 Based on collection data, the specimen was determined to have come from the Late Jurassic Morrison Formation, in the youngest layers, separate from those that held the "Camarasaurus" fossils also described by Cope.Cope listed multiple features to separate "Amphicoelias" and "A. altus" from their relatives.Unlike in "Camarasaurus", the of dorsals did not have an , where the front end has a ball that fits into the socket of the preceding vertebra.