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Probable holotype of Amphicoelias altus in the closed collection of the American Museum of Natural History, a trunk vertebra (lying in a side view, far left the vertebral center, in the middle and right the neural arch including the spinous process)

Probable holotype of Amphicoelias altus in the closed collection of the American Museum of Natural History , a trunk vertebra (lying in a side view, far left the vertebral center, in the middle and right the neural arch including the spinous process)

Temporal occurrence
Upper Jurassic ( Tithonian )
152.1 to 145 million years
Dinosaur (dinosauria)
Lizard dinosaur (Saurischia)
Sauropods (Sauropoda)
Scientific name
Cope , 1877

Amphicoelias is a genus of sauropod dinosaur to which A. fragillimus, the largest known dinosaur, could have belonged.

The only fossil remnant and holotype of this type, however, was lost shortly after its discovery in the 1870s. The correctness of the contemporary descriptions of this specimen can therefore no longer be verified. If A. fragillimus' largest body measurements are correct, the weight of this dinosaur is close to that of the blue whale .

Amphicoelias altus

Cope's sketch of the vertebra of A. fragillimus

In 1877 the paleontologist Edward Drinker Cope found the remains of a sauropod, which he could not assign to any of the genera known at the time and therefore placed in the new genus Amphicoelias . Cope described the species he called Amphicoelias altus based on a few vertebrae , parts of the pelvis and thigh . He estimated the length of this animal to be around 20 meters.

Size comparison of the two species A. altus (green) and A. fragillimus (orange). The reconstruction of the silhouettes follows the blueprint of the Diplodocidae. A. fragillimus has recently been interpreted as Rebbachisauride ( Maraapunisaurus fragillimus ) and is only estimated to be about 30 m head-tail length.

Amphicoelias fragillimus

The following year, Cope claims to have discovered the vertebral arch of a new species in Colorado , which he described as Amphicoelias fragillimus . The fossil was in poor condition, but was extraordinarily large - in total it measured 2.4 meters. The find is said to have been packaged by Cope and sent by train to New York . The vertebral arch, however, never arrived there; the find is said to have crumbled during the journey. The only remains are the description and a sketch.

Comparisons with members of the Diplodocidae , a group of particularly elongated dinosaurs to which Amphicoelias is counted, suggest a putative length of 40 to 60 meters and a weight of 100 to 150 tons.

Assessing the veracity of this discovery is made difficult by the fact that the Bone Wars were taking place between the two leading paleontologists of the time, Cope and Othniel Charles Marsh - a veritable race between the two to find the most and most spectacular Brought finds to light. This dispute was also carried out through bribery, theft and sabotage. Marsh finally won "victory" - a number of spectacular discoveries by well-known dinosaurs such as Triceratops , Allosaurus , Diplodocus and Stegosaurus go to his account. While there is no evidence of Cope's fraud, and even Marsh did not doubt the find, these circumstances cast doubt on the vast, unconfirmed vortex find.

Recent studies revise the massive size estimate of Amphicoelias fragillimus . In 2018, Kenneth Carpenter estimated the total length of the animal to be 30-32 meters with a weight of over 100 tons. In 2019, Gregory S. Paul estimated the species to be 35-40 meters long.


A systematic classification of the genus Amphicoelias is difficult due to the sparse remains . The finds of the type species A. altus suggest that they are related to the Diplodocidae . Another species described, A. latus , is now considered a synonym of a Camarasaurus species.

On the basis of Cope's descriptions and sketches alone, A. fragillimus was identified as a representative of the Rebbachisauridae in 2018 and therefore placed in its own genus, Maraapunisaurus .

Web links

Commons : Amphicoelias  - collection of images, videos and audio files

Individual evidence

  1. ^ A b Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ et al. 2010, ISBN 978-0-691-13720-9 , p. 191, online .
  2. a b c Kenneth Carpenter: Maraapunisaurus fragillimus , ng (formerly Amphicoelias fragillimus ), a basal Rebbachisaurid from the Morrison Formation (Upper Jurassic) of Colorado. Geology of the Intermountain West. Vol. 5, 2018, pp. 227–244 ( PDF ).
  3. ^ Paul, Gregory S. (2019). " Determining the largest known land animal: A critical comparison of differing methods for restoring the volume and mass of extinct animals " Annals of the Carnegie Museum . 85 (4): 335-358.