List of dinosaurs of the Morrison Formation

Further information: Morrison Formation

The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rocks that is found in the western United States, which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone, and limestone, and is light gray, greenish gray, or red. Most of the fossils occur in the green siltstone beds and lower sandstones, relics of the rivers and floodplains of the Jurassic period.

Fauna comparisons

The fauna of the Morrison Formation is similar to the ones found in the coeval rocks of the Tendaguru and Lourinhã formations from Tanzania and Portugal respectively,^[1] mostly with the second. Some genera are shared between the Morrison and Lourinhã, such as Torvosaurus,^[2] Ceratosaurus,^[3] Stegosaurus, Dryosaurus,^[4] and Allosaurus.^[5] In sum, Morrison Formation has 37 valid genera of dinosaurs.

Ornithischians

The herbivorous ornithischian dinosaurs were diverse but not as common as sauropods in the Morrison. Fruitadens, previously known as the "Fruita Echinodon", was a heterodontosaurid. Stegosaurs included Hesperosaurus mjosi, Stegosaurus (S. ungulatus and S. stenops), and Alcovasaurus longispinus. Ankylosaurs were unknown in the formation until the 1990s. Two have been named: Gargoyleosaurus parkpinorum and Mymoorapelta maysi. Small neornithischians included Nanosaurus agilis, Enigmacursor mollyborthwickae, Laosaurus (L. celer and L. gracilis), Drinker nisti, Othnielia rex, and Othnielosaurus consors (the last three of which are now considered synonymous with Nanosaurus). Ornithopods were represented by Dryosaurus (D. altus and D. elderae), Uteodon aphanoecetes, which is currently known only from Dinosaur National Monument, and the larger, more common Camptosaurus dispar. All of the aforementioned ornithopod genera were early iguanodonts, the group that gave rise to the duck-billed dinosaurs.

Neornithischians

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Genus	Species	Locality	Material	Notes	Images
Anomoepus		Colorado[6]		Anomoepus from the Morrison lack the handprint impressions found associated with earlier instances of the ichnogenus in New England[6]	Camptosaurus dispar Dryosaurus altus Enigmacursor mollyborthwickae Nanosaurus agilis Uteodon aphanoecetes
Camptosaurus[7]	C. amplus[8]	Wyoming [8][9]		Now known to be based on a theropod foot[10]
	C. aphanoecetes[11]	Utah, Brushy Basin member[11]		Reclassified as Uteodon
	C. browni[12]			Junior synonym of C. dispar[13]
	C. dispar[14][15]	Colorado, Oklahoma, Utah and Wyoming[16][17][14][9]	Twenty-five to thirty disarticulated skull elements, some with associated postcrania, and approximately ten partial, articulated skeletons, all from juveniles and adults[18]	A member of Ankylopollexia. Junior synonyms include Camptosaurus browni, C. medius, and C. nanus
	C. medius[12]			Junior synonym of C. dispar[13]
	C. nanus[12]			Junior synonym of C. dispar[13]
Dinehichnus[6]		Utah, Saltwash member[6]	Multiple trackways have been discovered. The tracks run parallel to one another, indicating that the trackmaker was at least a somewhat social animal[6]	Dinehichnus are attributed to dryosaurids. The tracks preserve feet characterized by widely splayed toes that are rotated somewhat towards the midline of the trackmaker's body. Each track is accompanied by "distinct heel impressions"[6]
Drinker[7][19]	D. nisti[19]	Wyoming[9][20]	"Partial skull and postcranial skeleton."[21]	Junior synonym of Nanosaurus[22]
Dryosaurus[7]	D. altus[14]	Colorado and Wyoming, Brushy Basin member[16][23][9][24][25]	The remains of many individuals have been uncovered, with some sites containing hundreds of bones from Dryosaurus of multiple age groups[23]	A dryosaurid iguanodont. It was physically similar to Nanosaurus, although larger and with more derived teeth[24]
	D. elderae[22]	Utah, Brushy Basin member[14][25]	Two partial skeletons, one from a juvenile, and two additional fragmentary specimens	The second described species of Dryosaurus
Enigmacursor	E. mollyborthwickae	Colorado	A partial but three-dimensionally preserved skeleton[26]	A small neornithischian
Laosaurus	L. altus			Now known as Dryosaurus altus
	L. celer	Wyoming[9]		Considered dubious due to fragmentary remains
	L. consors			Now known as Othnielosaurus consors
	L. gracilis			Considered dubious due to fragmentary remains
Nanosaurus	N. agilis	Colorado, Brushy Basin member[16][27]		A small basal neornithischian known from dozens of individuals.[22] The holotype, YPM VP 1913, is a fragmentary skeleton from a juvenile[22]
Othnielia	O. rex[28]	Colorado, Brushy Basin member[16][27]	An isolated femur[28]	Considered dubious and many remains historically assigned to this taxon are now placed within Nanosaurus
Othnielosaurus[7]	O. consors	Utah and Wyoming[14][9]		Junior synonym of Nanosaurus[22]
Preprismatoolithus[29]	P. coloradensis[29]	Colorado, Salt Wash member[29]	Eggshells are present in great abundance at the so-called "Young Egg Locality" which seems to have been a dinosaur nesting ground.[29] Congeneric eggshell fossils are found at additional Colorado sites including the Fruita Paleontological Area, the Uravan Locality, and Garden Park.[29]	P. coloradensis is described by John Foster as being "of the prismatic basic type",[29] with subspherical eggs about 10 cm (3.9 in) in diameter.[30] This oospecies has been attributed to "hypsilophodontid" dinosaurs, although a lack of associated embryo material currently makes confirming the layer's identity impossible[29]
Tichosteus	T. aequifacies	Colorado[16]	Two partial dorsal centra of a juvenile
	T. lucasanus	Colorado[16]	Two partial dorsal centra
Uteodon	U. aphanoecetes[11]	Utah, Brushy Basin member[11]	An articulated postcranial skeleton	Sometimes synonymized with Camptosaurus[22]

