Paleobiota of the Morrison Formation: Wikis

  
  

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The distinctive banding of the Morrison Formation, a group of rock layers that occur throughout Dinosaur National Monument and the source of fossils like those found at the Dinosaur Quarry.

The Morrison Formation is a distinctive sequence of Late Jurassic sedimentary rock that is found in the western United States, which has a wide assortment of taxa represented in its fossil record, including dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone and limestone and is light grey, 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.

Contents

Vertebrate fauna

(mostly from Foster [2003], with additional material in the mammal section after [1]; the higher-level classifications will vary as new finds are made. Only described taxa are included, so several Nomina nuda and undescribed taxa are left out)

Amphibians

According to museum curator John Foster, "frogs are known from several sites in the Morrison Formation but are not particularly well represented."[1] The history of Morrison anuran discoveries began with the recovery of remains from Reed's Quarry 9 near Como Bluff Wyoming. The new genus Eobatrachus was erected for some of these remains by O. C. Marsh, but the material was later considered non-diagnostic. Decades later another dubious anuran genus, Comobatrachus was erected for addition fragmentary remains. Despite the erection of multiple new names, scientists only recognize two legitimate frog species from the Morrison, Enneabatrachus hechti[2] and Rhadinosteus parvus.[3]

Frogs of the Morrison Formation
Taxa Presence Notes Images

Order:

  1. Indeterminate remains.[4]
  • Geographically present in Colorado, Wyoming, and Utah.[1] The best specimens are found in Dinosaur National Monument and Quarry 9.[1]
  1. Present in Stratigraphic zones 2 and 4.[4]
A modern frog from the same family as Enneabatrachus hechti, the discoglossidae.
A modern frog from the same family as Rhadinosteus parvus, the rhinophrynidae.
A modern pelobatid.

Genus:

  1. E. hechti[2]
  • Present in Stratigraphic zone 5.[4]
  1. One specimen has been recovered from Quarry 9 of Como Bluff in Wyoming and another specimen was later reported from Dinosaur National Monument.[2]
  • A small discoglossid frog whose name means "nine frog" after the quarry in which it was discovered.[2]
  1. The Como Bluff specimen was an illium only a few millimeters long.[2] E. hechti's live weight would have only been a few grams.[2]

Family:

  1. Indeterminate remains.[6]
  • A specimen has been recovered from Quarry 9 of Como Bluff in Wyoming.[6] Present in Stratigraphic zones 5 and 6.[4]
  • The anuran family containing modern spadefoot toads.[6]
  1. Known from the illium of an unnamed but indeterminate species.[6] This illium is larger than that of Enneabatrachus.[6]

Genus:

  1. R. parvus[3]
  • Present in Stratigraphic zone 6.[4]
  1. Found at the Rainbow Park site in Utah's Dinosaur National Monument.[3] Known from several slabs of rock which contain multiple partial specimens in association.[3]
  • A pipoid frog whose generic name means "slender bone."[3] It may have been a member of the rhinophrynidae.[3]
  1. Only about 42 mm (1.6 inches) long in life.[3] The R. parvus binomen means "small slender bone."[3]
Amphibians of the Morrison Formation
Taxa Presence Notes Images

Order:

  1. Indeterminate remains.[4]
  2. "Caudata B."[4]
  • Present in stratigraphic zones 2, 4, and 5.[4]
  • Present in stratigraphic zone 6.[4]
A modern frog from the same family as Enneabatrachus hechti, the discoglossidae.

Genus:

  1. C. marshi

Represented by a femur from Como Bluff.

  • Considered a nomen dubium based on non-distinctive remains and cannot be classified in detail.

Genus:

  1. I. hechti
Found in Dinosaur National Park.
  • Present in stratigraphic zone 6.[4]
  • A basal salamandroid closely related to today's advanced salamanders.

Dinosaurs

Indeterminate Dinosaurs of the Morrison Formation
Taxa Presence Notes Images

Superorder:

  1. Eggs.[7]
  1. Geographically present in Utah, USA.[7]

Ornithischian dinosaurs

The herbivorous ornithischian dinosaurs were diverse but not as common as sauropods in the Morrison. Unclassified members include the "Fruita Echinodon", a possible heterodontosaurid, and the dubious Tichosteus lucasanus and T. aequifacies. Plate-backed stegosaurids included Hesperosaurus mjosi, Hypsirophus discursus, Stegosaurus armatus (?including S. ungulatus), S. stenops, and "S." longispinus. Armored dinosaurs that weren't stegosaurs were unknown in the formation until the 1990s. Two have been named: Gargoyleosaurus parkpinorum and Mymoorapelta maysi. Ornithopods, bipedal herbivores, came in several types. Small "hypsilophodonts" included Drinker nisti, Laosaurus celer, "L." gracilis, Nanosaurus agilis, Othnielia rex, and Othnielosaurus consors. Larger but similar-looking dryosaurids were represented by Dryosaurus altus and the camptosaurid Camptosaurus aphanoecetes, which is currently known only from Dinosaur National Monument. Still larger was the more common Camptosaurus dispar, probably including Brachyrophus altarkansanus and Symphyrophus musculosus. Dryosaurids and camptosaurids were early iguanodonts, a group that would later spawn the duck-billed dinosaurs.

Indeterminate Ornithischians of the Morrison Formation
Taxa Presence Notes Images

Order:

  1. Indeterminate remains.[7]
  1. Geographically present in Utah, USA.[7]
Cerapods of the Morrison Formation
Taxa Presence Notes Images

Genus:

  1. C. aphanoecetes
  2. C. dispar[7]
  3. Camptosaurus sp.[7]

Present at Como Bluff. C. aphanoecetes is known from Dinosaur National Monument.

