Paleobiota of the Morrison Formation

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.

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.

(mostly from Foster [2003]; the higher-level classifications will vary as new finds are made.

Amphibians

A modern frog from the same family as Rhadinosteus parvus, the rhinophrynidae.

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]

In addition to formally named taxa, indeterminate anuran remains have been retrieved from Morrison strata in Colorado, Wyoming, and Utah, with the best specimens found in Dinosaur National Monument and Quarry 9.[1] Stratigraphically speaking, indeterminate anurans have been found in stratigraphic zones 2 and 4.[4] Indeterminate anurans with remains diagnostic down to the family level have also been reported from the Morrison. Pelobatids are represented by the illium of an unnamed, indeterminate species.[5] A specimen has been recovered from Quarry 9 of Como Bluff in Wyoming.[5] Pelobatids are present in stratigraphic zones 5 and 6.[4]

Indeterminate salamander remains are present in stratigraphic zones 2, 4, and 5.[4] A distinctive type of salamander known only as Caudata B is present in stratigraphic zone 6.[4]

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

Comobatrachus[1]

C. aenigmaticus

A dubious genus of prehistoric frog erected by O. C. Marsh to house fragmentary remains recovered from Reed's Quarry 9 near Como Bluff Wyoming.[1] Along with Eobatrachus it was among the earliest frog remains from the formation, although the two dubious genera were erected decades apart.[1]

Comonecturoides[6]

C. marshi[6]

Represented by a single femur.[6]

Considered a nomen dubium because the name is based on non-distinctive remains which cannot be classified in detail.[6]

Enneabatrachus[7]

E. hechti[2]

A small discoglossid frog whose live weight would have only been a few grams.[2]

Eobatrachus[1]

E. agilis

A dubious genus of prehistoric frog erected by O. C. Marsh to house fragmentary remains recovered from Reed's Quarry 9 near Como Bluff Wyoming.[1] Along with Comobatrachus it was among the earliest frog remains from the formation, although the two dubious genera were erected decades apart.[1]

Iridotriton[7]

I. hechti

A basal salamandroid closely related to today's advanced salamanders.

Rhadinosteus[7]

R. parvus[3]

  • Utah

Known from several slabs of rock which contain multiple partial specimens in association.[3]

A pipoid and possible rhinophrynid, Rhadinosteus parvus was only about 42 mm (1.6 inches) long in life.[3]

Arthropods

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

Eopolis

E. ekdalei

  • Utah
  • Brushy Basin

Nests produced by social insects.[9]

Morrisonnepa[10] M. jurassica
  • Utah
A hemipteran belonging to the group Nepomorpha.
Parapleurites[11] P. morrisonensis
  • Colorado
a forewing. a grasshopper.

Tektonargus

T. kollaspilus

  • Colorado
  • Brushy Basin

Five specimens were reported in the original description of the ichnogenus.

Choristoderes

Name Species State Member Material Notes

Cteniogenys[7]

C. antiquus

  • Colorado
  • Oklahoma
  • South Dakota
  • Utah
  • Wyoming

A champsosaur about 25 to 50 cm in length.

Crurotarsans

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 Diplosaurus ferox, Amphicotylus, Hoplosuchus kayi, and Macelognathus vagans.

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

Amphicotylus[12]

A. gilmorei

  • Wyoming

A. lucasii

  • Colorado

A. stovalli

  • Oklahoma

Diplosaurus[13]

D. felix

  • Colorado

Eutretauranosuchus[7]

E. delfsi

  • Colorado
  • Wyoming

Fruitachampsa[7]

F. callisoni

  • Colorado
  • Brushy Basin Member
  • Saltwash Member

Hallopus[7]

H. victor

  • Colorado

Hatcherichnus

H. sanjuanensis

  • Colorado
  • Utah

Indeterminate

  • Utah
  • Wyoming
  • Saltwash Member

Hoplosuchus[7]

H. kayi

  • Arizona
  • Utah

Macelognathus[7]

M. vagans

  • Colorado
  • Wyoming

Theriosuchus[14]

T. morrisonensis

  • Wyoming

A nearly complete left mandible missing teeth.