Thyreophorans

Ankylosaurs

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Genus	Species	Locality	Material	Notes	Images
Gargoyleosaurus[7]	G. parkpinorum[31]	Wyoming[9]	Skull and partial postcranium[32]	A nodosaurid ankylosaur known from reasonably complete fossil remains. Its skull measures 29 cm (11 in) in length, and its total body length is an estimated 3 to 4 m (9.8 to 13.1 ft). It may have weighed as much as 1 t (2,200 lb)[31]	Gargoyleosaurus parkpinorum Mymoorapelta maysi
Mymoorapelta[7]	M. maysi[16]	Colorado and Utah, Brushy Basin member [16][33]	Skull fragments, portions of three skeletons, and other postcrania[34]	Both the first ankylosaur discovered in the formation and the first known North American Jurassic ankylosaur.[35] It probably weighed 500 kg (1,100 lb) in life[35]

Stegosaurs

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Genus	Species	Locality	Material	Notes	Images
Alcovasaurus	A. longispinus	Wyoming, Brushy Basin member[9][36]	A fragmentary postcranial skeleton from an adult [37]	A dacentrurine stegosaurid physically similar to Stegosaurus stenops but with much larger tail spines.[38] It is also similar to Kentrosaurus in having long dermal spikes on the caudal region.[36] The thighbone length was determined at 1082 millimeters. The longest spike was 86 centimeters long. Its point was broken and it is estimated the original length of the bone core was at 985 millimeters. In 2019, the genus Alcovasaurus was considered a junior synonym of Miragaia[39]	Alcovasaurus longispinus Hesperosaurus mjosi Stegosaurus stenops Stegosaurus ungulatus
Hesperosaurus[7]	H. mjosi[7]	Wyoming and Montana[9][40]	Multiple partial skeletons and skulls[40]	A stegosaurine stegosaurid that was slightly smaller and more primitive than Stegosaurus itself. Hesperosaurus had a broader skull and longer, lower plates. Considered by some researchers to be a species of Stegosaurus
Stegopodus[41]		Utah[41]	Stegopodus represent only a portion of the Morrison's stegosaur tracks, which are already rare and generally only preserve the animal's hind feet[41]	Stegosaur tracks which record front feet with five digits and hind feet with three weight-bearing digits.[41] The general morphology of the tracks fit scientific predictions made eight years in advance of the erection of Stegopodus[41]
Stegosaurus[7]	S. armatus[14]	Colorado, Brushy Basin[16][42]	Several caudal vertebrae and assorted fragmentary postcranial elements.[42]	S. armatus is both the first Stegosaurus species to be discovered and the original type species.[43] Its type specimen is poorly preserved, incomplete, and lacks diagnostic features.[42] It has been considered dubious, with S. stenops as the neotype species for the genus[42]
	S. stenops[14]	Colorado, Utah and Wyoming, Brushy Basin member[16][14][9][44]	Two complete skeletons with skulls, four braincases, and at least fifty partial postcrania, all from juveniles and adults[37]	The best known Stegosaurus species. It has shorter limbs and larger plates than S. ungulatus[45]
	S. sulcatus[14]	Wyoming[46]	Several postcranial elements, including a possible shoulder spike.[42]	Often considered synonymous with S. stenops,[47] but it may be distinct. Potentially had a shoulder spike, otherwise unknown in Stegosaurus, despite being present in most relatives[42]
	S. ungulatus[14]	Wyoming and Utah[9][14]	Several partial skeletons, including a partial braincase[42]	S. ungulatus had longer limbs and comparatively smaller plates than the better known S. stenops.[48] Although formerly portrayed with eight tail spikes, it is now known to have had the typical four.[49] Possibly synonymous with S. stenops[50]
	Indeterminate[51]	New Mexico & Oklahoma[51][17]

