What was the largest dinsoaur to ever walk on earth?

Answer 1

The heaviest dinosaur known from fairly complete and reliable remains is Argentinosaurus, at around 80 tons or so. There is some (poor) evidence that still larger sauropods existed, Bruhathkayosaurus may have been some 140 tons or more (some claim over 200 tons, which would mean that it rivaled blue whales with respect to sheer weight), and Amphicoelias may have been over 60 meters in length, but it was a slender animal by sauropod standards, weighing "only" 120 tons. However, Amphicoelias is only known from sketches (the original fossil material was lost) and Bruhathkayosaurus still hasn't been properly described, so at the present time and until better remains are found (if ever), these claims remain questionable.