  • Present in stratigraphic zones 2-6.[4]
  1. Placeholder.
  2. Geographically present in Utah, USA.[7]
  3. Geographically present in Utah, USA.[7]
Life restoration of Othnielosaurus
Life restoration of Camptosaurus

Genus:

  1. D. nisti
Found at Como Bluff.
  • Present in stratigraphic zones 5 and 6.[4]
A basal hypsilophodont about 2 m long.

Genus:

  1. D. altus[7]

Specimens present from Como Bluff, Bone Cabin Quarry, and Dinosaur National Monument as well as other sites throughout Colorado, Wyoming, and Utah.

  • Present in stratigraphic zones 2-6.[4]
  1. Geographically present in Utah, USA.[7]

Genus:

Found from the Fruita Paleontological Area.
  • Present in stratigraphic zone 4.[4]
A small heterodontosaur.

Genus:

  1. Tracks.[7]
  1. Geographically present in Utah, USA.[7]

Genus:

  1. "L. celer
  2. "L. gracilis"
Found in Como Bluff. Considered dubious due to fragmentary remains.

Genus:

  1. N. agilis
Specimens found in Colorado and Wyoming. A small ornithopod, possibly a hypsilophodont

Genus:

  1. O. rex[7]
Specimens found in Wyoming, Utah, and Colorado.
  1. Geographically present in Utah, USA.[7]
A small hypsilophodont 2 m in length.

Genus:

  1. O. consors
Present at Como Bluff.
  • Present in stratigraphic zones 2-5.[4]
A basal hypsilophodont about 2 m long.
Thyreophorans of the Morrison Formation
Taxa Presence Notes Images

Genus:

  1. G. parkpinorum
Present at Bone Cabin Quarry.
  • Present in stratigraphic zones 2.[4]
An early ankylosaur, possibly a polocanthid, similar to Mymoorapelta in appearance.
Gargoyleosaurus
Hesperosaurus
Mymoorapelta
Stegosaurus in Field Museum

Genus:

  1. H. mjosi
Located low in the formation in Wyoming.
  • Present in stratigraphic zone 1.[4]
A stegosaurid more primitive than Stegosaurus with a broader skull and longer, lower dermal plates. About 7.6 m in length.

Genus:

  1. M. maysi
Found in Brushy Basin Member of western Colorado.
  • Present in stratigraphic zones 4 and 5.[4]
An early ankylosaur, possibly a polocanthid.

Infraorder:

  1. Indeterminate remains.[4]
  • Present in stratigraphic zones 1 and 4.[4]

Infraorder:

  1. Tracks.[7]
  1. Geographically present in Utah, USA.[7]

Family:

  1. Indeterminate remains.[7]
  1. Geographically present in Utah, USA.[7]
  1. "(=Stegosaurus affinis)"[7]

Genus:

  1. S. armatus[7]
  2. S. stenops[7]
  3. S. ungulatus
  4.  ?S. longispinus[7]
  5. Stegosaurus sp.[7]

Specimens present throughout the formation in sites such as Dinosaur National Monument, Como Bluff, and the Marsh-Felch Quarry.

  • Present in stratigraphic zones 2-6.[4] Remains possibly referrable to Stegosaurus have been recovered from stratigraphic zone 1.[4]
  1. Geographically present in Utah, USA.[7]
  2. Geographically present in Utah, USA.[7]
  3. Geographically present in Utah, USA.[7]
  4. Geographically present in Utah, USA.[7]
  5. Geographically present in Utah, USA.[7]
  1. Placeholder.
  2. Placeholder.
  3. May be synonymous with S. armatus.

Sauropod dinosaurs

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 an early titanosaur) and Haplocanthosaurus. Sauropods including Haplocanthosaurus priscus, H. delfsi, and the diplodocids Dystrophaeus and Eobrontosaurus 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 C. lewisi, were very common. Also common were long, low diplodocids, like Apatosaurus ajax, A. excelsus (formerly "Brontosaurus"), A. louisae, A. parvus, Atlantosaurus montanus, Barosaurus lentus, Diplodocus longus, D. carnegii, "D." hayi, "D." lacustris, Dyslocosaurus polyonychius.

By the late Morrison, gigantic diplodocids (or likely diplodocids) had appeared, including Diplodocus hallorum (formerly Seismosaurus), Supersaurus vivianae, Amphicoelias altus, and the largest of all, A. 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.[8]

Sauropod Dinosaurs of the Morrison Formation
Taxa Presence Notes Images

Genus:

  1. A. altus
  2. A. fragillimus
Partial vertebrae of A. fragillimus found at Garden Park in 1877. A. altus is known from less fragmentary remains.
  • Present in stratigraphic zone 6.[4]
Large diplodocids about 25 m in length. A. fragillimus may have obtained a length of up to 60 m in length based on a single neural arch 1.5 m tall.
Diplodocus skull from Bone Cabin Quarry
Cope's illustration of the Amphicoelias fragillimus specimen
Life restoration of Brachiosaurus
Camarasaurus lentus skull

Genus:

  1. A. ajax
  2. A. excelsus
  3. A. louisae[7]
  4. A. parvus

Specimens found across the formation in Colorado, Oklahoma, Wyoming, and Utah.

  • Present in stratigraphic zones 2-6.[4]
  1. Placeholder.
  2. Placeholder.
  3. Geographically present in Utah, USA.[7]
  4. Placeholder.

Genus:

  1. B. lentus[7]

Found in Dinosaur National Monument as well as other sites in South Dakota and Wyoming.

  • Present in stratigraphic zones 2-5.[4]
  1. Geographically present in Utah, USA.[7]
A diplodocid about 24 m in length, similar in appearance to Diplodocus.

Genus:

  1. Brachiosaurus cf. altithorax[7]

Specimens found in Colorado.