Other ornithischians

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Genus	Species	Locality	Material	Notes	Images
Anomoepus					Fruitadens haagarorum
Fruitadens[52]	F. haagarorum[52]	Colorado, Brushy Basin member[53]	A partial skull and mandible with several postcranial elements[54]	A heterodontosaurid

Sauropods

Sauropods, the giant long-necked long-tailed four-legged herbivorous dinosaurs, are among the most common and famous Morrison fossils. A few have uncertain relationships, like "Apatosaurus" minimus (possibly a basal titanosauriform) and Haplocanthosaurus. 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 Maraapunisaurus fragilimus. Smaller sauropods, such as Suuwassea emiliae from Montana, tend to be found in the northern reaches of the Morrison, near the shores of the ancient Sundance Sea, suggesting ecological niches favoring smaller body size there compared with the giants found further south.^[55]

Haplocanthosaurids

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Genus	Species	Locality	Material	Notes	Images
Haplocanthosaurus[7]	H. delfsi[16]	Colorado, Brushy Basin member[16]	Partial skeleton lacking a skull.[56]	Small haplocanthosaurs of indeterminate classification, ranging about 14 metres (46 feet) long.	Haplocanthosaurus delfsi
	H. priscus[16]	Colorado and Wyoming, Brushy Basin member[16][9]	Two skulless partial skeletons.[56]

Rebbachisaurids

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Genus	Species	Locality	Material	Notes	Images
Maraapunisaurus[57]	M. fragillimus[16]	Colorado, Brushy Basin member[16]	A single, now lost, dorsal neural arch.[57]	Large rebbachisaurid. Based on a single lost neural arch 1.5 metres (4.9 feet) tall.[57]	Lost type vertebra of Maraapunisaurus fragillimus next to Edward D. Cope.

Dicraeosaurids

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Genus	Species	Locality	Material	Notes	Images
Dyslocosaurus	D. polyonychius	Wyoming[58]	A fragmentary forelimb and partial hindlimbs.	Phylogenetic placement is uncertain.[58]
Smitanosaurus[59]	S. agilis[16][59]	Colorado, Brushy Basin member[16]	"Partial skull and cervicals."[60]	A dicraeosaurid sauropod. Originally described as "Morosaurus" agilis.[59]
Suuwassea[7]	S. emilieae	Montana, Brushy Basin member[61]	A partial skull and some postcrania.[55]	A dicraeosaurid about 15m in length.

