Dinosaurs of the Morrison Formation - AbsoluteAstronomy.com

The Morrison Formation is a distinctive sequence of Late Jurassic

Jurassic

The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

sedimentary rock

Sedimentary rock

Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....

that is found in the western United States, which has been the most fertile source of dinosaur

Dinosaur

Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

fossils in North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. It is composed of mudstone

Mudstone

Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...

, sandstone

Sandstone

Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...

, siltstone

Siltstone

Siltstone is a sedimentary rock which has a grain size in the silt range, finer than sandstone and coarser than claystones.- Description :As its name implies, it is primarily composed of silt sized particles, defined as grains 1/16 - 1/256 mm or 4 to 8 on the Krumbein phi scale...

and limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

and is light grey, greenish gray, or red. Most of the fossil

Fossil

Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

s occur in the green siltstone beds and lower sandstones, relics of the rivers and floodplains of the Jurassic

Jurassic

period.

Ornithischians

The herbivorous ornithischian dinosaurs were diverse but not as common as sauropods in the Morrison. Unclassified members include the "Fruita Echinodon
Echinodon
Echinodon meaning "hedgehog tooth" in reference to the spines on its teeth , occasionally known as Saurechinodon, is a genus of small European dinosaur of the early Cretaceous Period , 140 million years ago.-Discovery and species:The type specimen was discovered by Samuel Beckles in the Purbeck...

", a possible heterodontosaurid

Heterodontosauridae

Heterodontosauridae is a family of early ornithischian dinosaurs that were likely among the most basal members of the group...

, and the dubious Tichosteus lucasanus
Tichosteus
Tichosteus is a genus of herbivorous dinosaur from the Late Jurassic. It is known only from vertebrae recovered from Kimmeridgian rocks in the Morrison Formation, Colorado....

and T. aequifacies. Plate-backed stegosaurids

Stegosauridae

Stegosauridae is a family of stegosauria, large thyreophorans. They lived longer than other Stegosaurs; while all Huayangosauridae and most of basal stegosaurs died out in Tithonian - Kimmeridgian, stegosauridae survived till Middle Cretaceous. They are usually characterized by triangular plates on...

included Hesperosaurus mjosi
Hesperosaurus
Hesperosaurus was a herbivorous dinosaur from the Kimmeridgian to Tithonian epochs of the Jurassic period , whose fossils are found in the state of Wyoming in the United States of America...

, Hypsirophus discursus, Stegosaurus armatus
Stegosaurus
Stegosaurus is a genus of armored stegosaurid dinosaur. They lived during the Late Jurassic period , some 155 to 150 million years ago in what is now western North America. In 2006, a specimen of Stegosaurus was announced from Portugal, showing that they were present in Europe as well...

(?including S. ungulatus), S. stenops, and "S." longispinus. Armored dinosaurs

Ankylosauria

Ankylosauria is a group of herbivorous dinosaurs of the order Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. They are first known to have appeared in the early Jurassic Period of...

that weren't stegosaurs were unknown in the formation until the 1990s. Two have been named: Gargoyleosaurus parkpinorum
Gargoyleosaurus
Gargoyleosaurus is one of the earliest ankylosaurs known from reasonably complete fossil remains. Its skull measures in length, and its total body length is an estimated . It may have weighed as much as...

and Mymoorapelta maysi
Mymoorapelta
Mymoorapelta is an ankylosaur from the Late Jurassic Morrison Formation of western Colorado. The taxon is known from portions of a disarticulated skull, parts of three different skeletons and other postcranial remains...

. Ornithopods, bipedal herbivores, came in several types. Small "hypsilophodonts" included Drinker nisti, Laosaurus celer, "L." gracilis, Nanosaurus agilis
Nanosaurus
Nanosaurus is the name given to a genus of dinosaur from the Late Jurassic. Described by Othniel Charles Marsh in 1877, it is a poorly-known ornithischian of uncertain affinities. Its fossils are known from the Morrison Formation of Colorado and possibly Wyoming...

, Othnielia rex
Othnielia
Othnielia is a genus of ornithischian dinosaur, named after its original describer, Professor Othniel Charles Marsh, an American paleontologist of the 19th century...

, and Othnielosaurus consors
Othnielosaurus
Othnielosaurus is a genus of ornithischian dinosaur that lived about 155 to 148 million years ago, during the Late Jurassic-age Morrison Formation of the western United States. It is named in honor of famed paleontologist Othniel Charles Marsh, and was formerly assigned to the genus...

. Larger but similar-looking dryosaurids

Dryosauridae

Dryosaurids were primitive iguanodonts. They are known from Middle Jurassic to Early Cretaceous rocks of Africa, Europe, and North America.-Phylogeny:...

were represented by Dryosaurus altus
Dryosaurus
Dryosaurus is a genus of an ornithopod dinosaur that lived in the Late Jurassic period. It was an iguanodont . Fossils have been found in the western United States, and were first discovered in the late 19th century...

and the camptosaurid Camptosaurus
Camptosaurus
Camptosaurus is a genus of plant-eating, beaked ornithischian dinosaurs of the Late Jurassic period of western North America. The name means 'flexible lizard', ....

aphanoecetes, which is currently known only from Dinosaur National Monument. Still larger was the more common Camptosaurus dispar
Camptosaurus
Camptosaurus is a genus of plant-eating, beaked ornithischian dinosaurs of the Late Jurassic period of western North America. The name means 'flexible lizard', ....

, probably including Brachyrophus altarkansanus and Symphyrophus musculosus. Dryosaurids and camptosaurids were early iguanodont

Iguanodont

Iguanodonts were herbivorous dinosaurs that lived from the mid-Jurassic to Late Cretaceous. Some members include Camptosaurus, Callovosaurus, Iguanodon, Ouranosaurus, and the hadrosaurids or "duck-billed dinosaurs". Iguanodonts were one of the first groups of dinosaurs to be found...

s, a group that would later spawn the duck-billed dinosaurs.

