A computer model of the skeleton and muscles estimated this dinosaur had a maximum speed of 7 km/h (5 mph) with a pace, a gait where the fore and hind limb of the same side of the body move simultaneously.

The fossils of Argentinosaurus were recovered from the Huincul Formation, which was deposited in the middle Cenomanian to early Turonian ages (about 96 to 92 million years ago) and contains a diverse dinosaur fauna including the giant theropod Mapusaurus.

The formal description was published in 1993 by Bonaparte and the Argentine palaeontologist Rodolfo Coria, with the naming of a new genus and species, Argentinosaurus huinculensis.

[5][6] In 1996, Bonaparte referred (assigned) a complete femur (thigh bone) from the same locality to the genus, which was put on exhibit at the Museo Carmen Funes.

In their 2004 study, Mazzetta and colleagues mentioned an additional femur that is housed in the La Plata Museum under the specimen number MLP-DP 46-VIII-21-3.

[5] In 2013, Sellers and colleagues estimated a mass of 83.2 tonnes (91.7 short tons) by calculating the volume of the aforementioned Museo Carmen Funes skeleton.

[20] In the same year, Paul moderated his earlier estimate from 1994 and listed the body mass of Argentinosaurus at more than 50 tonnes (55 short tons).

Puertasaurus, Futalognkosaurus, Dreadnoughtus, Paralititan, "Antarctosaurus" giganteus, and Alamosaurus have all been considered to be comparable in size with Argentinosaurus by some studies,[22][23] although others have found them to be notably smaller.

[13][24][7] In 2017, Carballido and colleagues considered Argentinosaurus to be smaller than Patagotitan, since the latter had a greater area enclosed by the neural spine, diapophyses, and parapophyses of its anterior dorsal vertebrae.

Dissenting configurations were suggested by Bonaparte and Coria in 1993; Fernando Novas and Martín Ezcurra in 2006; and Leonardo Salgado and Jaime Powell in 2010.

[2][34][1] Another contentious issue is the presence of hyposphene-hypantrum articulations, accessory joints between vertebrae that were located below the main articular processes.

Difficulties in interpretation arise from the fragmentary preservation of the vertebral column; these joints are hidden from view in the two connected vertebrae.

[29] Other authors argued most titanosaur genera lacked hyposphene-hypantrum articulations and that the articular structures seen in Epachthosaurus and Argentinosaurus are thickened vertebral laminae (ridges).

When it was identified as a tibia, it was thought to have a comparatively short cnemial crest, a prominent extension at the upper front that anchored muscles for stretching the leg.

However, as stated by Mazzetta and colleagues, this bone lacks both the proportions and anatomical details of a tibia, while being similar in shape to other sauropod fibulae.

As these articulations were also present in the titanosaurids Andesaurus and Epachthosaurus, Bonaparte and Coria proposed a separate family for the three genera, the Andesauridae.

[40] In 2002, Davide Pisani and colleagues recovered Argentinosaurus as a member of Titanosauria, and again found it to be in a clade with Opisthocoelicaudia and an unnamed taxon, in addition to Lirainosaurus.

[41] A 2003 study by Jeffrey Wilson and Paul Upchurch found both Titanosauridae and Andesauridae to be invalid; the Titanosauridae because it was based on the dubious genus Titanosaurus and the Andesauridae because it was defined on plesiomorphies (primitive features) rather than on synapomorphies (newly evolved features that distinguish the group from related groups).

[39] A 2011 study by Philip Mannion and Calvo found Andesauridae to be paraphyletic (excluding some of the group's descendants) and likewise recommended its disuse.

[47] Another 2018 study by Hesham Sallam and colleagues found two different phylogenetic positions for Argentinosaurus based on two data sets.

[8] Rinconsaurus Muyelensaurus Aeolosaurus Overosaurus Bonitasaura Notocolossus Mendozasaurus Futalognkosaurus Quetecsaurus Puertasaurus Drusilasaura Patagotitan Argentinosaurus Topology according to González Riga and colleagues, 2019.

Advantages of giant sizes would likely have included the ability to keep food inside the digestive tract for lengthy periods to extract a maximum of energy, and increased protection against predators.

Mapusaurus is known from at least seven individuals found together,[53] raising the possibility that this theropod hunted in packs to bring down large prey including Argentinosaurus.

The computer model was based on a laser scan of a mounted skeletal reconstruction on display at the Museo Carmen Funes.

Muscles and their properties were based on comparisons with living animals; the final model had a mass of 83 tonnes (91 short tons).

The optimal gait found by the algorithms was close to a pace (forelimb and hind limb on the same side of the body move simultaneously).

A study of the El Zampal section of the formation found hornworts, liverworts, ferns, Selaginellales, possible Noeggerathiales, gymnosperms (including gnetophytes and conifers), and angiosperms (flowering plants), in addition to several pollen grains of unknown affinities.

[59] The Huincul Formation is among the richest Patagonian vertebrate associations, preserving fish including dipnoans and gar, chelid turtles, squamates, sphenodonts, neosuchian crocodilians, and a wide variety of dinosaurs.

[61] In addition to Argentinosaurus, the sauropods of the Huincul Formation are represented by another titanosaur, Choconsaurus,[62] and several rebbachisaurids including Cathartesaura,[63] Limaysaurus,[64][65] and some unnamed species.