Dinosaurs

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.[15] Although abundant, fish remains are constrained to only certain locations within the formation.[15] Microvertebrate sites in Wyoming are dominated by fish remains.[15] Indeterminate ray-finned fish remains have been recovered from Ninemile Hill and a microvertebrate site in the Black Hills.[15] Found in stratigraphic zones 2, 4, and 5.[4] Morrison actinopterygians generally have no close modern relatives.[15] The Wyoming microvertebrate remains are extracted from the sediment by screenwashing.[15] Paleoniscoid remains are geographically present in the western part of Colorado, where remains have been recovered from "a level above the Mygatt-Moore Quarry."[15] Largely complete remains of small individuals have been consistently recovered for over 15 years.[15] So far, Morrison pycnodontoids are represented by a single specimen from Dinosaur National Monument in Utah.[16] Found in stratigraphic zone 4.[4] Only a single specimen from Dinosaur National Monument in Utah has been recovered.[16] 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.[16] A single tooth is the only known remains.[16] Dipnoan remains found at a fossil site not far from Cañon City, Colorado.[15] Remains usually in a state of rather complete preservation.[15] Halecostome remains are geographically present in the western part of Colorado, where remains have been recovered from "a level above the Mygatt-Moore Quarry."[15] Largely complete remains of small individuals have been consistently recovered for over 15 years.[15] Amiid remains found in stratigraphic zones 2, 3, and 4.[4] Found at a fossil site not far from Cañon City, Colorado.[15] Remains usually in a state of rather complete preservation.[15]

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

Ceratodus[7]

C. fossanovum[15]

A lungfish genus whose members ranged from 1 to 2 m in length and weights of up to 79 pounds, with most Morrison lungfish being on the smaller end of that range.[15] These species are believed to have had similar diets to extant lungfish like the physically similar modern genus Neoceratodus.[15]

C. ?frazieri[15]

C. guentheri[15]

C. robustus[15]

Indeterminate.

  • Brushy Basin
  • Saltwash

Represented by tooth plates.

Hulettia[7]

H. hawesi[17]

  • Colorado

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.

cf. Leptolepis[7]

N/A

Known only from a single nearly complete skeleton found at Rabbit Valley.[18] Found in stratigraphic zone 5.[4]

A 13 cm (5 inch) fish that was deeper bodied than its co-occurring contemporaries Morrolepis and Hulettia.[18] The Morrison cf. Leptolepis probably had a live mass of about 37g.[18] It is the only teleost fish known from the formation and was morphologically more highly derived than other Morrison fish.[18] It is believed to have fed on contemporary fish and small invertebrates.[18]

Morrolepis[7]

M. schaefferi[19]

  • Colorado

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.[19] Adult specimens would reach about 20 cm in length and 113 g (4 oz) in mass.[19]

Potamoceratodus

P. guentheri

  • Colorado

Once thought to be a species of Ceratodus.

Lizards and snakes

Name Species State Member Material Notes

Diablophis[20]

D. gilmorei

  • Colorado

A basal snake.[20] Originally described as a species of Parviraptor,[7] subsequently moved to its own genus.[20]

Dorsetisaurus[7]

  • Wyoming

An anguimorph lizard.

Paramacellodus[7]

  • Colorado
  • Wyoming

A small scincomorph lizard with blunt teeth.

Saurillodon[7]

Indeterminate

  • Colorado

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.[21]

Schillerosaurus[7][22]

S. utahensis[23]

  • Utah

A small scincomorph lizard of otherwise uncertain evolutionary affinities.[23] It is the only lizard genus endemic to the Morrison Formation.[23]

Mammaliaforms

Many types of mammaliaform cynodonts, mostly early mammals, are known from the Morrison; almost all of them were small sized animals, though occupying a very large variety of ecological niches, from the more rodent-like multituberculates to the carnivorous eutriconodonts (including the possibly volant Triconolestes) to the anteater-like Fruitafossor. 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, Glirodon grandis, Morrisonodon brentbaatar, Psalodon fortis, ?P. marshi, P. potens, and Zofiabaatar pulcher. Triconodonts present included Amphidon superstes, Aploconodon comoensis, Conodon gidleyi, Priacodon ferox, P. fruitaensis, P. gradaevus, P. lulli, P. robustus, Triconolestes curvicuspis, and Trioracodon bisulcus.