Ornithopods

Genus	Species	State	Member	Material	Notes
Anomoepus Anomoepus Anomoepus gracillimus is the name assigned to fossil footprints first reported from Early Jurassic beds of the Connecticut River Valley, Massachusetts, USA in 1802....		CO			Morrison Anomoepus lack the handprint impressions found associated with earlier instances of the ichnogenus in New England.
Camptonotus Camptonotus Camptonotus is a genus of leaf-rolling crickets. It includes the following species:Camptonotus affinis Rehn, 1903Camptonotus americanus Camptonotus australis Rehn, 1907Camptonotus carolinensis...	C. dispar				The original name for Camptosaurus Camptosaurus Camptosaurus is a genus of plant-eating, beaked ornithischian dinosaurs of the Late Jurassic period of western North America. The name means 'flexible lizard', .... , which was preoccupied by a cricket.
Camptosaurus Camptosaurus Camptosaurus is a genus of plant-eating, beaked ornithischian dinosaurs of the Late Jurassic period of western North America. The name means 'flexible lizard', ....	C. amplus	WY			A species named for a large foot found at Como Bluff Como Bluff Como Bluff is a long ridge extending east-west, located between the towns of Rock River and Medicine Bow, Wyoming. The ridge is an anticline, formed as a result of compressional geological folding. Three geological formations, the Sundance, the Morrison, and the Cloverly Formations, containing... .
	C. aphanoecetes	UT	Brushy Basin		Reclassified as Uteodon Uteodon Uteodon is a genus of herbivorous iguanodontian dinosaur. It is a basal iguanodontian which lived during the upper Jurassic period in what is now Uintah County, Utah. It is known from the middle of the Brushy Basin Member, Morrison Formation. This genus was named by Andrew T. McDonald in 2011 and... .
	C. browni				Junior synonym of C. dispar.
	?C. depressus	WY		"Illia and vertebrae."	The ?C. depressus remains may be from non-Morrison strata.
	C. dispar	CO OK UT WY		"[Twenty-five to thirty] disarticulated skull elements, some with associated postcrania, approximately [ten] partial, articulated skeletons, juvenile to adult."
	C. medius				Junior synonym of C. dispar. Lack of fusion in the neural arches of the type specimen's vertebrae indicate the specimens were from a juvenile.
	C. nanus				Junior synonym of C. dispar. Lack of fusion in the neural arches of the type specimen's vertebrae indicate the specimens were from a juvenile.
Dinehichnus Dinehichnus Dinehichnus is an ichnogenus found in the Morrison Formation that is attributed to dryosaurid dinosaurs. The trackways are present in Saltwash Member outcrops at Boundary Butte in southernmost Utah. Dinehichnus trackways are frequently found in groups, traveling parallel to one another. From this...		UT	Saltwash	Multiple Dinehichnus trackways have been discovered. The tracks run parallel to one another, indicating that the trackmaker was at least somewhat of a social animal.	Dinehichnus are attributed to dryosaurids. The tracks preserve feet characterized by widely splayed toes and that are rotated somewhat toward the midline of the trackmaker's body. Each track is accompanied by "distinct ... heel impressions".
Drinker Drinker Drinker was a genus of hypsilophodont dinosaur from the late Jurassic period of North America. Although based on good remains, it remains obscure due to a lack of post-naming publications.-Description:...	D. nisti	WY		"Partial skull and postcranial skeleton."	A basal hypsilophodont Hypsilophodont Hypsilophodonts were small ornithopod dinosaurs, regarded as fast, herbivorous bipeds on the order of 1–2 meters long . They are known from Asia, Australia, Europe, New Zealand, North America, and South America, from rocks of Middle Jurassic to late Cretaceous age... about 2 m long, slightly smaller than Othnielosaurus Othnielosaurus Othnielosaurus is a genus of ornithischian dinosaur that lived about 155 to 148 million years ago, during the Late Jurassic-age Morrison Formation of the western United States. It is named in honor of famed paleontologist Othniel Charles Marsh, and was formerly assigned to the genus... . It is distinguished from other Morrison Ornithopods by the complexity of its tooth denticles.
Dryosaurus Dryosaurus Dryosaurus is a genus of an ornithopod dinosaur that lived in the Late Jurassic period. It was an iguanodont . Fossils have been found in the western United States, and were first discovered in the late 19th century...	D. altus	CO UT WY	Brushy Basin	The remains of many individuals have been uncovered, with some sites containing hundreds of bones from Dryosaurus of multiple age groups.	A large dryosaurid Dryosauridae Dryosaurids were primitive iguanodonts. They are known from Middle Jurassic to Early Cretaceous rocks of Africa, Europe, and North America.-Phylogeny:... iguanodont Iguanodont Iguanodonts were herbivorous dinosaurs that lived from the mid-Jurassic to Late Cretaceous. Some members include Camptosaurus, Callovosaurus, Iguanodon, Ouranosaurus, and the hadrosaurids or "duck-billed dinosaurs". Iguanodonts were one of the first groups of dinosaurs to be found... up to 2.4 m (7.9 feet) long and 114 kg (251 lbs) in weight. It was physically similar to Othnielosaurus Othnielosaurus Othnielosaurus is a genus of ornithischian dinosaur that lived about 155 to 148 million years ago, during the Late Jurassic-age Morrison Formation of the western United States. It is named in honor of famed paleontologist Othniel Charles Marsh, and was formerly assigned to the genus... , although larger and with more derived teeth.
"Laosaurus Laosaurus Laosaurus is a genus of hypsilophodont dinosaur. The type species is Laosaurus celer, first described by O.C. Marsh in 1878 from remains from the Oxfordian-Tithonian-age Upper Jurassic Morrison Formation of Wyoming. The validity of this genus is doubtful because it is based on fragmentary fossils... "	L. altus				Now known as Dryosaurus altus
	L. celer	WY			Considered dubious Nomen dubium In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application... due to fragmentary remains.
	L. consors
	"L. gracilis"				Considered dubious Nomen dubium In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application... due to fragmentary remains.
Nanosaurus Nanosaurus Nanosaurus is the name given to a genus of dinosaur from the Late Jurassic. Described by Othniel Charles Marsh in 1877, it is a poorly-known ornithischian of uncertain affinities. Its fossils are known from the Morrison Formation of Colorado and possibly Wyoming...	N. agilis	CO WY			A small ornithopod, possibly a hypsilophodont Hypsilophodont Hypsilophodonts were small ornithopod dinosaurs, regarded as fast, herbivorous bipeds on the order of 1–2 meters long . They are known from Asia, Australia, Europe, New Zealand, North America, and South America, from rocks of Middle Jurassic to late Cretaceous age...
Othnielia Othnielia Othnielia is a genus of ornithischian dinosaur, named after its original describer, Professor Othniel Charles Marsh, an American paleontologist of the 19th century...	O. rex	CO UT WY		"[Two] partial skeletons, postcranial elements, teeth."	A small hypsilophodont Hypsilophodont Hypsilophodonts were small ornithopod dinosaurs, regarded as fast, herbivorous bipeds on the order of 1–2 meters long . They are known from Asia, Australia, Europe, New Zealand, North America, and South America, from rocks of Middle Jurassic to late Cretaceous age... 2 m in length.
Othnielosaurus Othnielosaurus Othnielosaurus is a genus of ornithischian dinosaur that lived about 155 to 148 million years ago, during the Late Jurassic-age Morrison Formation of the western United States. It is named in honor of famed paleontologist Othniel Charles Marsh, and was formerly assigned to the genus...	O. consors				A basal hypsilophodont Hypsilophodont Hypsilophodonts were small ornithopod dinosaurs, regarded as fast, herbivorous bipeds on the order of 1–2 meters long . They are known from Asia, Australia, Europe, New Zealand, North America, and South America, from rocks of Middle Jurassic to late Cretaceous age... about 2 m long.
Preprismatoolithus Preprismatoolithus Preprismatoolithus is a Late Jurassic oogenus. The species P. coloradensis is described by John Foster as being "of the prismatic basic type," with subspherical eggs about 10 cm in diameter...	P. coloradensis	CO	Salt Wash	Eggshell present in great abundance at the so-called "Young Egg Locality" which seems to have been a dinosaur nesting ground. Congeneric eggshell fossils are found at additional Colorado sites including the Fruita Paleontological Area, the Uravan Locality and Garden Park.	P. coloradensis is described by John Foster as being "of the prismatic basic type," with subspherical eggs about 10cm (4 inches) in diameter. This oospecies has been attributed to "hypsilophodontid" dinosaurs, although a lack of associated embryo material currently makes confirming the egg-layer's identity impossible.
Tichosteus Tichosteus Tichosteus is a genus of herbivorous dinosaur from the Late Jurassic. It is known only from vertebrae recovered from Kimmeridgian rocks in the Morrison Formation, Colorado....	T. aequifacies	CO		"Vertebrae."
	T. lucasanus	CO	"Vertebra."
Uteodon Uteodon Uteodon is a genus of herbivorous iguanodontian dinosaur. It is a basal iguanodontian which lived during the upper Jurassic period in what is now Uintah County, Utah. It is known from the middle of the Brushy Basin Member, Morrison Formation. This genus was named by Andrew T. McDonald in 2011 and...	U. aphanoecetes	UT	Brushy Basin