  • Present in stratigraphic zones 2-4 and 6.[4]
  1. Geographically present in Utah, USA.[7]

Genus:

  1. C. supremus
  2. C. lentus[7]
  3. C. grandis
  4. C. lewisi
  5. Camarasaurus sp.
  • The most common sauropod of the formation.[9 ] Specimens have been found throughout Colorado, Wyoming, and Utah. Present in stratigraphic zones 2-6.[4]
  1. Placeholder.
  2. Geographically present in Utah, USA.[7]
  3. Placeholder.
  4. Placeholder.
  5. Geographically present in Utah, USA.[7]
  • Camarasaurs reached an adult size of about 18 m in length.[9 ] A Camarasaurus pelvis from the Cleveland-Lloyd Quarry shows evidence of gouging that has been attributed to Allosaurus. A juvenile specimen was recovered from Dinosaur National Monument in Utah.[9 ]

Family:

  1. Possible indeterminate diplodocid remains.
  1. Geographically present in Utah, USA.[7]

Genus:

  1. D. carnegii[7]
  2. D. hayi
  3. D. hallorum
  4. D. longus[7]
  5. Diplodocus sp.

Present from Marsh-Felch Quarry and Dinosaur National Monument as well as other sites in Wyoming and Utah.

  • Present in stratigraphic zones 1-6.[4]
  1. Geographically present in Utah, USA.[7]
  2. Placeholder.
  3. Present in stratigraphic zone 5.[4]
  4. Geographically present in Utah, USA.[7]
  5. Geographically present in Utah, USA.[7]

Genus:

  • Present in stratigraphic zone 1.[4]

Genus:

  1. E. yahnahpin
Found lower in the formation at Como Bluff. An apatosaurine diplodocid slightly more primitive than Apatosaurus.

Genus:

  1. H. priscus
  2. H. delfsi
  3.  ?Haplocanthosaurus sp.

Present in Marsh-Felch Quarry and Garden Park.

  • Present in stratigraphic zones 1, 2, and 4.[4]
  1. Placeholder.
  2. Placeholder.
  3. Geographically present in Utah, USA.[7]
  • Small haplocanthosaurs of indeterminate classification, ranging about 14 m long.

Genus:

  1. Indeterminate remains.[7]
  2. Tracks.[7]
  • Specimen found from Dry Mesa Quarry.
  1. Geographically present in Utah, USA.[7]
  2. Geographically present in Utah, USA.[7]
A large diplodocid about 38 m in length.

Genus:

  1. S. vivianae
Specimen found from Dry Mesa Quarry.
  • Present in stratigraphic zones 5.[4]
A large diplodocid about 38 m in length.

Genus:

  1. S. emilieae
Specimens found from southern Montana. A small diplodocid about 15m in length.

Theropod dinosaurs

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, Elaphrosaurus sp., and the megalosaur Torvosaurus tanneri (?including Edmarka rex). Allosaurids included the common Allosaurus fragilis (including Epanterias amplexus), A. new species, Antrodemus valens, and giant Saurophaganax maximus.

Coelurosaurs, more derived types more closely related to birds, included Coelurus fragilis, Ornitholestes hermanni, Tanycolagreus topwilsoni, the possible troodontid Koparion douglassi, and the definite troodontid WDC DML 001. There was also the possible early tyrannosaur relative Stokesosaurus clevelandi. Marshosaurus bicentesimus was a medium-sized theropod of uncertain classification that may have been related to the allosaurids.

Indeterminate Theropods of the Morrison Formation
Taxon Presence Notes Images

Suborder:

  1. Indeterminate remains.[7]
  2. Tracks.[7]
  1. Geographically present in Utah, USA.[7]
  2. Geographically present in Utah, Arizona, USA.[7]
Ceratosaurs of the Morrison Formation
Taxon Presence Notes Images

Genus:

  1. C. dentisulcatus[7]
  2. C. magnicornis
  3. C. nasicornis[7]
  4. Ceratosaurus sp.[7]
  • Present at Garden Park, the Fruita Paleontological Area, Dinosaur National Monument, the Marsh-Felch Quarry, Como Bluff, the Mygatt-Moore Quarry, the Agate Basin, Dry Mesa Quarry, Bone Cabin Quarry, and the Cleveland-Lloyd Quarry. Present in stratigraphic zones 2 and 4-6.[4]
  1. Geographically present in Utah, USA.[7]
  2. Placeholder.
  3. Geographically present in Utah, USA.[7]
  4. Geographically present in Utah, USA.[7]
  • Large ceratosaurs about 6 m in length with large nasal horns on their snouts as well as two smaller horns above the eyes.
Life restoration of Ceratosaurus
Elaphosaurus

Genus:

Specimens collected from Marsh-Felch Quarry.
  • Present in stratigraphic zones 2-4.[4]
A medium-sized ceratosaur about 6 m in length.
Tetanurans of the Morrison Formation
Taxon Presence Notes Images

Genus:

  1. A. fragilis[7]
  2. "A. jimmadseni"
  3. Unnamed species.[7]
  • The most common theropod to be found. Present in stratigraphic zones 1-6.[4]
  1. Geographically present in Utah, USA.[7]
  2. Placeholder.
  3. Geographically present in Utah, USA.[7]
Large allosaurid carnosaurs about 8.5 m in length.
Allosaurus skull from Dinosaur National Monument, still partially encased in matrix
Life restoration of Coelurus
Marshosaurus skull at the Carnegie Museum of Natural History

Genus:

  1. C. fragilis[7]
Found from Como Bluff.
  • Present in stratigraphic zones 2 and 5.[4]
  1. Geographically present in Utah, USA.[7]
A basal coelurosaurid about 2.3 m long.

Genus:

  1. E. rex
Specimen found from Como Bluff. A megalosaurid similar in appearance to Torvosaurus.

Genus:

  1. E. amplexus
Present at Garden Park and another site in the northern Front Range of Colorado. An allosaurid about 12.1 m in length, similar in appearance to Allosaurus.