Tinodontids were represented by Eurylambia aequicrurius (probably Tinodon), and Tinodon bellus (including T. lepidus). Finally, two families of Dryolestoidea were present: Paurodontidae, including Comotherium richi, Euthlastus cordiformis, Paurodon valens, 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 mammaliaform 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.[24]

Tinodontids

Name Species State Member Material Notes

Eurylambia

E. aequicrurius

  • Wyoming

A tinodontid similar in appearance to Tinodon.

Tinodon[7]

T. bellus

  • Wyoming

Tinodontids.

T. lepidus

  • Wyoming

Eutriconodonts

Name Species State Member Material Notes

Amphidon[7]

A. superstes

  • Wyoming

A small amphidontid.

Aploconodon[7]

A. comoensis

  • Wyoming

An amphilestid eutriconodont.

Comodon[7]

C. gidleyi

  • Wyoming

An amphilestid eutriconodont slightly larger in size than Aploconodon.

Phascalodon

P. gidleyi

  • Wyoming

Triconolestes[7]

T. curvicuspis

  • Utah

A volaticotherian eutriconodont.

Trioracodon[7]

T. bisulcus

  • Wyoming

A triconodontid eutriconodont similar to Priacodon.

Multituberculates

Name Species State Member Material Notes

Ctenacodon[7]

C. laticeps

  • Wyoming

C. scindens

C. serratus

  • Wyoming

Glirodon[7]

G. grandis

  • Colorado
  • Utah

Morrisonodon

M. brentbaatar

  • Wyoming

Priacodon[7]

P. ferox

  • Wyoming

P. fruitaensis

  • Colorado

P. grandaevus

  • Wyoming

P. lulli

  • Wyoming

P. robustus

  • Wyoming

Psalodon[7]

P. fortis

P. marshi

P. potens

Zofiabaatar[7]

Z. pulcher

  • Wyoming

Others

Name Species State Member Material Notes

Docodon[7]

D. victor[25]

Fruitafossor[7]

F. windscheffeli

  • Colorado

Dryolestoids

Name Species State Member Material Notes

Amblotherium[7]

A. gracilis

  • Colorado

A small Dryolestid dryolestoid.

A. megistodon[26]

  • Wyoming

Araeodon[7]

A. intermissus

  • Utah
  • Wyoming

A paurodontid dryolestoid, somewhat smaller than Archaeotrigon and Paurodon. Considered to be a junior synonym of Paurodon valens by Averianov and Martin (2015).[27]

Archaeotrigon[7]

A. brevimaxillus

  • Wyoming

Paurodontid dryolestoids similar in appearance to Paurodon. Both species were considered to be junior synonyms of Paurodon valens by Averianov and Martin (2015).[27]

A. distagmus

Comotherium[7]

C. richi

  • Wyoming

A paurodontid dryolestoid.

Dryolestes[7]

D. obtusus

Dryolestid dryolestoids.

D. priscus

  • Wyoming

D. tenax

Euthlastus[7]

E. cordiformis

  • Wyoming

A paurodontid dryolestoid.

Foxraptor[7]

F. atrox

  • Wyoming

A paurodontid dryolestoid similar in size to Paurodon. Considered to be a junior synonym of Paurodon valens by Averianov and Martin (2015).[27]

Herpetairus

H.

Kepolestes

K.

  • Colorado

Laolestes[7]

L. eminens

Common Dryolestid dryolestoids.

L. grandis

Malthacolestes

M.

Melanodon

M.

Miccylotyrans

M. minimus

  • Morrison

A Dryolestid dryolestoid.

Paurodon[7]

P. valens

  • Wyoming

A paurodontid dryolestoid.

Pelicopsis

P. dubius

  • Wyoming

A paurodontid dryolestoid. Considered to be a junior synonym of Paurodon valens by Averianov and Martin (2015).[27]

Tathiodon[7]

T. agilis

  • Wyoming

A paurodontid dryolestoid.

Pterosaurs

Pterosaurs are very uncommon fossils in the Morrison, because the fragility of their thin walled bones often prevented their remains from being preserved.[28] Despite being uncommon they are geographically widespread;[29] 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).[28] Since the 1970s and 80s, pterosaur finds have become more common, but are still rare.[28] Most Morrison pterosaurs have been found in marine and shoreline deposits.[28] Pterosaur tracks have been found in both the Tidwell and Saltwash members.[28] Morrison pterosaurs probably lived on fish, insects and scavenged dinosaur carcasses, or even foraged for prey,and activally hunted;[28] they are fairly ecologically diverse, ranging from small hawking insectivore Mesadactylus to the raptorial Harpactognathus.