Thyreophorans

Genus	Species	State	Member	Material	Notes
Anomoepus Anomoepus Anomoepus gracillimus is the name assigned to fossil footprints first reported from Early Jurassic beds of the Connecticut River Valley, Massachusetts, USA in 1802....
Gargoyleosaurus Gargoyleosaurus Gargoyleosaurus is one of the earliest ankylosaurs known from reasonably complete fossil remains. Its skull measures in length, and its total body length is an estimated . It may have weighed as much as...	G. parkpini	WY			An early ankylosaur Ankylosauridae An ankylosaurid is a member of the Ankylosauridae family of armored dinosaurs that evolved 125 million years ago and became extinct 65 million years ago during the Cretaceous-Tertiary extinction event... similar to Mymoorapelta Mymoorapelta Mymoorapelta is an ankylosaur from the Late Jurassic Morrison Formation of western Colorado. The taxon is known from portions of a disarticulated skull, parts of three different skeletons and other postcranial remains... in appearance and lifestyle, although differing in osteological details like the length of vertebral centra.
	G. parkpinorum	WY	"Skull [and] partial postcranium."
Hesperosaurus Hesperosaurus Hesperosaurus was a herbivorous dinosaur from the Kimmeridgian to Tithonian epochs of the Jurassic period , whose fossils are found in the state of Wyoming in the United States of America...	H. mjosi	WY	"Complete skeleton with skull, subadult."	Known only from a single specimen.	A stegosaurid Stegosauria Known colloquially as stegosaurs, the Stegosauria are a group of herbivorous dinosaurs of the Jurassic and Early Cretaceous Periods, being found mostly in the Northern Hemisphere, predominantly in what is now North America and China.... that was slightly smaller and more primitive than Stegosaurus Stegosaurus Stegosaurus is a genus of armored stegosaurid dinosaur. They lived during the Late Jurassic period , some 155 to 150 million years ago in what is now western North America. In 2006, a specimen of Stegosaurus was announced from Portugal, showing that they were present in Europe as well... itself. H. mjosi had a broader skull and longer, lower plates Osteoderm Osteoderms are bony deposits forming scales, plates or other structures in the dermal layers of the skin. Osteoderms are found in many groups of extant and extinct reptiles, including lizards, various groups of dinosaurs , crocodilians, phytosaurs, aetosaurs, placodonts, and hupehsuchians... .
Hypsirhophus	H. discurus	CO		"[Two] dorsal vertebrae, caudal neural arch fragment."
Mymoorapelta Mymoorapelta Mymoorapelta is an ankylosaur from the Late Jurassic Morrison Formation of western Colorado. The taxon is known from portions of a disarticulated skull, parts of three different skeletons and other postcranial remains...	M. maysi	CO	Brushy Basin	"Skull fragments, portions of [three] skeletons, [and] other postcrania."	Both the first ankylosaur discovered in the formation and the first known North American Jurassic ankylosaur. It probably weighed 500 kg (1,102 lbs) in life.
Stegopodus Stegopodus Stegopodus was a new ichnogenus erected in 1998 for the second set of stegosaur tracks from the Morrison Formation. The tracks were found near Arches National Park, also in Utah. Unlike the first, this trackway preserved traces of the forefeet. Fossil remains indicate that stegosaurs have five...		UT		Stegopodus represent only a portion of the Morrison's stegosaur tracks, which are already rare and generally only preserve the animal's hind feet.	Stegosaur tracks which record front feet with five digits and hind feet with three weight-bearing digits. The general morphology of the tracks fit scientific predictions made eight years in advance of the erection of Stegopodus.
Stegosaurus Stegosaurus Stegosaurus is a genus of armored stegosaurid dinosaur. They lived during the Late Jurassic period , some 155 to 150 million years ago in what is now western North America. In 2006, a specimen of Stegosaurus was announced from Portugal, showing that they were present in Europe as well...	S. affinis	UT		"Pubis."
	S. armatus	CO UT WY		"[Two] partial skeletons, [two] braincases, at least [thirty] fragmentary postcrania, adult."	S. armatus is both the first Stegosaurus to be discovered and the type species. Its type specimen is poorly preserved, incomplete, and has never been fully prepared. Consequently it is not possible to tell which, if any, of the subsequently erected Stegosaurus species are synonymous with it, and it is likely one or more of them are.
	S. stenops	CO UT WY		"[Two] complete skeletons with skulls, [four] braincases, at least [fifty] partial postcrania, juvenile to adult."	The best known Stegosaurus species, it has shorter limbs and larger plates than S. ungulatus.
	?S. longispinus	UT WY		"Fragmentary postcranial skeleton, adult."	Physically similar to S. stenops but with much larger tail spines. May or may not be a separate species.
	S. ungulatus	UT WY			S. ungulatus had longer limbs and comparatively smaller plates than the better known S. stenops. Although formerly portrayed with eight tail spikes, it is now known to have had the typical four. Possibly synonymous with S. armatus.
	Indeterminate.	NM OK

