4]

  • Aeolosaurus rionegrinus is the type species of Aeolosaurus.[2] It is known from a single specimen, MJG-R 1, that consists of seven caudal vertebrae and many appendicular elements.[5] Its limb bones suggest that it was heavily built, similar to Saltasaurus. It is found in the Angostura Colorada Formation of Argentina.
  • Aeolosaurus colhuehuapensis is known only from 21 caudal vertebrae.
    Lago Colhue Huapi Formation of Argentina.[20]
Aeolosaurus sp. forelimb elements

Another specimen, described in 1993, consists of five tail vertebrae, and some bones from the forelimb and pelvis. Since there are two right ulna (forearm) bones, the specimen must consist of at least two individuals. These bones were also associated with two osteoderms, or bony armor plates, providing evidence that this dinosaur was armored. This specimen is from the Allen Formation of Rio Negro, dating back about 70 to 68 million years ago to the middle Maastrichtian stage. While this specimen bears features that characterize the genus Aeolosaurus, it is from a younger time period and shows enough differences that the authors recognized it as a possible second species.[13] Additional material from the same quarry, described in 2013, shows that the quarry contained the remains at least three individuals of Aeolosaurus.[21]

Another partial skeleton, including four more tail vertebrae and material from both limbs on the left side of the body, was described in 1997. This was recovered from the Los Alamitos Formation of Rio Negro, which falls between the other two dates. This specimen was also referred to the genus Aeolosaurus, but not to the species A. rionegrinus, and may represent a third species.[22]

However, since the genus Aeolosaurus is not well known, the authors chose not to formally name either of these possible new species. For now, they are both simply known as "Aeolosaurus sp." Future discoveries may give scientists more information on variation within the genus, and show that all of the above specimens belong to A. rionegrinus, or that they merit being formally named.

A middle caudal vertebra from the Serra da Galga Formation, CPP 248, cannot be evaluated for any diagnostic features of the genus Aeolosaurus.[4] However, because it clearly does not belong to Gondwanatitan, it is most likely that this vertebra represents Aeolosaurus, a genus otherwise unknown from the Serra da Galga Formation.[3]

Another series of 15 tail vertebrae was assigned to Aeolosaurus in the original description, but it was later determined that the series does not belong to this genus, as it lacks several features found in the other specimens of Aeolosaurus.[2][13]

Paleoecology

Aeolosaurus lived during the

Rocasaurus muniozi, as well as hadrosaurs and ankylosaurs.[21]

Aeolosaurus compared to dinosaur fauna from the Allen Formation (Aeolosaurus in light green, fourth from left)

References

  1. S2CID 235526860
    .
  2. ^ a b c d Powell, Jaime Eduardo (1987). "The Late Cretaceous fauna of Los Alamitos, Patagonia, Argentina. Part VI. The titanosaurids". Revista del Museo Argentino de Siencias Naturales. 3: 111–142.
  3. ^
    doi:10.11646/zootaxa.3085.1.1
    .
  4. ^
    doi:10.4013/gaea.2011.71.03
    .
  5. ^ a b c Powell, Jaime Eduardo (2003). "Revision of South American titanosaurid dinosaurs: palaeobiological, palaeobiogeographical, and phylogenetic aspects". Records of the Queen Victoria Museum. 111.
  6. ^
    doi:10.4072/rbp.2004.3.04
    .
  7. ^
    doi:10.4072/rbp.2007.1.05
    .
  8. ^ Paul, G. S. (2010). The Princeton Field Guide to Dinosaurs. Princeton University Press.
  9. Bibcode:2020dffs.book.....M
    .
  10. ^ Kellner, Alexander W. A.; de Azevedo, Sergio A. K. (1999). "A new sauropod dinosaur (Titanosauria) from the Late Cretaceous of Brazil". National Science Museum Monographs. 15: 111–142.
  11. ^ a b c d e Tidwell, Virginia; Carpenter, Kenneth; Meyer, S. (2001). "New titanosauriform (Sauropoda) from the Poison Strip Member of the Cedar Mountain Formation (Lower Cretaceous), Utah". In Tanke, D. H.; Carpenter, Kenneth (eds.). Mesozoic Vertebrate Life. Indiana University Press. pp. 139–165.
  12. ^
    S2CID 218822392
    .
  13. ^ a b c Salgado, Leonardo; Coria, Rodolfo A. (1993). "El genero Aeolosaurus (Sauropoda, Titanosauridae) en la Formacion Allen (Campaniano-Maastrichtiano) de la provincia de Rio Negro, Argentina". Ameghiniana. 30 (2): 119–128.
  14. PMID 25118985
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  15. PMID 25250458
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  16. ^
    S2CID 131595654
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  17. ^ Calvo, J. O.; González-Riga, B. J.; Porfiri, J. D. (2007). "A new titanosaur sauropod from the Late Cretaceous of Neuquén, Patagonia, Argentina". Arquivos do Museu Nacional, Rio de Janeiro. 65 (4): 485–504.
  18. PMID 17768539
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  19. doi:10.25249/0375-7536.2001313307314 (inactive 2024-04-25).{{cite journal}}: CS1 maint: DOI inactive as of April 2024 (link
    )
  20. ^ Casal GA, Allard JO and Foix N (2015) Análisis estratigráfico y paleontológico del Cretácico Superior en la Cuenca del Golfo San Jorge: nueva unidad litoestratigráfica para el Grupo Chubut. Revista de la Asociación Geológica Argentina 72: 77–95.
  21. ^
    doi:10.4202/app.2011.0055
    .
  22. ^ Salgado, L.; Coria, R. A.; Calvo, J. O. (1997). "Presence of the genus Aeolosaurus (Sauropoda, Titanosauridae) in the Los Alamitos Formation (Late Cretaceous) of the Rio Negro Province". Revista Guarulhos - Geociencias. 2 (2): 44–49.
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