Aeolosaurus

Aeolosaurus (/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 m) in length.

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.

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.[1] Gondwanatitan and Aeolosaurus both exhibit neural spines on the tail vertebrae that point forwards, a feature not seen in any other known titanosaurians [2]

The vertebrae from the middle part of its tail had elongated centra.[3] Aeolosaurus had vertebral lateral fossae that resembled shallow depressions.[4] Fossae that similarly resemble shallow depressions are known from Saltasaurus, Alamosaurus, Malawisaurus, and Gondwanatitan.[4] 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.[4]

Its middle tail vertebrae's neural spines angled anteriorly when the vertebrae are aligned.[5] These vertebrae resemble those of Cedarosaurus, Venenosaurus, and Gondwanatitan.

Possible additional species
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.[6]

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 [7]

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.

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.