Құрып кеткен динозаврлар туысы Ағатаума

Extinct genus of dinosaurs

Agathaumas (/æ//ɡ//ə/'/θ//ɔː//m//ə//s/; "great wonder") is a dubious genus of a large ceratopsid dinosaur that lived in Wyoming during the Late Cretaceous (late Maastrichtian stage, 66 million years ago). The name comes from αγαν 'much' and θαυμα 'wonder'. It is estimated to have been long and weighed , and was seen as the largest land animal known at the time of its discovery.

The holotype remains of Agathaumas were first found in 1872 in southwestern Wyoming. They were discovered by Fielding Bradford Meek and Henry Martyn Bannister while they were looking for fossil shells in the Lance Formation near the Black Butte and Bitter Creek. Meek and Bannister were employed by Ferdinand Vandeveer Hayden's Geological Survey of the Territories and notified paleontologist Edward Drinker Cope of the find. Cope himself searched the ridge near Black Butte and re discovered Meek's site, finding huge bones protruding from the rocks near a coal vein. The bones were preserved in sand and clay sediments, packed with fossil sticks and leaves, indicating a heavily forested habitat. Cope later (in 1873) described the skeleton as "the wreck of one of the princes among giants." Cope and his team eventually recovered complete hip bones, sacral vertebrae, and several ribs from the animal. Later in 1872, Cope published a description and name for the animal, Agathaumas sylvestris, or "marvelous forest dweller," in reference to its great size and the environment revealed in the same rocks as its bones. The name Agathaumas has been cited as an example of Cope's excitement with this discovery, which he considered, at the time, as the largest known land animal that had ever lived. Several years later, with the discovery of the giant sauropod dinosaurs of the Morrison Formation, it became clear to him that British forms such as Cetiosaurus and Pelorosaurus were land animals.

Cope originally did not know to what group Agathaumas belonged, though he noted that some of the remains were similar to the British reptile Cetiosaurus In 1883, with his description of the skull of Edmontosaurus (Diclonius), Cope also suggested that his taxa Agathaumas, Monoclonius, and Dysganus could be Hadrosaurids. Cope did not assign Agathaumas into the group now recognized as Ceratopsia until later in 1889, when Cope recognized that his genera Monoclonius and Polyonax were related due to Marsh's description of Triceratops fossils. Marsh had already named a group for the horned dinosaurs, Ceratopsidae, but Cope did not recognize this family name as he believed Ceratops could not be distinguished from other taxa; Cope erected a new name, Agathaumidae. After reassessment by John Bell Hatcher, Richard Swann Lull, and Nelda Wright in the 1900s and 1930s, all of the members of Agathaumidae were found to be dubious, and the family name Ceratopsidae was preferred over Agathaumidae.