Misc

Genus	Species	State	Member	Notes
Anomoepus Anomoepus Anomoepus gracillimus is the name assigned to fossil footprints first reported from Early Jurassic beds of the Connecticut River Valley, Massachusetts, USA in 1802....
Echinodon Echinodon Echinodon meaning "hedgehog tooth" in reference to the spines on its teeth , occasionally known as Saurechinodon, is a genus of small European dinosaur of the early Cretaceous Period , 140 million years ago.-Discovery and species:The type specimen was discovered by Samuel Beckles in the Purbeck...	Indeterminate.			Later determined to be a new, unique genus which was named Fruitadens Fruitadens Fruitadens is a genus of heterodontosaurid dinosaur. The name means "Fruita tooth", in reference to Fruita, Colorado , where its fossils were first found. It is known from partial skulls and skeletons from at least four individuals of differing biological ages, found in Tithonian rocks of the... in 2009 2009 in paleontology -Anomalocaridids:-Arachnids:-Insects:-Cephalopods:Three new species of extinct Octopoda discovered in 2009. The species - Keuppia hyperbolaris, Keuppia levante, and Styletoctopus annae - lived about 95 million years ago, and bear a strong resemblance to modern octopuses, suggesting that the... .
Fruitadens Fruitadens Fruitadens is a genus of heterodontosaurid dinosaur. The name means "Fruita tooth", in reference to Fruita, Colorado , where its fossils were first found. It is known from partial skulls and skeletons from at least four individuals of differing biological ages, found in Tithonian rocks of the...	F. haagarorum	CO	Brushy Basin

Sauropods

Sauropoda

Sauropoda , or the sauropods , are an infraorder of saurischian dinosaurs. They had long necks, long tails, small heads , and thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land...

, 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

Apatosaurus

Apatosaurus , also known by the popular but scientifically deprecated synonym Brontosaurus, is a genus of sauropod dinosaur that lived from about 154 to 150 million years ago, during the Jurassic Period . It was one of the largest land animals that ever existed, with an average length of and a...

(possibly an early titanosaur

Titanosaur

Titanosaurs were a diverse group of sauropod dinosaurs, which included Saltasaurus and Isisaurus. It includes some of the heaviest creatures ever to walk the earth, such as Argentinosaurus and Paralititan — which some believe have weighed up to 100 tonnes...

) and Haplocanthosaurus
Haplocanthosaurus
Haplocanthosaurus is a genus of sauropod dinosaur. Two species, H. delfsi and H. priscus, are known from incomplete fossil skeletons. It lived during the late Jurassic period , 155 to 152 million years ago. The type species is H. priscus, and the referred species H...

. Sauropods including Haplocanthosaurus priscus
Haplocanthosaurus
Haplocanthosaurus is a genus of sauropod dinosaur. Two species, H. delfsi and H. priscus, are known from incomplete fossil skeletons. It lived during the late Jurassic period , 155 to 152 million years ago. The type species is H. priscus, and the referred species H...

, H. delfsi, and the diplodocids Dystrophaeus
Dystrophaeus
Dystrophaeus is the name given to an extinct genus of dinosaur from the early Kimmeridgian stage of the Late Jurassic that existed around 155.7 Ma. It was perhaps a diplodocoid sauropod. Its fossils were found in the Morrison Formation of Utah....

and Eobrontosaurus
Eobrontosaurus
Eobrontosaurus is the name given to a genus of dinosaur from the Late Jurassic of North America. It was a sauropod probably closely related to Apatosaurus. It is known from a single site from the lower Morrison Formation, dating to about 154 million years ago. It grew up to long.The type species, E...

appeared in the early stages of the Morrison. The middle stages were dominated by familiar forms such as the Giraffe

Giraffe

The giraffe is an African even-toed ungulate mammal, the tallest of all extant land-living animal species, and the largest ruminant...

-like Brachiosaurus altithorax
Brachiosaurus
Brachiosaurus is a genus of sauropod dinosaur from the Jurassic Morrison Formation of North America. It was first described by Elmer S. Riggs in 1903 from fossils found in the Grand River Canyon of western Colorado, in the United States. Riggs named the dinosaur Brachiosaurus altithorax,...

, which were uncommon, but related camarasaurids, like Camarasaurus supremus
Camarasaurus
Camarasaurus meaning 'chambered lizard', referring to the hollow chambers in its vertebrae was a genus of quadrupedal, herbivorous dinosaurs. It was the most common of the giant sauropods to be found in North America...

, C. grandis, C. lentus, and C. lewisi, were very common. Also common were long, low diplodocids, like Apatosaurus ajax
Apatosaurus
Apatosaurus , also known by the popular but scientifically deprecated synonym Brontosaurus, is a genus of sauropod dinosaur that lived from about 154 to 150 million years ago, during the Jurassic Period . It was one of the largest land animals that ever existed, with an average length of and a...

, A. excelsus (formerly "Brontosaurus"), A. louisae, A. parvus, Atlantosaurus montanus
Atlantosaurus
Atlantosaurus is a dubious genus of sauropod dinosaur. The type specimen, found by Arthur Lakes in the Morrison Formation of Colorado, USA, was described by Othniel Charles Marsh, a Professor of Paleontology at Yale University , in 1877 as "Titanosaurus" montanus...

, Barosaurus lentus
Barosaurus
Barosaurus ; Greek barys/βαρυς meaning 'heavy' and saurus/σαυρος meaning 'lizard', 'heavy lizard') was a giant, long-tailed, long-necked, plant-eating dinosaur closely related to the more familiar Diplodocus...

, Diplodocus longus
Diplodocus
Diplodocus , or )is a genus of diplodocid sauropod dinosaur whose fossils were first discovered in 1877 by S. W. Williston. The generic name, coined by Othniel Charles Marsh in 1878, is a Neo-Latin term derived from Greek "double" and "beam", in reference to its double-beamed chevron bones...

, D. carnegii, "D." hayi, "D." lacustris, Dyslocosaurus polyonychius
Dyslocosaurus
Dyslocosaurus is the name given in 1992 to a genus of sauropod dinosaur, possibly from the Late Jurassic Period. Its fossils were found in North America....

.

By the late Morrison, gigantic diplodocids (or likely diplodocids) had appeared, including Diplodocus hallorum (formerly Seismosaurus), Supersaurus vivianae
Supersaurus
Supersaurus is a genus of diplodocid sauropod dinosaur discovered by Vivian Jones of Delta, Colorado, in the Upper Jurassic Morrison Formation of Colorado in 1972. The fossil remains came from the Brushy Basin Member of the formation, dating to about 153 million years ago...

, Amphicoelias altus
Amphicoelias
Amphicoelias is a genus of herbivorous sauropod dinosaur that includes what may be the largest dinosaur ever discovered, A. fragillimus. Based on surviving descriptions of a single fossil bone, A. fragillimus may have been the longest known vertebrate at in length, and may have had a mass of up...

, and the largest of all, A. fragilimus. Smaller sauropods, such as Suuwassea emiliae
Suuwassea
Suuwassea is a genus of diplodocoid sauropod dinosaur found in the Upper Jurassic strata of the Morrison Formation, located in southern Carbon County, Montana, USA. The fossil remains were recovered in a series of expeditions during a period spanning the years 1999 and 2000, described by J.D....

from Montana

Montana

Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...

