Temporal range: Late Jurassic
|An artist's illustration of Amphicoelias fragillimus|
| †Amphicoelias altus|
Amphicoelias is believed to have been the largest dinosaur ever to live, much bigger than Argentinosaurus. Being discovered in the late 1800's and with only one vertebrae ever found, early palaeontologists had little time to study the large bones because they were crumbling at a fast rate. It was twice the length of a blue whale and twice the length of sauropods like Diplodocus. With absolutely no physical evidence other than notes taken by Edward Drinker Cope, the dinosaur is purely skeptical in topics about its measurement.
Even without fossil evidence, photographic evidence left by the behemoth's discoverer, Edward Drinker Cope , has allowed paleontologists to make calculated estimates. It is believed to be 190 feet (58 m) long, and weigh 122.4 tonnes in recent estimates. This size exceed any other sauropod. It could have been the biggest reptile, sauropod and dinosaur yet. It could also be the biggest animal that ever lived, twice as long, though not as heavy, than the most massive blue whale, which was 30 meters long, and weighed 176 tonnes.