Size and Weight:
As you may have guessed from its name, the remains of Argentinosaurus were discovered in present-day Argentina, in South America. To date, researchers haven't found an entire skeleton, but what they have found--four-foot long vertebrae and five-foot-long tibiae--indicate that Argentinosaurus was a truly titanic sauropod (hence its classification in some circles as a titanosaur, a lightly armored descendant of the sauropods). Just how big was Argentinosaurus? Well, some reliable estimates place this dinosaur at 100 feet from head to tail and over 100 tons! See more facts and figures about Argentinosaurus and a gallery of Argentinosaurus pictures
Interestingly, the remains of Argentinosaurus were dug up near the fossils of another huge dinosaur--the carnivorous theropod Giganotosaurus. This has led paleontologists (and TV producers) to speculate that packs of Giganotosaurus may have hunted down full-grown Argentinosaurus adults--a chase that would certainly have been deadly for any smaller creatures that happened to get in the way. (See Giganotosaurus vs. Argentinosaurus - Who Wins? for an analysis of this hypothetical encounter.)
The status of Argentinosaurus as the largest dinosaur that ever lived is constantly in jeopardy. Paleontologists in India have uncovered the remains of another plant-eater, Bruhathkayosaurus, that may have been even bigger than Argentinosaurus; the trouble is, no one is exactly sure what type of dinosaur Bruhathkayosaurus was. Another possible usurper of Argentinosaurus' throne is the equally mysterious Amphicoelias, from North America, which some paleontologists say measured 200 feet long and weighed as much as 125 tons. Those are impressive numbers, to be sure, but until more supporting evidence is found Argentinosaurus remains the largest identified dinosaur.