Temporal range: Late Jurassic
|An artist's illustration of Amphicoelias fragillimus|
| †Amphicoelias altus|
Amphicoelias is a enormous sauropod dinosaur from the Late Jurassic of North America. It May have been the largest dinosaur ever to live, possibly much bigger than Argentinosaurus with a length of 40 to 60 meters. 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 58-60 meters (190 feet) long, and weigh 122.4 tonnes (though several recent estimates of weight have placed it at around 60 tonnes, due to a possibly flawed system of extrapolation). This size exceeds 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 as, though not as heavy, than the most massive blue whale, which was 29.9 meters long, and weighed 173 tonnes.