Genus:

  1. K. douglassi[7]
Single tooth from Garden Park.

Present in stratigraphic zone 6.[4]

  1. Geographically present in Utah, USA.[7]
A small theropod thought to be the oldest known Troodontid.

Genus:

  1. M. bicentesimus[7]
Found at Cleveland-Lloyd Quarry,
  • Present in stratigraphic zones 3 and 5.[4]
  1. Geographically present in Utah, USA.[7]
A medium-sized avetheropod about 6 m in length. Further classification is indeterminate.

Genus:

  1. O. hermanni[7]
Specimens found from Bone Cabin and Dry Mesa Quarry.
  • Present in stratigraphic zone 2.[4] Remains possibly referrable to Stokesosaurus have been recovered from stratigraphic zone 5.[4]
  1. Geographically present in Utah, USA.[7]
A small basal coelurosaurid about 2 m long.

Genus:

  1. S. maximus
Found from Stovall's Quarry 1 in Oklahoma.
  • Present in stratigraphic zone 5.[4]
A large allosaurid reaching lengths of up to 12.5 m. The largest carnivore known from the formation.

Genus:

  1. S. clevelandi[7]
Specimen present from Cleveland-Lloyd Quarry.
  • Present in stratigraphic zone 5.[4] Remains possibly referrable to Stokesosaurus have been recovered from stratigraphic zone 2.[4]
  1. Geographically present in Utah, USA.[7]
A possible early tyrannosauroid about 4 m in length.

Genus:

  1. T. topwilsoni
Specimens found from Bone Cabin and Cleveland-Lloyd quarries.
  • Present in stratigraphic zone 2.[4] Remains possibly referrable to Stokesosaurus have been recovered from stratigraphic zone 5.[4]
A basal coelurosaurid about 3.4 m long, similar in appearance to Coelurus.

Genus:

  1. T. tanneri[7]
  • Specimens found from the Dry Mesa Quarry. Present in stratigraphic zones 3 and 5.[4]
  1. Geographically present in Utah, USA.[7]
A large, robust megalosaurid reaching lengths of up to 11 m. One of the largest carnivores of the formation.

Fish

Although the paleoclimate of the Morrison formation was semiarid with only seasonal rainfall, there were enough bodies of water to support a diverse ichthyofauna.[10] Although abundant, fish remains are constrained to only certain locations within the formation.[10] Microvertebrate sites in Wyoming are dominated by fish remains.[10]

Fish of the Morrison Formation
Taxa Presence Notes Images

Order:

  1. Indeterminate remains.[4]
  1. Remains have been recovered from Ninemile Hill and a microvertebrate site in the Black Hills.[10] Found in stratigraphic zones 2, 4, and 5.[4]
  • Morrison actinopterygians generally have no close modern relatives.[10]
  1. The Wyoming microvertebrate remains are extracted from the sediment by screenwashing.[10]
Ceratodus
Ceratodus
Leptolepis

Order:

  1. Amiidae[10]
  • Found in stratigraphic zones 2, 3, and 4.[4]
  1. Found at a fossil site not far from Cañon City, Colorado.[10]
  1. Remains usually in a state of rather complete preservation.[10]

Genus:

  1. C. fossanovum[10]
  2. C. ?frazieri[10]
  3. C. guentheri[10]
  4. C. robustus[10]
  • Tooth plates from Saltwash to upper Brushy Basin Member found in many areas of the formation. Found in stratigraphic zones 2-6.[4]
  • A lungfish genus whose members ranged from 1 to 2 m in length and weights of up to 79 pounds.[10] However most Morrison lungfish would have been on the smaller side of that range.[10] These species are believed to have had similar diets to extant lungfish.[10] The modern lungfish Neoceratodus is physically very similar to Ceratodus.[10]

Subclass:

  • Remains usually in a state of rather complete preservation.[10]

Division:

  • Geographically present in the western part of Colorado, where remains have been recovered from "a level above the Mygatt-Moore Quarry."[10]
  • Largely complete remains of small individuals have been consistently recovered for over 15 years.[10]

Genus:

  1. H. hawesi[11]
Fossils found in Colorado preserved in the shallow lake deposits of the Fruita Paleontological Area and Rabbit Valley.
  1. Found in stratigraphic zone 5.[4]
  • A small fish of the division Halecostomi about 7.6 cm in length and 5g of live mass which probably preferred quiet water. Its fossils prominently preserve its thick interlocking scales.
  1. Co-occurs with Morrolepis in the Rabbit Valley deposits.

Family:

  1. cf. Leptolepis[5]
  • Geographically present in the western part of Colorado, where remains have been recovered from "a level above the Mygatt-Moore Quarry."[10]
  1. Known only from a single nearly complete skeleton found at Rabbit Valley, Colorado.[11] Found in stratigraphic zone 5.[4]
  • Largely complete remains of small individuals have been consistently recovered for over 15 years.[10]
  1. A 13 cm (5 inch) fish that was deeper bodied than its co-occurring contemporaries Morrolepis and Hulettia.[11] The Morrison cf. Leptolepis probably had a live mass of about 37g.[11] It is the only teleost fish known from the formation and was morphologically more highly derived than other Morrison fish.[11] It is believed to have fed on contemporary fish and small invertebrates.[11]

Genus:

  1. M. schaefferi[12]
  • Fossils found near the Mygatt-Moore quarry the in Rabbit Valley, Colorado. Known from only five specimens.[12]
  1. Found in stratigraphic zone 5.[4]
  • A palaeoniscoid with forward-set eyes positioned past the front end of the lower jaw. It had a tall dorsal fin set far back on the body and an asymmetrical caudal fin.[12] Adult specimens would reach about 20 cm in length and 113 g (4oz) in mass.[12]
  1. The first specimen was nearly complete, the four subsequent findings vary in completeness.[12]