, tend to be found in the northern reaches of the Morrison, near the shores of the ancient Sundance Sea

Sundance Sea

The Sundance Sea was an epeiric sea that existed in North America during the mid to late Jurassic Period of the Mesozoic Era. It was an arm of what is now the Arctic Ocean, and extended through what is now western Canada into the central western United States...

, suggesting ecological niches favoring smaller body size there compared with the giants found further south.

Diplodicoids

Genus	Species	State	Material	Notes
Amphicoelias Amphicoelias Amphicoelias is a genus of herbivorous sauropod dinosaur that includes what may be the largest dinosaur ever discovered, A. fragillimus. Based on surviving descriptions of a single fossil bone, A. fragillimus may have been the longest known vertebrate at in length, and may have had a mass of up...	A. altus	CO	"Partial skull and skeleton, dorsal vertebrae, pubis, femur."	Large diplodocids Diplodocoidea Diplodocoidea was a superfamily of sauropod dinosaurs, which included some of the longest animals of all time, including slender giants like Supersaurus, Diplodocus, Apatosaurus, and Amphicoelias... about 25 m (82 ft) in length. A. fragillimus may have obtained a length of up to 60 m (190 ft) in length based on a single neural arch 1.5 m (5 ft) tall.
	A. brontodiplodocus	WY
	A. fragillimus
Atlantosaurus Atlantosaurus Atlantosaurus is a dubious genus of sauropod dinosaur. The type specimen, found by Arthur Lakes in the Morrison Formation of Colorado, USA, was described by Othniel Charles Marsh, a Professor of Paleontology at Yale University , in 1877 as "Titanosaurus" montanus...	A. montanus
Barosaurus Barosaurus Barosaurus ; Greek barys/βαρυς meaning 'heavy' and saurus/σαυρος meaning 'lizard', 'heavy lizard') was a giant, long-tailed, long-necked, plant-eating dinosaur closely related to the more familiar Diplodocus...	B. lentus	SD UT	"[Five] partial skeletons without skulls [and] isolated limb elements."	A diplodocid Diplodocoidea Diplodocoidea was a superfamily of sauropod dinosaurs, which included some of the longest animals of all time, including slender giants like Supersaurus, Diplodocus, Apatosaurus, and Amphicoelias... about 24 m (79 ft) in length, similar in appearance to Diplodocus Diplodocus Diplodocus , or )is a genus of diplodocid sauropod dinosaur whose fossils were first discovered in 1877 by S. W. Williston. The generic name, coined by Othniel Charles Marsh in 1878, is a Neo-Latin term derived from Greek "double" and "beam", in reference to its double-beamed chevron bones... .
	Indeterminate.	CO
Diplodocus Diplodocus Diplodocus , or )is a genus of diplodocid sauropod dinosaur whose fossils were first discovered in 1877 by S. W. Williston. The generic name, coined by Othniel Charles Marsh in 1878, is a Neo-Latin term derived from Greek "double" and "beam", in reference to its double-beamed chevron bones...	D. carnegii	NM UT WY	Known from two skulls, five partial skeletons that lack skulls and manus, and hundreds of isolated postcranial remains.	Large diplodocids Diplodocoidea Diplodocoidea was a superfamily of sauropod dinosaurs, which included some of the longest animals of all time, including slender giants like Supersaurus, Diplodocus, Apatosaurus, and Amphicoelias... reaching lengths of up to 28 m (92 ft).
	D. hallorum
	D. hayi	WY	Known from a partial skeleton and braincase.
	D. lacustris	CO	Known from a dentary with teeth.
	D. longus	CO UT	Known from two skulls and a series of tail vertebrae.
	Indeterminate.	MT
Dystrophaeus Dystrophaeus Dystrophaeus is the name given to an extinct genus of dinosaur from the early Kimmeridgian stage of the Late Jurassic that existed around 155.7 Ma. It was perhaps a diplodocoid sauropod. Its fossils were found in the Morrison Formation of Utah....
Eobrontosaurus Eobrontosaurus Eobrontosaurus is the name given to a genus of dinosaur from the Late Jurassic of North America. It was a sauropod probably closely related to Apatosaurus. It is known from a single site from the lower Morrison Formation, dating to about 154 million years ago. It grew up to long.The type species, E...	E. yahnahpin	WY		An apatosaurine diplodocid Diplodocoidea Diplodocoidea was a superfamily of sauropod dinosaurs, which included some of the longest animals of all time, including slender giants like Supersaurus, Diplodocus, Apatosaurus, and Amphicoelias... slightly more primitive than Apatosaurus Apatosaurus Apatosaurus , also known by the popular but scientifically deprecated synonym Brontosaurus, is a genus of sauropod dinosaur that lived from about 154 to 150 million years ago, during the Jurassic Period . It was one of the largest land animals that ever existed, with an average length of and a... .
Haplocanthosaurus Haplocanthosaurus Haplocanthosaurus is a genus of sauropod dinosaur. Two species, H. delfsi and H. priscus, are known from incomplete fossil skeletons. It lived during the late Jurassic period , 155 to 152 million years ago. The type species is H. priscus, and the referred species H...	H. delfsi	CO	Partial skeleton lacking a skull.	Small haplocanthosaurs of indeterminate classification, ranging about 14 m (46 ft) long.
	H. priscus	CO WY	Two skulless partial skeletons.
Parabrontopodus Parabrontopodus Parabrontopodus is an ichnogenus of dinosaur footprint.-References:...
Seismosaurus	S. halli	NM	"Pelvis [and] partial vertebral column."
Titanosaurus Titanosaurus Titanosaurus is a genus of sauropod dinosaur, first described by Lydekker in 1877. It is known from the Maastrichtian Lameta Formation of India...	T. montanus	CO	"Sacral centra."