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

Comodactylus[7]

C. ostromi

  • Wyoming
  • Brushy Basin

1 specimen.

Nomen dubium

Dermodactylus[7]

D. montanus

  • Wyoming
  • Brushy Basin

1 specimen.

Nomen dubium

Harpactognathus[7]

H. gentryii

  • Wyoming
  • Brushy Basin

1 specimen.

A large rhamphorhynchoid with a wingspan of about 2.5 m and live mass of about 1.5 kg (3.3 lbs).[30] Harpactognathus was related to the Solnhofen genus Scaphognathus.[30]

Kepodactylus[7]

K. insperatus

  • Colorado
  • Brushy Basin

1 specimen.

A large pterodactyloid with a 2.5 m (8 foot) wingspan and a live weight of about 1.5 kg (3 lbs).[31] Kepodactylus may be related to the Asian dsungaripteroid pterosaurs.[31]

Laopteryx[29]

L. priscus

  • Wyoming
  • Brushy Basin

1 specimen.

Nomen dubium initially misidentified as a bird.

Mesadactylus[7]

M. ornithosphyos

  • Colorado
  • Brushy Basin

Pteraichnus[32]

P. saltwashensis'*

  • Arizona
  • Oklahoma
  • Saltwash

Utahdactylus[7]

U. kateae

  • Utah
  • Tidwell

1 specimen.

Nomen dubium. All that can be said for certain about its identity is that it is a diapsid reptile.

Sphenodonts

Name Species State Member Material Notes

Eilenodon[7]

E. robustus

  • Colorado

A sphenodontian of relatively large size.

Opisthias[7]

O. rarus

  • Colorado
  • Utah
  • Wyoming

A sphenodontian similar in appearance to the modern Tuatara

Theretairus[7]

T. antiquus

  • Wyoming

A small sphenodontian.

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.

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

Chelonipus

  • Colorado
  • Utah
  • Saltwash Member

Compsemys

C. plicatulus

  • Colorado

Dinochelys[7]

D. whitei

  • Colorado
  • Utah
  • Wyoming

Dorsetochelys[7]

D. buzzops

Glyptops[7]

G. plicatulus

  • Colorado
  • Wyoming

G. ornatus

  • Wyoming

G. utahensis

  • Utah

Uluops[7]

U. uluops

  • Wyoming

Insects

Insects are very rare in the Morrison Formation and only two have been described to date.

Name Species State Member Material Notes
Morrisonnepa[33] M. jurassica
  • Utah
A nepomorphan of uncertain placement

Parapleurites[34]