Diplodocids

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Genus	Species	Locality	Material	Notes	Images
Amphicoelias	A. altus[16]	Colorado, Brushy Basin member[16]	2 dorsal vertebrae, femur, and a pubis.[62]	A large diplodocid about 25 metres (82 feet) in length.[63]	Amphicoelias altus Apatosaurus louisae Ardetosaurus viator Barosaurus lentus Brontosaurus excelsus Diplodocus carnegii Diplodocus hallorum Galeamopus hayi Kaatedocus siberi Supersaurus vivianae
Apatosaurus[7]	A. ajax[16]	— Colorado, Brushy Basin member[16]	A partial postcranial skeleton and posterior skull.[58]	A robust and abundantly widespread apatosaurine diplodocid reaching lengths of up to 25 metres (82 feet).[64] "A." minimus likely belongs to a separate genus.
	A. louisae[14]	Colorado and Utah, Brushy Basin member [16][14]	Four partial specimens, one of them including a skull.[58] Three of the specimens are from DNM, one is a mid cervical from Como Bluff.[58]
	"A." minimus	Wyoming[9]	"Sacrum and pelvis."[60]
Ardetosaurus	A. viator	Howe-Stephens Quarry, Wyoming.	Holotype specimen MAB011899, a partial skeleton containing the sacrum, ribs, a coracoid and parts of the vertebral column and hindlegs.	A diplodocine sauropod from the younger layers of the Morrison Formation, originally considered a specimen of Diplodocus.[65]
Atlantosaurus	A. montanus	Colorado, Brushy Basin member[28]	A partial sacrum that cannot be distinguished from Camarasaurus or Apatosaurus.[66]	A dubious neosauropod.[66]
Barosaurus[7]	B. lentus[14]	South Dakota and Utah[67][14]	2 partial postcranial skeletons, with possibly more specimens assignable.[58]	A diplodocid about 24 metres (79 feet) in length, similar in appearance to Diplodocus. It was the rarest sauropod in the Morrison Formation.[68]
	B. sp.	Wyoming, Utah and Oklahoma
Brontosaurus	B. excelsus	Wyoming, Brushy Basin member[58][69]	Two postcranial skeletons.[58]	Previously considered a species of Apatosaurus as per Riggs (1903).
	B. parvus	Utah and Wyoming, Salt Wash and Brushy Basin members	Three headless skeletons.[58]	Originally called Elosaurus.
	B. yahnahpin[58]	Wyoming, Brushy Basin member	A partial postcranial skeleton.[58]	An apatosaurine diplodocid slightly more primitive than Apatosaurus. Formerly placed in separate genus Eobrontosaurus.
Diplodocus[7]	D. carnegii[14]	Wyoming, Brushy Basin Member[9][70]	Known from two skulls, five partial skeletons that lack skulls and manus, and hundreds of isolated postcranial remains.[71]	A large diplodocid reaching lengths of up to 28 metres (92 feet). It was one of the most abundant sauropods in the area.[72]
	D. hallorum	New Mexico, Wyoming and Utah, Brushy Basin and Salt Wash members[51]	At least 4 partial postcranial skeletons[58]	Once classified as Seismosaurus.[73][74][75][76]
	D. lacustris[16]	Colorado, Brushy Basin member[16]	Known from teeth and skull remains, the latter now referred to Camarasaurus.[58] Teeth cannot be referred beyond Flagellicaudata.[58]
	D. longus[14]	Colorado, Brushy Basin member[16]	Several caudal vertebrae.[77]
Galeamopus	G. hayi	Wyoming, Brushy Basin member[9][58]	Known from a partial skeleton and braincase.[71]
	G. pabsti	Colorado and Wyoming, Brushy Basin member	A skull and partial postcranial skeleton, another individual known from partial skull.[58]
Kaatedocus[78]	K. siberi	Wyoming, Salt Wash member[78]	Skull and cervical vertebrae.[78]
Parabrontopodus
Saurophaganax[7][17]	S. maximus[17]	Oklahoma, Brushy Basin member[17][79][80]	Several partial postcranial skeletons.[81]	Historically considered to be an allosaurid close to or a species of Allosaurus, but re-evaluated as a dubious, chimeric genus of saurischian, likely a diplodocid sauropod.[81]
Supersaurus[7][16]	S. vivianae[16]	Colorado and Wyoming, Brushy Basin member	Known from several partial postcranial skeletons.[62]	A large diplodocid about 33–34 m (108–112 ft) in length