Apatosaurines

Genus	Species	State	Material	Notes
Apatosaurus Apatosaurus Apatosaurus , also known by the popular but scientifically deprecated synonym Brontosaurus, is a genus of sauropod dinosaur that lived from about 154 to 150 million years ago, during the Jurassic Period . It was one of the largest land animals that ever existed, with an average length of and a...	A. ajax	CO	Two partial skeletons and a braincase.	Robust apatosaurine diplodocids Diplodocoidea Diplodocoidea was a superfamily of sauropod dinosaurs, which included some of the longest animals of all time, including slender giants like Supersaurus, Diplodocus, Apatosaurus, and Amphicoelias... reaching lengths of up to 25 m (82 ft).
	A. excelsus	CO OK WY	Six partial skeletons lacking preserved skulls and hundreds of isolated postcranial elements.
	A. louisae	UT	Two mostly complete skeletons, but only one preserving a skull. An additional partial skeleton and isolated limb elements have been found.
	A. minimus	WY	"Sacrum [and] pelvis."
	A. parvus
	Indeterminate.	NM SD
Brontosaurus	B. amplus	CO
Dystylosaurus	D. edwini	CO	"Dorsal vertebra."
Supersaurus Supersaurus Supersaurus is a genus of diplodocid sauropod dinosaur discovered by Vivian Jones of Delta, Colorado, in the Upper Jurassic Morrison Formation of Colorado in 1972. The fossil remains came from the Brushy Basin Member of the formation, dating to about 153 million years ago...	S. vivianae	CO	Known from some neck vertebrae, shoulder elements, and ischium and some proximal tail vertebrae.	A large diplodocid Diplodocoidea Diplodocoidea was a superfamily of sauropod dinosaurs, which included some of the longest animals of all time, including slender giants like Supersaurus, Diplodocus, Apatosaurus, and Amphicoelias... about 38 m (125 ft) in length.
Suuwassea Suuwassea Suuwassea is a genus of diplodocoid sauropod dinosaur found in the Upper Jurassic strata of the Morrison Formation, located in southern Carbon County, Montana, USA. The fossil remains were recovered in a series of expeditions during a period spanning the years 1999 and 2000, described by J.D....	S. emilieae			A small diplodocid Diplodocoidea Diplodocoidea was a superfamily of sauropod dinosaurs, which included some of the longest animals of all time, including slender giants like Supersaurus, Diplodocus, Apatosaurus, and Amphicoelias... about 15m in length.
Ultrasaurus Ultrasaurus Ultrasaurus is a genus of sauropod dinosaur discovered by Haang Mook Kim in South Korea. However, the name was first used unofficially in 1979 by Jim Jensen to describe a set of giant dinosaur bones he discovered in the United States...	U. macintoshi	CO
Ultrasauros	U. macintoshi	CO

Macronarians

Genus	Species	State	Material	Notes
Brachiosaurus Brachiosaurus Brachiosaurus is a genus of sauropod dinosaur from the Jurassic Morrison Formation of North America. It was first described by Elmer S. Riggs in 1903 from fossils found in the Grand River Canyon of western Colorado, in the United States. Riggs named the dinosaur Brachiosaurus altithorax,...	Brachiosaurus cf. altithorax	CO (no cf.) UT	"Partial skeletons from [two] individuals."	A large brachiosaurid Brachiosauridae Brachiosauridae are a family of dinosaurs, whose members are known as brachiosaurids. They were herbivorous quadrupeds with longer forelegs than hind legs - the name derives from the Greek for arm lizard - and long necks... about 18 m (60 ft) long.
Brontopodus Brontopodus Brontopodus is an ichnogenus of dinosaur footprint. The footprint has diplodocid form, but four toes when almost every diplodocid has no more than three. This leaves Dyslocosaurus as the only known genus capable of producing the footprints....
Camarasaurus Camarasaurus Camarasaurus meaning 'chambered lizard', referring to the hollow chambers in its vertebrae was a genus of quadrupedal, herbivorous dinosaurs. It was the most common of the giant sauropods to be found in North America...	C. supremus	CO NM WY	"At least 5 partial skeletons including braincase and jaws."	Camarasaurs reached an adult size of about 18 m (60 ft) in length. A Camarasaurus pelvis from the Cleveland-Lloyd Quarry shows evidence of gouging that has been attributed to Allosaurus Allosaurus Allosaurus is a genus of large theropod dinosaur that lived 155 to 150 million years ago during the late Jurassic period . The name Allosaurus means "different lizard". It is derived from the Greek /allos and /sauros... . A juvenile specimen was recovered from Dinosaur National Monument in Utah.
	C. lentus	UT WY	"5 skeletons with skulls, hundreds of postcranial elements"
	C. annae	UT
	C. grandis	CO MT WY	"At least 6 partial skeletons including 2 skulls, hundreds of postcranial elements."
	C. lewisi	CO	"Nearly complete postcranial skeleton."
	Indeterminate.	OK SD TX
Cathetosaurus				Junior synonym of Camarasaurus Camarasaurus Camarasaurus meaning 'chambered lizard', referring to the hollow chambers in its vertebrae was a genus of quadrupedal, herbivorous dinosaurs. It was the most common of the giant sauropods to be found in North America... .
Morosaurus	M. agilis	CO	"Partial skull and cervicals."	Junior synonym of Camarasaurus Camarasaurus Camarasaurus meaning 'chambered lizard', referring to the hollow chambers in its vertebrae was a genus of quadrupedal, herbivorous dinosaurs. It was the most common of the giant sauropods to be found in North America... .
Uintasaurus				Junior synonym of Camarasaurus Camarasaurus Camarasaurus meaning 'chambered lizard', referring to the hollow chambers in its vertebrae was a genus of quadrupedal, herbivorous dinosaurs. It was the most common of the giant sauropods to be found in North America... .

Theropods

Theropod dinosaur

Dinosaur

s, the carnivorous dinosaurs, came in several different types. The less derived

Derived

In phylogenetics, a derived trait is a trait that is present in an organism, but was absent in the last common ancestor of the group being considered. This may also refer to structures that are not present in an organism, but were present in its ancestors, i.e. traits that have undergone secondary...

types, the ceratosaurs

Ceratosauria

Ceratosaurs are members of a group of theropod dinosaurs defined as all theropods sharing a more recent common ancestry with Ceratosaurus than with birds. There is presently no universally agreed upon listing of species or diagnostic characters of Ceratosauria, though they were less derived...

and megalosaurids, included Ceratosaurus nasicornis
Ceratosaurus
Ceratosaurus meaning "horned lizard", in reference to the horn on its nose , was a large predatory theropod dinosaur from the Late Jurassic Period , found in the Morrison Formation of North America, in Tanzania and Portugal...

, C. dentisulcatus, C. magnicornis, Elaphrosaurus
Elaphrosaurus
Elaphrosaurus is a genus of theropod dinosaur from the Kimmeridgian stage of the Late Jurassic of Tanzania. Elaphrosaurus was probably a ceratosaur about 6 meters long. Suggestions that it is a late surviving coelophysoid have been entertained but are generally dismissed. It was first...

sp., and the megalosaur Torvosaurus tanneri
Torvosaurus
Torvosaurus is a genus of large theropod dinosaur that lived during the Late Jurassic period...

(?including Edmarka rex
Edmarka
Edmarka is a genus of dinosaur from the Late Jurassic of North America. The name honors scientist Bill Edmark. It was a theropod closely related to Torvosaurus, and may, in fact, be a junior synonym of that genus. Its fossils, including a partial skeleton, were found at Como Bluff, Wyoming.The...

). Allosaurids included the common Allosaurus fragilis
Allosaurus
Allosaurus is a genus of large theropod dinosaur that lived 155 to 150 million years ago during the late Jurassic period . The name Allosaurus means "different lizard". It is derived from the Greek /allos and /sauros...

