Amphicoelias fragillimus

If existed, this animal was the longest and one of the biggest dinosaurs ever to walked the earth. This diplodocoid animal was maybe up to 60 metres long(!) and was described by edward drinker cope in 1878. Two species are known, A. fragillimus and A. altus. The animal was a herbivore and the only material found of A. fragillimus were some massive vertebra and limb bones.These fragile fossils(hence its species name fragillimus) were so fragile that they didnt make the way to the museum as the terrain they were transported was very stony. At the time the bones arrived ,they were reduced to dust.