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Amphicoelias

Amphicoelias fragillimus (pronounced AM-fi-koil-i-as fra-GIL-i-mus, and meaning "very fragile double cavities") may be the major dinosaur ever discovered. If it truly existed, it would be the longest vertebrate by a substantial margin, and it would have a mass that rivals the heaviest animal known, the blue whale. However, because the only fossil evidence for its existence is lost, proof survives only in drawings, and doubt has been expressed about their veracity.

The Bone Wars The validity of the discover is complicated by its discovery in the midst of the Bone Wars, an infamous period in the history of paleontology, when the two pre-eminent paleontologists of the time, Othniel Charles Marsh and Edward Drinker Cope, were rival to see who could find the most, and most sensational, new species. This competition was marred by bribery, accusations of robbery, spying, politics, and strong personal attacks.

Marsh was charming the bone war. He discovered a total of 86 new species during their decades-long rivalry, due in part to his detection of the Como Bluff site, near Medicine Bow, Wyoming, one of the richest sources of fossils ever uncovered. Cope only discovered 56; many of the fossils he unearthed were of species that had already been named, or were of unsure origin, so he was not credited with their discovery. As a result, Marsh's name is attached to many of the most famous dinosaurs, such as Triceratops, Allosaurus, Diplodocus, and Stegosaurus, while even Cope's most well-known discoveries, such as Dimetrodon (not actually a dinosaur), Camarasaurus, Coelophysis, and Monoclonius are more difficult to understand. So while there is no evidence of fabrication, the circumstances surrounding Amphicoelias do raise some doubt about the authenticity of the find.

The crumbling giant

The dorsal vertebra of a. fragillimus deliberates 2.4 m (7.8 ft) long. Comparing it with known species of diplodocid (a family of very long and slender sauropods), various estimates of the animal's length and mass include:

A length of 56–62 m (185–200 ft.), and a weight of 125–170 t (140–185 tons)
A length of 50 m (165 ft.), and a weight of 120–150 t (130–165 tons).
A length of 45 m (150 ft.), and a weight of 100–150 t (110–165 tons).
A length of 45–60 m (150–195 ft.).
By comparison the blue whale, which is the highest living creature, only reaches 30–33 m (100–110 ft.) in length, and the longest animal for which solid evidence exists, Supersaurus, is only predictable to be about 40 m (130 ft.) long.

While A. fragillimus was relatively thin, its huge size still makes it very massive. The heaviest blue whale on record weighed about 175 t (195 tons), which is just slightly larger than the higher range of estimates for Amphicoelias. For the sake of comparison, the heaviest dinosaur that we have good proof for, the Argentinosaurus, only weighed 80–100 t (90–100 tons), although if the size estimates can be validated, it would still be lighter than Bruhathkayosaurus, which is predictable to weight 175–220 t (190–240 tons) (based on a poor description of a partial fossil).

Classification

Edward Drinker Cope described his locate an 1878 issue of the American Naturalist, and named it A. fragillimus. He secret it as a diplodocid, specifically a new species in the genus Amphicoelias. McIntosh as simply a large specimen of A. latus reclassified the species in 1998.

The genus Amphicoelias is badly known. The first named species in the type, A. latus (holotype specimen AMHD 5764), was discovered by Cope the year prior to, in 1877. But while a partial skeleton only represents it, there are enough diagnostic characteristics to provisionally define the genus.