P. morrisonensis

  • Colorado

A Locustopsid orthopteran

See also

Footnotes

  1. Foster, J. (2007). "Anura (Frogs)." pp. 135-136.
  2. Foster, J. (2007). "Enneabatrachus hechti" p. 137.
  3. Foster, J. (2007). "Rhadinosteus parvus." p. 137.
  4. Foster, J. (2007). "Appendix." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 327-329.
  5. Foster, J. (2007). "Pelobatidae indet." p. 137.
  6. Foster, J. (2007). "Caudata (Salamanders)" p. 138.
  7. Foster, J. (2007). "Table 2.1: Fossil Vertebrates of the Morrison Formation." pp. 58-59.
  8. Foster, J. (2007). "Enneabatrachus hechti" p. 137. Note that Dinosaur National Monument is in Utah, see ibid. pg. 6.
  9. Elliott Armour Smith; Mark A. Loewen; James I. Kirkland (2020). "New social insect nests from the Upper Jurassic Morrison Formation of Utah". Geology of the Intermountain West. 7: 281–299.
  10. María B. Lara; John R. Foster; James I. Kirkland; Thomas F. Howells (2020). "First fossil true water bugs (Heteroptera, Nepomorpha) from Upper Jurassic strata of North America (Morrison Formation, southeastern Utah)". Historical Biology: An International Journal of Paleobiology. in press. doi:10.1080/08912963.2020.1755283.
  11. D. M. Smith, M. A. Gorman, J. D. Pardo and B. J. Small. 2011. First fossil Orthoptera from the Jurassic of North America. Journal of Paleontology 85(1):102-105
  12. Pritchard, A. C.; Turner, A. H.; Allen, E. R.; Norell, M. A. (2013). "Osteology of a North American Goniopholidid (Eutretauranosuchus delfsi) and Palate Evolution in Neosuchia". American Museum Novitates 3783 (3783): 1. doi:10.1206/3783.2. edit
  13. Allen, Eric Randall (Summer 2012). "Analysis of North American goniopholidid crocodyliforms in a phylogenetic context" (pdf). doi:10.17077/etd.317zy27t.
  14. Foster, J. (2018). "A new atoposaurid crocodylomorph from the Morrison Formation (Upper Jurassic) of Wyoming, USA". Geology of the Intermountain West. 5: 287–295. doi:10.31711/giw.v5i0.32. ISSN 2380-7601.
  15. Foster, J. (2007). "The Forgotten Aquatic Denizens: The Fish." pp. 129-131.
  16. Foster, J. (2007). "Pycnodontoidea." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. p. 135.
  17. Foster, J. (2007). "Hulettia hawesi." p. 132-134.
  18. Foster, J. (2007). "cf. Leptolepis." p. 135.
  19. Foster, J. (2007). "Morrolepis schaefferi." pp. 131-132.
  20. Caldwell, M. W.; Nydam, R. L.; Palci, A.; Apesteguía, S. N. (2015). "The oldest known snakes from the Middle Jurassic-Lower Cretaceous provide insights on snake evolution". Nature Communications. 6: 5996. doi:10.1038/ncomms6996. PMID 25625704.
  21. Foster, J. (2007). "Saurillodon sp." p. 145.
  22. Randall L. Lydam, Daniel J. Chure and Susan E. Evans (2013). "Schillerosaurus gen. nov., a replacement name for the lizard genus Schilleria Evans and Chure, 1999 a junior homonym of Schilleria Dahl, 1907" (PDF). Zootaxa. 3734 (1): 99–100. doi:10.11646/zootaxa.3736.1.6.
  23. Foster, J. (2007). "Schilleria utahensis" p. 145.
  24. Foster, J.R. 2009. Preliminary body mass estimates for mammalian genera of the Morrison Formation (Upper Jurassic, North America). PaleoBios 28(3):114-122.
  25. Julia A. Schultz; Bhart-Anjan S. Bhullar; Zhe-Xi Luo (2018). "Re-examination of the Jurassic mammaliaform Docodon victor by computed tomography and occlusal functional analysis". Journal of Mammalian Evolution. in press. doi:10.1007/s10914-017-9418-5.
  26. John R. Foster; Darrin C. Pagnac; ReBecca K. Hunt-Foster (2020). "An unusually diverse northern biota from the Morrison Formation (Upper Jurassic), Black Hills, Wyoming". Geology of the Intermountain West. 7: 29–67. doi:10.31711/giw.v7.pp29-67.
  27. A.O. Averianov and T. Martin (2015). "Ontogeny and taxonomy of Paurodon valens (Mammalia, Cladotheria) from the Upper Jurassic Morrison Formation of USA" (PDF). Proceedings of the Zoological Institute of the Russian Academy of Sciences. 319 (3): 326–340.
  28. Foster, J. (2007). "Soaring Overhead: The Pterosaurs." pp. 157-158.
  29. Foster, J. (2007). "Laopteryx priscus." p. 160.
  30. Foster, J. (2007). "Harpactognathus gentryii." p. 160.
  31. Foster, J. (2007). "Kepodactylus insperatus." p. 160.
  32. Lockley et al. (2008).
  33. Lara, María B.; Foster, John R.; Kirkland, James I.; Howells, Thomas F. (2020-05-18). "First fossil true water bugs (Heteroptera, Nepomorpha) from Upper Jurassic strata of North America (Morrison Formation, southeastern Utah)". Historical Biology: 1–9. doi:10.1080/08912963.2020.1755283. ISSN 0891-2963.
  34. Smith, Dena M.; Gorman, Mark A.; Pardo, Jason D.; Small, Bryan J. (January 2011). "First fossil orthoptera from the Jurassic of North America". Journal of Paleontology. 85 (1): 102–105. doi:10.1666/10-096.1. ISSN 0022-3360.

Bibliography

  • Foster, J. (2007). Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. 389pp. ISBN 978-0-253-34870-8
  • 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
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