Order:

  • Paleoniscoidea[10]
  • Geographically present in the western part of Colorado, where remains have been recovered from "a level above the Mygatt-Moore Quarry."[10]
  • Largely complete remains of small individuals have been consistently recovered for over 15 years.[10]

Superfamily:

  1. Genus and species indeterminate.[13]
  1. Only a single specimen from Dinosaur National Monument in Utah has been recovered.[13]
  • Pycnodontoids were "deep-bodied and laterally compressed fish" whose tooth morphology suggest that they preyed on small contemporary invertebrates. They may have resembled modern butterfly fish.[13]
  1. A single tooth is the only known remains.[13]

Mammals

Many types of early mammals are known from the Morrison; almost all of them were small, rodent-like animals. Unclassified types include the digger Fruitafossor windscheffelia. Docodonts included the common genus Docodon, represented by D. victor, D. striatus, and D. superbus, and Peraiocynodon sp. Multituberculates, a common type of early mammal, were represented by Ctenacodon serratus, C. laticeps, C. scindens, "C." brentbaatar, Glirodon grandis, Psalodon fortis, ?P. marshi, P. potens, and Zofiabaatar pulcher. Triconodonts present included Aploconodon comoensis, Conodon gidleyi (AKA Phascolodon and Phascolotheridium), Priacodon ferox, P. fruitaensis, P. gradaevus, P. lulli, P. robustus, Triconolestes curvicuspis, and Trioracodon bisulcus.

Symmetrodonts were represented by Amphidon superstes, Eurylambda aequicrurius (probably Tinodon), and Tinodon bellus (including T. lepidus). Finally, two families of Dryolestoidea were present: Paurodontidae, including Araeodon intermissus, Archaeotrigon brevimaxillus, A. distgamus, Comotherium richi, Euthlastus cordiformis, Foxraptor atrox, Paurodon valens, Pelicopsis dubius, and Tathiodon agilis; and Dryolestidae, including Amblotherium gracilis, Dryolestes obtusus (common genus), D. priscus, D. vorax, Laolestes eminens, L. grandis, and Miccylotyrans minimus.

In 2009, a study by J. R. Foster was published which estimated the body masses of mammals from the Morrison Formation by using the ratio of dentary length to body mass of modern marsupials as a reference. Foster concludes that Docodon was the most massive mammal genus of the formation at 141g and Fruitafossor was the least massive at 6g. The average Morrison mammal had a mass of 48.5g. A graph of the body mass distribution of Morrison mammal genera produced a right-skewed curve, meaning that there were more low-mass genera.[14]

Mammals of the Morrison Formation
Taxa Presence Notes Images

Genus:

  1. A. superstes
Found at Como Bluff.
  • Present in stratigraphic zone 5.[4]
Life restoration of Fruitafossor

Genus:

  1. A. comoensis
Present at Como Bluff
  • Present in stratigraphic zone 5.[4]

Genus:

  1. D. victor
  2. D. striatus
  3. D. affinis
  4. D. crassus
  5. D. superus

Specimens present at Como Bluff and Garden Park.

  • Present in stratigraphic zones 2-6.[4]
  • docodonts about 10 cm in length. The most massive genus of the formation, with an average of 141g.[14]

Genus:

  1. F. windscheffeli
Found from the Fruita Paleontological Area.
  • Present in stratigraphic zone 4.[4]
  • A burrowing mammal of indeterminant classification, thought to be closely related to therians. Fruitafossor had the smallest body mass of all Morrison mammals, at a mere 6g.[14]

Genus:

  1. C. serratus
  2. C. laticeps
  3. C. nanus
  4. C. scindens
Present at Como Bluff.
  • Present in stratigraphic zone 5.[4] Remains possibly referrable to Ctenacodon have been recovered from stratigraphic zone 2.[4]

Genus:

  1. P. potens
  2. P. fortis
  3. ?P. marshi
Specimens known from Como Bluff and Little Houston Quarry
  • Present in stratigraphic zones 2 and 5.[4]

Genus:

  1. Z. pulcher
Found at Como Bluff.
  • Present in stratigraphic zone 6.[4]

Genus:

  1. G. grandis
Specimens found from the Fruita Paleontological Area and Rainbow Park.
  • Present in stratigraphic zones 4 and 6.[4]

Genus:

  1. P. robustus
  2. P. gradaevus
  3. P. lulli
  4. P. fruitaensis
Present at Como Bluff and the Fruita Paleontological Area.
  • Present in stratigraphic zones 4-6.[4]

Genus:

  1. T. bisulcus
Found at Como Bluff.
  • Present in stratigraphic zone 5.[4]

Genus:

  1. C. gidleyi
Present at Como Bluff
  • Present in stratigraphic zone 5.[4]

Genus:

  1. T. curvicuspis
Specimens found from Rainbow Park.
  • Present in stratigraphic zones 4.[4]

Genus:

  1. T. bellus
  2. T. lepidus
Found at Como Bluff.
  • Present in stratigraphic zone 5.[4]

Genus:

  1. E. aequicrurius
Found at Como Bluff.
Mammals of the Morrison Formation
Taxa Presence Notes Images

Genus:

  1. A. gracilis
Present from the Marsh-Felch Quarry at Garden Park.
  • Present in stratigraphic zones 2, 3, and 5.[4]
Life restoration of Fruitafossor

Genus:

  1. A. intermissus
Found at Como Bluff and Dinosaur National Monument.
  • Present in stratigraphic zone 5.[4]

Genus:

  1. A. brevimaxillus
  2. A. distagmus

Found at Como Bluff

Paurodontid dryolestoids similar in appearance to Paurodon.