Macronarians

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Genus	Species	Locality	Material	Notes	Images
Brachiosaurus[7]	B. altithorax[7]	Colorado, Brushy Basin and Salt Wash members[16]	Several partial skeletons and a partial skull.	A large brachiosaurid about 18–22 m (59–72 ft) long.	Brachiosaurus altithorax Camarasaurus supremus
Brontopodus
Camarasaurus[7]	C. annae[14]	Utah, Brushy Basin member[14]	A dorsal vertebra.	Camarasaurs reached an adult size of about 18 metres (59 feet) in length.[82] C. annae junior synonym of C. lentus. C. lewisi was originally described as Cathetosarus lewisi and was later sunk into Camarasaurus, until being considered valid once again in 2013.
	C. grandis[16]	Colorado, Montana and Wyoming[16][83][9]	"At least 6 partial skeletons including 2 skulls, hundreds of postcranial elements."[56]
	C. lentus[14]	Utah and Wyoming[14][9]	"5 skeletons with skulls, hundreds of postcranial elements"[56]
	C. lewisi[16]	Colorado, Brushy Basin member[16]	A nearly complete postcranial skeleton.[56]
	C. supremus[16]	Colorado and Oklahoma(?), Brushy Basin member[16][84]	At least 4 partial skeletons including partial skulls. Many possible postcranial remains from Oklahoma.[84]
	Indeterminate.	Oklahoma, South Dakota and Texas[17][67][85]
Dystrophaeus	D. viaemalae[86]	Utah, Tidwell member[86]	Multiple vertebrae, teeth and incomplete forelimb material.[86]	Previously recovered as a diplodocid, now recovered as a macronarian[86] Type material fragmentary, but recent rediscovery of type locality has discovered more material.[87]

Theropods

Theropod dinosaurs, the carnivorous dinosaurs, came in several different types. The less derived types, the ceratosaurs and megalosaurids, included Ceratosaurus nasicornis, C. dentisulcatus, C. magnicornis, and the megalosaur Torvosaurus tanneri (including Edmarka rex). Allosaurids included the common Allosaurus fragilis (including Epanterias amplexus), A. jimmadseni and A. anax (previously referred to Saurophaganax maximus).

Indeterminate theropod remains have been recovered in Utah, with indeterminate ceratosaur remains formerly considered referable to Elaphrosaurus recovered in Colorado. Indeterminate theropod tracks have been recovered from both Utah and Arizona.^[88]

Allosauroidea

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Genus	Species	Locality	Material	Notes	Images
Allosaurus[7]	A. fragilis[14]	Colorado, New Mexico, Oklahoma, South Dakota, Utah and Wyoming, Brushy Basin member[16][51][17][67][9][89]	"At least [three] complete skulls, many partial skulls and skull elements, many partial and complete skeletons representing at least 60 individuals."[90] It was the most common large carnivore in the area.[91][92][93]		Allosaurus fragilis
	A. jimmadseni[94]	Wyoming and Utah, Brushy Basin and Salt Wash members[89][93]	At least 15 specimens, including several skulls.
	A. anax[81]	Oklahoma, Kenton Member[81]	Postorbital and partial postcranial material
Antrodemus	A. valens	Colorado[80]	Half of a proximal caudal centrum	Considered dubious due to fragmentary remains.[95]
Creosaurus	C. atrox	Wyoming, Brushy Basin member[96]	A fragmentary skull and assorted postcrania.[96]	Considered a junior synonym of Allosaurus.
Epanterias	E. amplexus	Colorado, Brushy Basin member[97]	Several fragmentary postcranial elements of 2 individuals,[98] possible additional remains known from Wyoming.[99]	Considered dubious due to fragmentary remains.[97]
Labrosaurus	L. lucaris	Wyoming, Brushy Basin member[80]	A fragmentary skull and several postcranial elements.[95][80]	Junior synonym of A. fragilis.[80]
	L. ferox	Wyoming, Brushy Basin member[80]	A partial skull, dentaries, and fragmentary postcrania.[100][80]	Known from one specimen with several pathologies. Today considered a junior synonym of A. fragilis.[80]

