Aeolosaurus

*Aeolosaurus rionegrinus*

***Aeolosaurus*** (pronounced /ˌiː.əlɵˈsɔrəs/; "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. The remains of this dinosaur are incomplete, so size can only be estimated but *Aeolosaurus* was probably at least 45 feet (14 meters) in length. 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 three 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.

## 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.

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.

## Provenance

Aeolosaurus is a widespread genus of titanosaur known from the Late Cretaceous of South America. Fossils have been collected from the Allen, Angostura Colorado, Bajo Barreal, and Los Alamitos Formations of Argentina and the Adamantina Formation and Marilla 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

Relationships among the many titanosaurian sauropods are hazy at best, but *Aeolosaurus* has been tentatively linked to a few other genera, based on features of the tail vertebrae, including *Rinconsaurus* and *Adamantisaurus*. *Gondwanatitan* and *Aeolosaurus* both exhibit neural spines on the tail vertebrae that point forwards, a feature not seen in any other known titanosaurians

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*.*Venenosaurus* also had depression-like fossae, but its "depressions" penetrated deeper into the vertebrae, were divided into two chambers, and extend farther into the vertebral columns.

Its middle tail vertebrae's neural spines angled anteriorly when the vertebrae are aligned. These vertebrae resemble those of *Cedarosaurus*, *Venenosaurus*, and *Gondwanatitan*.

## Classification

Aeolosaurus is most closely related to the genera Gondwanatitan and Panamericansaurus. Together with Gondwanatitan, it defines the clade Aeolosaurini. 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.

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.

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.

## Paleoecology

Aeolosaurus lived during the Campanian and Maastrichtian ages of the Late Cretaceous and shared its environment with hadrosaurs. The unnamed Allen Formation species of Aeolosaurus inhabited an environment that it shared with five other species of titanosaur, including Rocasaurus muniozi, as well as hadrosaurs and ankylosaurs.

## JPInstitute.com Description

Aeolosaurus was a member of the long-necked, plant-eating titanosaur family. Although it was small for a titanosaur, it was still quite large, and like some of the other smaller titanosaurs, it had bony plates on its back to protect it from the bite of large meat-eaters that would have attacked from above.

Known from several partial skeletons, Aeolosaurus is the first known titanosaur from fossil-rich Patagonia to exhibit dermal plates. An interesting note is that unusually thick egg shells with strange dome shapes on the surface were found associated with this dinosaur's fossil material.

## Links

http://web.archive.org/web/20031006055639/http://www.jpinstitute.com/dinopedia/dinocards/dc\_aeolo.html