Genus:

  1. P. valens
Found at Como Bluff.
  • Present in stratigraphic zone 5.[4]

Genus:

  1. T. agilis
Found at Como Bluff.
  • Present in stratigraphic zone 5.[4]

Genus:

  1. F. atrox
Found at Como Bluff.
  • Present in stratigraphic zone 6.[4]

Genus:

  1. E. cordiformis
Found at Como Bluff.
  • Present in stratigraphic zones 5 and 6.[4]

Genus:

  1. P. dubius
Found at Como Bluff.

Genus:

  1. C. richi
Present at Como Bluff.
  • Present in stratigraphic zone 5.[4]

Genus:

  1. D. priscus
  2. D. tenax
  3. D. obtusus
Found at Como Bluff.
  • Present in stratigraphic zones 2, 5, and 6.[4]

Genus:

  1. L. eminens
  2. L. grandis
Found at Como Bluff as well as other sites in Wyoming.
  • Present in stratigraphic zones 5 and 6.[4]

Genus:

  1. M. minimus
A specimen present at Como Bluff.

Other reptiles

Crocodylomorphs

Crocodiles of a variety of sizes and habitats were common Morrison animals. Cursorial mesosuchians, or small terrestrial running crocs, included Hallopus victor and "Fruitachampsa callisoni". More derived crocodilians included Goniopholis felix (common), G. gilmorei, G. lucasi, G. stovalli, Hoplosuchus kayi, and Macelognathus vagans.

Crocodylomorphs of the Morrison Formation
Taxa Presence Notes Images

Genus:

  1. G. felix
  2. G. lucasii
  3. G. gilmorei
  4. G. stovalli
Specimens found at Lake's Quarry, Garden Park, Como Bluff, and other sites in Wyoming, Colorado, and Oklahoma.
  • Present in stratigraphic zones 2-6.[4]
Semiaquatic neosuchian Crocodylomorphs similar in appearance to modern crocodiles.
Goniopholis
Goniopholis
Hoplosuchus

Genus:

  1. E. delfsi
Present in Garden Park, Como Bluff, and Dry Mesa Quarry.
  • Present in stratigraphic zones 1, 3, 5, and 6.[4]
A goniopholid similar in appearance to Goniopholis.

Genus:

  1. "F. callisoni"
Found in several sites from the Brushy Basin Member within the Fruita Paleontological Area.
  • Confirmed in stratigraphic zone 4.[4] Remains possibly referable to "Fruitachampsa" have been found in Zone 2 as well.[4]
A small terrestrial crocodillian about 1 m in length.

Genus:

  1. M. vagans
Found in Como Bluff.
  • Present in stratigraphic zones 4 and 5.[4]
A sphenosuchian crocodylomorph

Genus:

  1. H. victor
Found at Garden Park.
  • Present in stratigraphic zone 6.[4]
A terrestrial crocodilian of uncertain classification.

Genus:

  1. H. kayi
Present at Dinosaur National Monument.
  • Present in stratigraphic zone 5.[4]
A primitive Crocodylomorph

Lizards

Squamates of the Morrison Formation
Taxa Presence Notes Images

Genus:

  1. S. utahensis[15]
  • Possibly present in stratigraphic zone 5.[4]
  1. A single set of remains were recovered from Dinosaur National Monument in Utah.[15]
  • A small scincomorph lizard of otherwise uncertain evolutionary affinities.[15] It is the only lizard genus endemic to the Morrison Formation.[15]
  1. The Dinosaur National Monument skeleton was only partially complete.[15]

Genus:

  1. Saurillodon sp.[16]
  • Present in stratigraphic zone 4.[4]
  1. Remains have been recovered from western Colorado's Fruita Paleontological Area.[16]
  • A scincomorph lizard whose remains have been found in Middle Jurassic strata in England and Scotland as well as Late Jurassic strata in Portugal in addition to the Morrison formation remains.[16]

Order:

  1. Indeterminate remains.[4]
  • Present in stratigraphic zones 2, 4, and 6.[4]
A scincomorph lizard.

Genus:

Specimens found from Como Bluff, Fruita Paleontological Area, and Rainbow Park.
  • Present in stratigraphic zones 4 and 5.[4]
A small scincomorph lizard with blunt teeth.

Genus:

Found at many sites including Como Bluff.
  • Present in stratigraphic zones 2, 4, and 5.[4]
An anguimorph lizard.

Genus:

  1. P. gilmorei
Present at the Fruita Paleontological Area.
  • Present in stratigraphic zone 4.[4]
An anguimorph lizard.

Infraorder:

  1. A jaw bone.[17]
  1. A single specimen has been recovered from western Colorado's Fruita Paleontological Area.[17]
  • Randy Nydam concluded that the remains were of an anguimorph lizard of unknown classification.[17]
  1. The jaw was originally suspected to be from a snake, and despite Nydam's suggestion that it was from an anguimorph, some still support the first explanation.[17]

Turtles

Turtles (Testudines) are very common fossils in the Morrison, due to their bony shells. The most common were Glyptops plicatus (very common) and Dinochelys whitei (also common, but not as common as Glyptops). Also present were Dorsetochelys buzzops and Uluops uluops.

Turtles of the Morrison Formation
Taxa Presence Notes Images

Superorder:

  1. Indeterminate remains.[4]
  1. Present in stratigraphic zones 1-6.[4]

Genus:

  1. G. plicatus
Nearly complete skeleton found at Garden Park. Fragmentary remains found in numerous sites in the formation.
  • Present in stratigraphic zones 1-6.[4]
A cryptodire turtle with a long skull and ridged shell.

Genus:

  1. D. whitei
Fossils found in many quarries including the Dry Mesa Quarry, Wolf Creek Quarry, Little Houston Quarry, Garden Park, and Como Bluff.
  • Present in stratigraphic zones 2, 4, and 6.[4]
A smooth-shelled cryptodire turtle.