Ceratosaurs

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Genus	Species	Locality	Material	Notes	Images
Ceratosaurus[7]	C. dentisulcatus[14]	Utah[14]	"Partial skull, vertebrae, [and] limb elements."[101]	Large ceratosaurs grew to lengths of about 6–7 meters (20–23 ft) in length with large nasal horns on their snouts as well as two smaller horns above the eyes.	Ceratosaurus nasicornis Fosterovenator churei
	C. magnicornis[16]	Colorado[16]	"Skull [and] assorted postcrania."[101]
	C. nasicornis[16]	Colorado and Utah, Brushy Basin member[16][14]	Remains of "5 individuals, including [a] nearly complete adult skeleton and subadult skeleton."[101]
	Indeterminate.[9]	Wyoming[9]
Ceratosauria[7]	Indeterminate.[16]	Colorado[16]		Previously referred to Elaphrosaurus,[102][103][104] these remains are probably not referable to that genus and are best considered indeterminate beyond Ceratosauria.[105]
Elaphrosaurus	Intermediate[16]	Colorado[16]		Now thought to be indeterminate beyond Ceratosauria.
Fosterovenator[106]	F. churei[106]	Wyoming[106]	Tibia, astragalus, fibula.[106]	A fragmentary theropod which may be a ceratosaurid.

Coelurosaurs

Coelurosaurs, the group of theropods most closely related to and including birds, included Coelurus fragilis, Ornitholestes hermanni, Tanycolagreus topwilsoni, the possible troodontid Koparion douglassi, the definite troodontid Hesperornithoides, and the early tyrannosauroid Stokesosaurus clevelandi.

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Genus	Species	Locality	Material	Notes	Images
Coelurus[7]	C. fragilis[14]	Utah and Wyoming, Brushy Basin member[14][9]	A partial skeleton in several syntypes and several fragmentary referred specimens.[107]	A basal coelurosaurian about 2.3 metres (7.5 feet) long.	Coelurus fragilis Hesperornithoides miessleri Koparion douglassi Ornitholestes hermanni Stokesosaurus clevelandi Tanycolagreus topwilsoni
	Indeterminate.[16]	Colorado[16]
Hesperornithoides[108]	H. miessleri	Wyoming		An early troodontid.
Koparion[7]	K. douglassi[14]	Utah[14]		A small theropod thought to be one of the oldest known troodontids.
Palaeopteryx[16]	P. thomsoni[16]	Colorado, Brushy Basin member[16]	A distal radius
Ornitholestes[7]	O. hermanni[9]	Wyoming[9]	"Skull and associated postcranial skeleton."[107]	A small basal coelurosaurian about 2 metres (6.6 feet) long.
Stokesosaurus[7]	S. clevelandi[14]	Utah[14]	"Illium, associated elements and pelvic cranial material. [sic]"[109]	A possible early tyrannosauroid about 4 metres (13 feet) in length.
Tanycolagreus[7]	T. topwilsoni	Wyoming and Utah		A basal coelurosaurian about 3.4 metres (11 feet) long, similar in appearance to Coelurus.

Megalosauroids

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Genus	Species	Locality	Material	Notes	Images
Edmarka[7]	E. rex[9]	Wyoming[9]		Possibly a junior synonym of Torvosaurus tanneri.
Marshosaurus[7]	M. bicentesimus[14]	Colorado and Utah[16][14]	Partial skeleton, including part of a skull.[110]	A medium-sized piatnitzkysaurid megalosauroid about 6 metres (20 feet) in length.	Marshosaurus bicentesimus
Torvosaurus[7]	T. tanneri[14]	Colorado, Utah and Wyoming, Brushy Basin member[16][14][9]	"Partial skeletons of at least [three] individuals."[111]	A large, robust megalosaurid reaching lengths of up to 9 m (30 ft).[112] One of the largest carnivores of the formation.	Torvosaurus tanneri

Eggs

Dinosaur eggs have been found in Utah.^[14]

Tracks

Ornithopods

Morrison ornithopod trace fossils are represented by three toed tracks which are generally small.^[6] The toes of Morrison ornithopod tracks are usually more widely splayed than the theropod tracks preserved in the formation.^[6]

Stegosaurs

Stegosaur tracks were first recognized in 1996 from a hindprint-only trackway discovered at the Cleveland-Lloyd quarry, which is located near Price, Utah.^[41] 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.^[41] Unlike the first, this trackway preserved traces of the forefeet. Fossil remains indicate that stegosaurs have five digits on the forefeet and three weight-bearing digits on the hind feet.^[41] From this, scientists were able to successfully predict the appearance of stegosaur tracks in 1990, six years in advance of the first actual discovery of Morrison stegosaur tracks.^[41] Since the erection of Stegopodus, more trackways have been found, however none have preserved traces of the front feet, and stegosaur traces remain rare.^[41]

Theropods

Indeterminate theropod tracks have been recovered from both Utah and Arizona.^[88]