(including Epanterias amplexus
Epanterias
Epanterias is a dubious genus of theropod dinosaur from the Kimmeridgian-Tithonian-age Upper Jurassic upper Morrison Formation of Garden Park, Colorado. It was described by Edward Drinker Cope in 1878. The type species is Epanterias amplexus. This genus is based on what is now AMNH 5767, parts of...

), A. new species, Antrodemus valens
Antrodemus
Antrodemus is a dubious genus of theropod dinosaur from the Kimmeridgian-Tithonian-age Upper Jurassic Morrison Formation of Middle Park, Colorado...

, and giant Saurophaganax maximus
Saurophaganax
Saurophaganax is a genus of allosaurid dinosaur from the Morrison Formation of Late Jurassic Oklahoma . Some paleontologists consider it to be a species of Allosaurus...

.

Indeterminate theropod remains have been recovered in Utah. Indeterminate theropod tracks have been recovered from both Utah and Arizona.

Carnosaurs

Genus	Species	State	Material	Notes
Allosaurus Allosaurus Allosaurus is a genus of large theropod dinosaur that lived 155 to 150 million years ago during the late Jurassic period . The name Allosaurus means "different lizard". It is derived from the Greek /allos and /sauros...	A. fragilis	CO NM OK SD UT WY	"At least [three] complete skulls, many partial skulls and skull elements, many partial and complete skeletons representing at least 60 individuals."
	"A. jimmadseni"	UT
Antrodemus Antrodemus Antrodemus is a dubious genus of theropod dinosaur from the Kimmeridgian-Tithonian-age Upper Jurassic Morrison Formation of Middle Park, Colorado...	A. valens
Epanterias Epanterias Epanterias is a dubious genus of theropod dinosaur from the Kimmeridgian-Tithonian-age Upper Jurassic upper Morrison Formation of Garden Park, Colorado. It was described by Edward Drinker Cope in 1878. The type species is Epanterias amplexus. This genus is based on what is now AMNH 5767, parts of...	E. amplexus			An allosaurid about 12.1 m (40 ft) in length, similar in appearance to Allosaurus Allosaurus Allosaurus is a genus of large theropod dinosaur that lived 155 to 150 million years ago during the late Jurassic period . The name Allosaurus means "different lizard". It is derived from the Greek /allos and /sauros... .
Labrosaurus	L. ferox	CO
	L. lucaris	WY
	L. sulcatus	WY
Laelaps Laelaps The name Laelaps is a name attributed to the following:Laelaps was a Greek mythological dog who never failed to catch what he was hunting.Laelaps is a genus of mites which are ectoparasites of rodents...	L. trihedrodon	CO	Although the type specimen included a partial dentary, all material except for a collection of five damaged partial tooth crowns (AMNH 5780) has been lost.	AMNH 5780 has many features in common with Allosaurus and is probably referrable to that genus. However some of the Allosaurus-like characters of the tooth are primitive to theropods as a whole and may have been present in the less studied or poorly preserved Morrison theropod species. Consequently the synonymization of L. trihedrodon with Allosaurus is tentative, despite its high likelihood.
Saurophaganax Saurophaganax Saurophaganax is a genus of allosaurid dinosaur from the Morrison Formation of Late Jurassic Oklahoma . Some paleontologists consider it to be a species of Allosaurus...	S. maximus	OK	"Isolated cranial and postcranial elements."	A large allosaurid reaching lengths of up to 12.5 m (41 ft). The largest carnivore known from the formation.

Ceratosaurs

Genus	Species	State	Material	Notes
Ceratosaurus Ceratosaurus Ceratosaurus meaning "horned lizard", in reference to the horn on its nose , was a large predatory theropod dinosaur from the Late Jurassic Period , found in the Morrison Formation of North America, in Tanzania and Portugal...	C. dentisulcatus	UT	"Partial skull, vertebrae, [and] limb elements."	Large ceratosaurs Ceratosauria Ceratosaurs are members of a group of theropod dinosaurs defined as all theropods sharing a more recent common ancestry with Ceratosaurus than with birds. There is presently no universally agreed upon listing of species or diagnostic characters of Ceratosauria, though they were less derived... about 6 m (20 ft) in length with large nasal horns on their snouts as well as two smaller horns above the eyes.
	C. magnicornis	CO	"Skull [and] assorted postcrania."
	C. nasicornis	CO UT	Remains of "5 individuals, including [a] nearly complete adult skeleton and subadult skeleton."
	Indeterminate.	WY
Elaphrosaurus Elaphrosaurus Elaphrosaurus is a genus of theropod dinosaur from the Kimmeridgian stage of the Late Jurassic of Tanzania. Elaphrosaurus was probably a ceratosaur about 6 meters long. Suggestions that it is a late surviving coelophysoid have been entertained but are generally dismissed. It was first...	Indeterminate.	CO		A medium-sized ceratosaur Ceratosauria Ceratosaurs are members of a group of theropod dinosaurs defined as all theropods sharing a more recent common ancestry with Ceratosaurus than with birds. There is presently no universally agreed upon listing of species or diagnostic characters of Ceratosauria, though they were less derived... about 6 m (20 ft) in length.
Labrosaurus	L. sulcatus		"Tooth."

Coelurosaurs

Coelurosauria

Coelurosauria is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. In the past, it was used to refer to all small theropods, although this classification has been abolished...

, more derived types more closely related to birds, included Coelurus fragilis
Coelurus
Coelurus is a genus of coelurosaur dinosaur from the Late Jurassic period . The name means "hollow tail", referring to its hollow tail vertebrae...

, Ornitholestes hermanni
Ornitholestes
Ornitholestes was a small theropod dinosaur of the late Jurassic of Western Laurasia . To date, it is known only from a single partial skeleton, and badly crushed skull found at the Bone Cabin Quarry near Medicine Bow, Wyoming, in 1900...

, Tanycolagreus topwilsoni
Tanycolagreus
Tanycolagreus is a genus of coelurid theropod from the Late Jurassic of North America. The holotype is a partial skeleton recovered from the Bone Cabin Quarry West locality, Albany County, Wyoming, from the Morrison Formation...

, the possible troodontid

Troodontidae

Troodontidae is a family of bird-like theropod dinosaurs. During most of the 20th century, troodontid fossils were few and scrappy and they have therefore been allied, at various times, with many dinosaurian lineages...

Koparion douglassi
Koparion
Koparion is a genus of small theropod dinosaur, known only from isolated teeth. Koparion douglassi, the type specimen, was described by Chure in 1994, who believed it to be a coelurosaurian theropod, possibly one of the oldest known troodontids. Found in Utah, the fossil is from the late Jurassic...

, and the definite troodontid WDC DML 001

WDC DML 001

WDC DML 001 is an as-yet undescribed, substantially complete, fossil of a small troodontid dinosaur from the Late Jurassic Morrison Formation of east – central Wyoming...

