List of dinosaurs of the Morrison Formation

The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock that is found in the western United States, which has been the most fertile source of dinosaur fossils in North America.

Most of the fossils occur in the green siltstone beds and lower sandstones, relics of the rivers and floodplains of the Jurassic period.

Larger but similar-looking dryosaurids were represented by two species of Dryosaurus (D. altus and D. elderae) and the camptosaurid Uteodon aphanoecetes, which is currently known only from Dinosaur National Monument.

[24] D. elderae[22] Utah, Brushy Basin member[14][25] A large dryosaurid iguanodont up to 2.4 m (7.9 feet) long and 114 kg (251 lbs) in weight.

Junior synonym of Nanosaurus agilis[22] Preprismatoolithus[28] P. coloradensis[28] Colorado, Salt Wash member[28] Eggshell present in great abundance at the so-called "Young Egg Locality" which seems to have been a dinosaur nesting ground.

[28] Congeneric eggshell fossils are found at additional Colorado sites including the Fruita Paleontological Area, the Uravan Locality and Garden Park.

[28] P. coloradensis is described by John Foster as being "of the prismatic basic type,"[28] with subspherical eggs about 10 cm (4 inches) in diameter.

[29] This oospecies has been attributed to "hypsilophodontid" dinosaurs, although a lack of associated embryo material currently makes confirming the egg-layer's identity impossible.

Uteodon U. aphanoecetes[11] Utah, Brushy Basin member[11] Gargoyleosaurus[7] G. parkpinorum[30] Wyoming[9] "Skull [and] partial postcranium.

[30] Mymoorapelta[7] M. maysi[16] Colorado and Utah, Brushy Basin member [16][32] "Skull fragments, portions of [three] skeletons, [and] other postcrania.

In 2019, the genus Alcovasaurus was considered a junior synonym of Miragaia[38] Hesperosaurus[7] H. mjosi[7] Wyoming and Montana[9][39] Multiple partial skeletons and skulls[39] A stegosaurine stegosaurid that was slightly smaller and more primitive than Stegosaurus itself.

[40] The general morphology of the tracks fit scientific predictions made eight years in advance of the erection of Stegopodus.

[41] S. stenops[14] Colorado, Utah and Wyoming, Brushy Basin member[16][14][9][43] "[Two] complete skeletons with skulls, [four] braincases, at least [fifty] partial postcrania, juvenile to adult.

Sauropods, the giant long-necked long-tailed four-legged herbivorous dinosaurs, are among the most common and famous Morrison fossils.

Sauropods including Haplocanthosaurus priscus, H. delfsi, and the diplodocid Brontosaurus yahnahpin appeared in the early stages of the Morrison.

The middle stages were dominated by familiar forms such as the giraffe-like Brachiosaurus altithorax, which were uncommon, but related camarasaurids, like Camarasaurus supremus, C. grandis, C. lentus, and Cathetosaurus/Camarasaurus lewisi, were very common.

Also common were long, low diplodocids, like Apatosaurus ajax, A. louisae, Brontosaurus excelsus, B. parvus, Barosaurus lentus, Diplodocus longus, D. carnegii, Galeamopus and Dyslocosaurus polyonychius.

By the late Morrison, gigantic diplodocids (or similar species) had appeared, including Diplodocus hallorum (formerly Seismosaurus), Supersaurus vivianae, Amphicoelias altus, and M. fragilimus.

[56] Dyslocosaurus D. polyonychius Wyoming[57] Smitanosaurus[58] S. agilis[16][58] Colorado, Brushy Basin member[16] "Partial skull and cervicals.

[71] D. hallorum New Mexico, Wyoming and Utah, Brushy Basin and Salt Wash members[50] At least 4 partial postcranial skeletons[57] Once classified as Seismosaurus.

[72][73][74][75] D. lacustris[16] Colorado, Brushy Basin member[16] Known from teeth and skull remains, the latter now referred to Camarasaurus.

Brontopodus Camarasaurus[7] C. annae[14] Utah, Brushy Basin member[14] Camarasaurs reached an adult size of about 18 m (60 ft) in length.

C. grandis[16] Colorado, Montana and Wyoming[16][82][9] "At least 6 partial skeletons including 2 skulls, hundreds of postcranial elements.

[90][91][92] A. jimmadseni[93] Wyoming and Utah, Brushy Basin and Salt Wash members[88][92] A. anax[80] Antrodemus A. valens Colorado[79] Considered dubious due to fragmentary remains.

Epanterias E. amplexus Colorado, Brushy Basin member[96] Considered dubious due to fragmentary remains.

Coelurus[7] C. fragilis[14] Utah and Wyoming, Brushy Basin member[14][9] A partial skeleton in several syntypes and several fragmentary referred specimens.

Palaeopteryx[16] P. thomsoni[16] Colorado, Brushy Basin member[16] Ornitholestes[7] O. hermanni[9] Wyoming[9] "Skull and associated postcranial skeleton.

Tanycolagreus[7] T. topwilsoni Wyoming and Utah A basal coelurosaurian about 3.4 m (11.3 ft) long, similar in appearance to Coelurus.

[6] Stegosaur tracks were first recognized in 1996 from a hindprint-only trackway discovered at the Cleveland-Lloyd quarry, which is located near Price, Utah.

[40] Two years later, a new ichnogenus called Stegopodus was erected for another set of stegosaur tracks which were found near Arches National Park, also in Utah.