Genus:

  1. U. uluops
Present at Como Bluff
  • Present in stratigraphic zone 6.[4]
A baenid cryptodire turtle with a blunt head and ridged shell.

Genus:

  1. D. buzzops
Found from upper formation.
  • Present in stratigraphic zone 6.[4]
A short-skulled baenid cryptodire turtle.

Misc

A variety of small reptiles were present in the Morrison Formation. Sphenodontia (the modern tuataras) were represented by the common Opisthias rarus, and Eilenodon robustus and Theretairus antiquus. Lizards (Squamata) were represented by Dorsetisaurus sp., Paramacellodus sp., Parviraptor gilmorei, Saurillodon sp., and Schilleria utahensis. Champsosaurs (Choristodera), a type of aquatic reptile superficially similar to crocodiles, were represented by Cteniogenys antiquus, a common genus.

Sphenodonts of the Morrison Formation
Taxa Presence Notes Images

Genus:

  1. O. rarus
Sites where fossils are found include Carnegie Quarry and Rainbow Park areas at Dinosaur National Monument as well as the Fruita Paleontological Area, Wolf Creek Quarry, the Uravan Locality, and the Kings View Quarry.
  • Present in stratigraphic zones 2 and 4-6.[4]
A sphenodontian similar in appearance to the modern Tuatara

Order:

  1. Indeterminate remains.[4]
  • Present in stratigraphic zones 2-6.[4]

Genus:

  1. T. antiquus
Specimens found from Como Bluff
  • Present in stratigraphic zones 5 and 6.[4]
A small sphenodontian.

Genus:

  1. E. robustus
Found in the Fruita Paleontological Area and other sites in Colorado and Utah.
  • Present in stratigraphic zone 4.[4]
A sphenodontian of relatively large size.
Champsosaurs of the Morrison Formation
Taxa Presence Notes Images

Genus:

  1. C. antiquus
Specimens found at Como Bluff and other sites in South Dakota, Wyoming, Oklahoma, and Utah.

Present in stratigraphic zones 2, 5, and 6.[4]

A champsosaur about 25 to 50 cm in length.

Pterosaurs

Pterosaurs are very uncommon fossils in the Morrison, because the fragility of their thin walled bones often prevented their remains from being preserved.[18] Despite being uncommon they are geographically widespread;[19] indeterminate pterosaur remains have been found in stratigraphic zones 2 and 4-6.[4] In addition to indeterminate remains, several species have been identified from both the rhamphorhynchoids (long-tailed pterosaurs) and pterodactyloids (short-tailed pterosaurs).[18] Since the 1970s and 80s, pterosaur finds have become more common, but are still rare.[18] Most Morrison pterosaurs have been found in marine and shoreline deposits.[18] Pterosaur tracks have been found in both the Tidwell and Saltwash members.[18] Morrison pterosaurs probably lived on fish, insects and scavenged dinosaur carcasses.[18]

Pterosaurs of the Morrison Formation
Taxa Presence Notes Images

Genus:

  1. H. gentryii[20]
  • Present in stratigraphic zone 2.[4]
  1. Found at Bone Cabin Quarry, Wyoming.[20]
  1. The original find was the front portion of a partial skull.[20]

Genus:

  1. K. insperatus[21]
  • Present in stratigraphic zone 4.[4]
  1. Remains recovered from the Small Quarry of Garden Park, Colorado.[21]
  1. Known from a partial skeleton recovered in association with a Stegosaurus specimen and "other small vertebrate material."[21]

Genus:

  1. M. ornithosphyos[22]
  • Present in stratigraphic zone 4.[4]
  1. The first known remains were recovered from a coarse sandstone deposit in the Dry Mesa Quarry.[22] Later remains referred to Mesadactylus were recovered from the Kingsview Quarry.[22] So far all known Mesadactylus fossils have been found in Colorado.[22]
  • A somewhat small pterodactyloid with a wingspan of about 1.8 m (6 ft.) and live mass of about 650 g (1.4 lbs).[22] It was the first genus of pterosaur to be known from more than one site in the formation and is also the Morrison pterosaur scientists know the most about.[22] The inarticulated and incomplete remain Dry Mesa find were all that was known of the genus until the Kingsview find in October, 2002.[22]
  1. The first remains of M. ornithosphyos were discovered in the 1970s in association with the remains of sauropods and other dinosaurs.[22] It had many cone-shaped teeth and may have eaten fish.[22]

Ichnogenus:

  • Geographically present in Oklahoma at Kenton.[23] An Arizonan trackway generally considered to be from the Summerville Formation may be Morrison.[23]
  • The Kenton specimen is kept in the University of Colorado's Dinosaur Tracks Museum in Denver.[23] The possible Arizonan Morrison tracks contain the type specimen of Pteraichnus saltwashensis, which is kept at the University of Utah.[23]
Dubious and indeterminate Pterosaurs of the Morrison Formation
Taxa Presence Notes Images

Genus:

  1. C. ostromi[24]
  • Present in stratigraphic zone 5.[4]
  1. A single specimen was found in Quarry 9 at Como Bluff, Wyoming.[24]
  • A rhamphorhynchoid pterosaur with a wingspan estimated by Peter Wellnhofer to be about 2.5 m.[24] It was apparently one of the larger Morrison pterosaurs.[24]
  1. A fossil metacarpal was found by O. C. Marsh's crew in the late 1800s and stored in the Yale Peabody Museum.[24] In 1981 Peter M. Galton erected the new genus and species to contain it.[24] However some now consider the single bone too non-diagnostic to justify the creation of a new taxon.[24]

Genus:

  1. D. montanus[25]
  • Present in stratigraphic zone 5.[4]
  1. The specimen was recovered from Quarry 5 in Como Bluff, Wyoming.[25]
  • A small pterodactyloid pterosaur with a wingspan of about 1 m and an adult mass of only 200g (7 ounces).[25] The genus is considered to be dubious because it was based on scant remains; only half of a fourth metacarpal has been found.[25] The specimen was recovered by a team working for O. C. Marsh during the bone wars.[25]
  1. For over 100 years it was the only Morrison pterosaur to have been named.[25] It also represented the first Jurassic pterosaur found in North America.[25]

Genus:

  1. L. priscus[19]
  1. The specimen was found in Quarry 9 in Como Bluff, Wyoming.[19]
  • Mistaken by O. C. Marsh for a bird, it was later determined by John Ostrom to be a pterosaur of indeterminate classification.[19]
  1. The original specimen was a "small, fragmentary skull."[19]

Genus:

  1. U. kateae[26]
  • Present in stratigraphic zone 1.[4]
  1. The specimen was recovered from the middle of the Tidwell Member at an outcrop near Moab, Utah.[26]
  • A dubious genus formerly considered a rhamphorhynchoid pterosaur based on partial skeletal remains,[26][27] but now is considered to be some indeterminate diapsid reptile.[28]
  1. Despite the taxonomic uncertainty, the find retains some scientific significance for being vertebrate remains found in an area of the Morrison that rarely preserves them.[26]

See also

References

  1. ^ a b c Foster, J. (2007). "Anura (Frogs)." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 135-136.
  2. ^ a b c d e f Foster, J. (2007). "Enneabatrachus hechti" Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. p. 137.
  3. ^ a b c d e f g h Foster, J. (2007). "Rhadinosteus parvus." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. p. 137.
  4. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd be bf bg bh bi bj bk bl bm bn bo bp bq br bs bt bu bv bw bx by bz ca cb cc cd ce cf cg ch ci cj ck cl cm cn co cp cq cr cs ct cu cv cw cx cy cz da db dc dd de df dg dh di dj dk dl dm dn Foster, J. (2007). "Appendix." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 327-329.
  5. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd be bf bg bh bi bj bk bl bm bn bo bp bq br bs bt bu bv bw bx by bz ca cb cc cd ce cf cg ch ci Foster, J. (2007). "Table 2.1: Fossil Vertebrates of the Morrison Formation." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 58-59.
  6. ^ a b c d e Foster, J. (2007). "Pelobatidae indet." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. p. 137.
  7. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd be bf bg bh bi bj bk bl bm bn bo bp bq br bs bt bu bv bw bx by bz ca cb cc cd ce cf cg ch ci cj ck cl cm cn co cp cq cr cs ct cu Weishampel, David B; et al. (2004). "Dinosaur distribution (Late Jurassic, North America)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 543–545. ISBN 0-520-24209-2.
  8. ^ Harris, J.D. and Dodson, P. (2004). "A new diplodocoid sauropod dinosaur from the Upper Jurassic Morrison Formation of Montana, USA." Acta Palaeontologica Polonica, 49(2): 197–210.
  9. ^ a b c "Camarasaurus." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. The Age of Dinosaurs. Publications International, LTD. p. 56. ISBN 0-7853-0443-6.
  10. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac Foster, J. (2007). "The Forgotten Aquatic Denizens: The Fish." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 129-131.
  11. ^ a b c d e f Foster, J. (2007). "Hulettia hawesi." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. p. 132-134.
  12. ^ a b c d e Foster, J. (2007). "Morrolepis schaefferi." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 131-132.
  13. ^ a b c d e Foster, J. (2007). "Pycnodontoidea." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. p. 135.
  14. ^ a b c Foster, J.R. 2009. Preliminary body mass estimates for mammalian genera of the Morrison Formation (Upper Jurassic, North America). PaleoBios 28(3):114-122.
  15. ^ a b c d e Foster, J. (2007). "Schilleria utahensis" Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. p. 145.
  16. ^ a b c Foster, J. (2007). "Saurillodon sp." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. p. 145.
  17. ^ a b c d e Foster, J. (2007). "Anguimorpha?" Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. p. 146.
  18. ^ a b c d e f Foster, J. (2007). "Soaring Overhead: The Pterosaurs." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 157-158.
  19. ^ a b c d e f Foster, J. (2007). "Laopteryx priscus." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. p. 160.
  20. ^ a b c d e Foster, J. (2007). "Harpactognathus gentryii." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. p. 160.
  21. ^ a b c d e Foster, J. (2007). "Kepodactylus insperatus." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. p. 160.
  22. ^ a b c d e f g h i Foster, J. (2007). "Mesadactylus ornithosphyos." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 159-160.
  23. ^ a b c d e Lockley, M.; Harris, J.D.; and Mitchell, L. 2008. "A global overview of pterosaur ichnology: tracksite distribution in space and time." Zitteliana. B28. p. 187-198. ISSN 1612 - 4138.
  24. ^ a b c d e f g Foster, J. (2007). "Comodactylus ostromi" Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. p. 159.
  25. ^ a b c d e f g Foster, J. (2007). "Dermodactylus montanus." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 158-159.
  26. ^ a b c d Foster, J. (2007). "Utahdactylus kateae." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. p. 160.
  27. ^ Czerkas, Stephen A.; and Mickelson, Debra L. (2002). "The first occurrence of skeletal pterosaur remains in Utah". in Czerkas, Sylvia J. (ed.). Feathered Dinosaurs and the Origin of Flight. Blanding, Utah: The Dinosaur Museum. pp. 3–13. ISBN 1-93207-501-1.  
  28. ^ Bennett, S. Christopher (2007). "Reassessment of Utahdactylus from the Jurassic Morrison Formation of Utah". Journal of Vertebrate Paleontology 27 (1): 257–260. doi:10.1671/0272-4634(2007)27[257:ROUFTJ]2.0.CO;2.  







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