. There was also the possible early tyrannosaur relative

Tyrannosauroidea

Tyrannosauroidea is a superfamily of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent beginning in the Jurassic Period...

Stokesosaurus clevelandi. Marshosaurus bicentesimus
Marshosaurus
Marshosaurus was a genus of medium sized theropod, with a size up to 5 or 6 meters in length and a skull about 60 cm long. It is known from parts of at least three individuals from the Morrison Formation of Utah and Colorado.The holotype is a left ilium, or upper pelvis bone found at the...

was a medium-sized theropod of uncertain classification that may have been related to the allosaurids.

Genus	Species	State	Material	Notes
Coelurus Coelurus Coelurus is a genus of coelurosaur dinosaur from the Late Jurassic period . The name means "hollow tail", referring to its hollow tail vertebrae...	C. fragilis	UT WY	"Postcranial skeleton."	A basal coelurosaurid Coelurosauria Coelurosauria is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. In the past, it was used to refer to all small theropods, although this classification has been abolished... about 2.3 m (7.5 ft) long.
	C. gracilis	WY
	Indeterminate.	CO
Koparion Koparion Koparion is a genus of small theropod dinosaur, known only from isolated teeth. Koparion douglassi, the type specimen, was described by Chure in 1994, who believed it to be a coelurosaurian theropod, possibly one of the oldest known troodontids. Found in Utah, the fossil is from the late Jurassic...	K. douglassi	UT		A small theropod Theropoda Theropoda is both a suborder of bipedal saurischian dinosaurs, and a clade consisting of that suborder and its descendants . Dinosaurs belonging to the suborder theropoda were primarily carnivorous, although a number of theropod groups evolved herbivory, omnivory, and insectivory... thought to be one of the oldest known Troodontid Troodontidae Troodontidae is a family of bird-like theropod dinosaurs. During most of the 20th century, troodontid fossils were few and scrappy and they have therefore been allied, at various times, with many dinosaurian lineages... s.
Palaeopteryx Palaeopteryx Palaeopteryx is a genus of theropod dinosaur now considered a nomen dubium. It was named and misidentified by J. A. Jensen in 1981, then redescribed by Jensen and K. Padian in 1989. At that time the binomial Palaeopteryx thomsoni was deemed invalid by Jensen...	P. thomsoni	CO
Ornitholestes Ornitholestes Ornitholestes was a small theropod dinosaur of the late Jurassic of Western Laurasia . To date, it is known only from a single partial skeleton, and badly crushed skull found at the Bone Cabin Quarry near Medicine Bow, Wyoming, in 1900...	O. hermanni	UT WY	"Skull and associated postcranial skeleton."	A small basal coelurosaurid Coelurosauria Coelurosauria is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. In the past, it was used to refer to all small theropods, although this classification has been abolished... about 2 m (6.5 ft) long.
Stokesosaurus Stokesosaurus Stokesosaurus is a genus of small , early tyrannosaur from the Late Jurassic period of Utah and England. It was named after Utah geologist William Lee Stokes...	S. clevelandi	UT	"Illium, associated elements and pelvic cranial material. [sic]"	A possible early tyrannosauroid Tyrannosauroidea Tyrannosauroidea is a superfamily of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent beginning in the Jurassic Period... about 4 m (13 ft) in length.
Tanycolagreus Tanycolagreus Tanycolagreus is a genus of coelurid theropod from the Late Jurassic of North America. The holotype is a partial skeleton recovered from the Bone Cabin Quarry West locality, Albany County, Wyoming, from the Morrison Formation...	T. topwilsoni			A basal coelurosaurid Coelurosauria Coelurosauria is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. In the past, it was used to refer to all small theropods, although this classification has been abolished... about 3.4 m (11.3 ft) long, similar in appearance to Coelurus Coelurus Coelurus is a genus of coelurosaur dinosaur from the Late Jurassic period . The name means "hollow tail", referring to its hollow tail vertebrae... .

Misc

Genus	Species	State	Member	Material	Notes
Edmarka Edmarka Edmarka is a genus of dinosaur from the Late Jurassic of North America. The name honors scientist Bill Edmark. It was a theropod closely related to Torvosaurus, and may, in fact, be a junior synonym of that genus. Its fossils, including a partial skeleton, were found at Como Bluff, Wyoming.The...	E. rex	WY			A megalosaurid similar in appearance to Torvosaurus Torvosaurus Torvosaurus is a genus of large theropod dinosaur that lived during the Late Jurassic period... .
Marshosaurus Marshosaurus Marshosaurus was a genus of medium sized theropod, with a size up to 5 or 6 meters in length and a skull about 60 cm long. It is known from parts of at least three individuals from the Morrison Formation of Utah and Colorado.The holotype is a left ilium, or upper pelvis bone found at the...	M. bicentesimus	CO UT		Partial skeleton, including part of a skull.	A medium-sized avetheropod Tetanurae Tetanurae, or "stiff tails", is a clade that includes most theropod dinosaurs, as well as birds. Tetanurans first appear during the early or middle Jurassic Period.-Definition:... about 6 m (20 ft) in length. Further classification is indeterminate.
Torvosaurus Torvosaurus Torvosaurus is a genus of large theropod dinosaur that lived during the Late Jurassic period...	T. tanneri	CO UT WY	Brushy Basin	"Partial skeletons of at least [three] individuals."	A large, robust megalosaurid reaching lengths of up to 11 m (35 ft). One of the largest carnivores of the formation.

Ornithopods

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

Stegosaurs

Stegosaur tracks were first recognized in 1996

1996 in paleontology

-Newly named crustaceans:-Dinosaurs:* In the summer excavation resumed on the Talkeetna Mountains Hadrosaur, discovered in a quarry near the Glenn Highway, approximately 150 miles northeast of Anchorage.-Newly named dinosaurs:...

from a hindprint-only trackway discovered at the Clevland-Lloyd quarry, which is located near Price, Utah. Two years later

1998 in paleontology

-Amphibians:A. C. Henrici. 1998. A new pipoid anuran from the Late Jurassic Morrison Formation at Dinosaur National Monument, Utah. Journal of Vertebrate Paleontology 18:321-332-Dinosaurs:...

, a new ichnogenus called Stegopodus was erected for another set of stegosaur tracks which were found near Arches National Park, also in Utah. 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. From this, scientists were able to successfully predict the appearance of stegosaur tracks in 1990

1990 in paleontology

-newly named:-Newly named taxa:-Dinosaurs:* All Anatosaurus species except A. copei were moved to the previously existing genus Edmontosaurus by Brett-Surman* "Seismosaurus" gastroliths documented.-Newly named dinosaurs:...

, six years in advance of the first actual discovery of Morrison stegosaur tracks. Since the erection of Stegopodus, more trackways have been found, however none have preserved traces of the front feet, and stegosaur traces remain rare.

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