Titanosauria in the context of "Alamosaurus"

Argentinosaurus (meaning "lizard from Argentina") is a genus of giant sauropod dinosaur that lived during the Late Cretaceous period in what is now Argentina. Although it is only known from fragmentary remains, Argentinosaurus is one of the largest known land animals of all time, perhaps the largest, measuring 30–35 m (98–115 ft) long and weighing 65–80 t (72–88 short tons). It was a member of Titanosauria, the dominant group of sauropods during the Cretaceous.

The first Argentinosaurus bone was discovered in 1987 by a farmer on his farm near the city of Plaza Huincul. A scientific excavation of the site led by the Argentine palaeontologist José Bonaparte was conducted in 1989, yielding several back vertebrae and parts of a sacrum—fused vertebrae between the back and tail vertebrae. Additional specimens include a complete femur (thigh bone) and the shaft of another. Argentinosaurus was named by Bonaparte and the Argentine palaeontologist Rodolfo Coria in 1993; the genus contains a single species, A. huinculensis, after its place of discovery, Plaza Huincul.

Dreadnoughtus is a genus of titanosaurian sauropod dinosaur containing a single species, Dreadnoughtus schrani. It is known from two partial skeletons discovered in Upper Cretaceous (Campanian to Maastrichtian, approximately 76–70 million years ago) rocks of the Cerro Fortaleza Formation in Santa Cruz Province, Argentina. It is one of the largest terrestrial vertebrates known, with the immature type specimen measuring 26 metres (85 ft) in total body length and weighing 48–49 metric tons (53–54 short tons) (the greatest mass of any land animal that can be calculated with reasonable certainty).

Dreadnoughtus is known from more complete skeletons than any other gigantic titanosaurian. Drexel University paleontologist Kenneth Lacovara, who discovered the genus, chose the name Dreadnoughtus, which means "fears nothing", stating "I think it's time the herbivores get their due for being the toughest creatures in an environment." Specifically, the name was inspired by the dreadnought, an extremely influential early 20th-century battleship type, known for revolutionarily outclassing (and thus supposedly never needing to fear) the smaller, weaker battleships that came before.