|Barosaurus, small and large. Also, sauropods: it takes a special kind|
of organism to make an individual the length of two buses 'small.'
Meaning: slow heavy reptile
Time: Late Jurassic, c 150 million years ago
Place: South Dakota, Utah, Colorado
Size: about 25 metres (82 feet) long and 13 tonnes (14.3 tons) typically; some (presumably) very old individuals appear to have reached sizes of approximately 50 metres (164 feet) long and 105 tonnes (116 tons)
Type of Dinosaur: diplodocine diplodocid (slender-built whip-tailed long-necked dinosaur)
Barosaurus is often forgotten amongst the Morrison Formation sauropods, losing out to more famous and familiar contemporaries Diplodocus, Brontosaurus, Apatosaurus, Camarasaurus, and Brachiosaurus. The impressive rearing specimen at the American Museum of Natural History is probably Barosaurus's most iconic - which isn't bad at all; many would say the AMNH display is the most incredible fossil mount in the world. Other than that, though, Barosaurus just doesn't have the presence some of its neighbour sauropods do.
However, there's the 'little' matter of BYU 9024 to consider... this specimen, a neck vertebra, comes from the Dry Mesa Quarry in Colorado and, at 138 centimetres (54.3 inches) long, is the largest vertebra known from any animal, ever. Initially identified as coming from a Supersaurus specimen, the SV-POWsketeers Mike Taylor and Matt Wedel have recently proposed that this bone is from Barosaurus - it matches the existing specimens of Barosaurus perfectly, except in size. This bone would come from an animal roughly twice as long as the AMNH mount, and probably around eight times as massive. In the picture above, the animal in the foreground is an AMNH-style, 25-metre Barosaurus; the looming monstrosity in the background is a BYU-style, 50-metre individual... and I'm not actually sure that I made it big enough.