Amphicoelias
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Amphicoelias is a genus of herbivorous sauropod dinosaur that lived approximately 150 million years ago during the Tithonian of what is now Colorado, United States. Amphicoelias was moderately sized a
Amphicoelias Holotype Vertebra
E.D. Cope's original sketch of Amphicoelias altus as an "amphibious lizard", c. 1897
Three skeletons informally assigned to "A. brontodiplodocus" in 2010, now labelled as diplodocids in Lee Kong Chian Natural History Museum, Singapore
Restoration of A. altus
Maraapunisaurus
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Maraapunisaurus is a genus of sauropod dinosaur from the Late Jurassic Morrison Formation of western North America. It contains one species, Maraapunisaurus fragillimus, which was originally named Amp
Amphicoelias
…lengths–the longest of any known dinosaur and sauropod–were largely ignored. In 2018, Kenneth Carpenter renamed Amphicoelias fragillimus as the new genus Maraapunisaurus, and reclassified it from Diplodocidae to Rebbachisauridae. In 1877, a number of fossils were discovered by Oramel William Lucas in rock outcrops in…
Comparison of Maraapunisaurus (left) with the rebbachisaurids Rebbachisaurus (center) and Histriasaurus (right).
Neural spine of Maraapunisaurus as drawn by E.D. Cope with parts labeled. The key rebbachisaurid features are the spinopostzygapophyseal laminae that extends dorsomedially from the postzygapophyses to join and form the postspinal lamina, and the pneumatic neural spine and arch. Other rebbachisaurid features include the rather simple ("attenuated") structure of the neural spine and the respective inclinations of the centrodiapophyseal lamina and the postzygodiapophyseal laminae.
Illustration of M. fragillimus fossils, with an alligator femur (A) for scale, drawn in 1884
Edward Drinker Cope was the only paleontologist to study M. fragillimus before its only known specimen disappeared