Aeolosaurus (; "Aeolus' lizard") is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. Like most sauropods, it would have been a 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.
Etymology
This dinosaur is named after the Greek mythological figure Aeolus, Keeper of the Winds in Homer's Odyssey, because of the frequent winds that blow across Patagonia, where the remains were found. The generic name also includes the Greek sauros ('lizard'), the traditional suffix used in dinosaur names. The specific name (A. rionegrinus), refers to its location, in the Rio Negro Province of Argentina. Both genus and species were named and described by Argentine paleontologist Jaime Powell in 1987.
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. 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. Powell's thesis was ultimately published in 2003, which is sometimes incorrectly cited as having named the genus. In 2004, Aeolosaurus and Gondwanatitan were recognized as forming a new group of titanosaurs, which was named Aeolosaurini. In 2007, a second species, A. colhuehuapensis was named, also from Patagonia. A third species, A. maximus, was named in 2011. 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. In 2020 Molina-Pérez and Larramendi gave a larger estimation of 18.1 meters (60 ft) and 14.7 tonnes (16.2 short tons). A. rionegrinus was heavily built for a titanosaur, with limb bones similar in robustness to those of Saltasaurus.
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. The caudal vertebrae of Aeolosaurus and the related genus Gondwanatitan share anteriorly-inclined neural spines in the anterior caudal vertebrae. The vertebrae from the middle part of its tail had elongated centra. Aeolosaurus had vertebral lateral fossae that resembled shallow depressions. Fossae that similarly resemble shallow depressions are known from Saltasaurus, Alamosaurus, Malawisaurus, and Gondwanatitan. Its middle tail vertebrae's neural spines angled anteriorly when the vertebrae are aligned. These vertebrae resemble those of Cedarosaurus, Venenosaurus, and Gondwanatitan. The tail of Aeolosaurus was apparently curved strongly downward, a trait likely shared with other members of Aeolosaurini. 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.
Aeolosaurus, like many lithostrotian titanosaurs, bore osteoderms. However, its osteoderms were unusual and most closely resemble those of Mendozasaurus. As in all osteoderm-bearing titanosaurs, the osteoderms were probably arranged in one or two rows along the flanks.