Cooper Canyon Formation | |
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Stratigraphic range: | |
Type | Geological formation |
Unit of | Dockum Group |
Overlies | Camp Springs Formation, possibly Colorado City Formation |
Location | |
Coordinates | 33°07′37″N101°21′58″W / 33.127°N 101.366°W |
Region | Texas |
Country | United States |
The Cooper Canyon Formation is a geological formation of Norian age in Texas. It is one of several formations encompassed by the Dockum Group. [1] [2]
The type area of the formation is situated in Garza County, Texas, southeast of Lubbock. The Cooper Canyon Formation consist of reddish siltstone and mudstone with lenses of sandstone and conglomerate. Thickness of the formation in the type area is 161.5 meters. It increases to the south, and in some places exceeds 200 m. The formation contains diverse fossils, including vertebrate remains. [2]
The Bull Canyon Formation in eastern New Mexico is equivalent to the upper part of the Cooper Canyon Formation. Some researchers argue that the latter name should be abandoned. [2] The middle and lower parts of the Cooper Canyon are correlated to the Trujillo and Tecovas formations (respectively) further north in the Texas Panhandle. The lowermost part of the Cooper Canyon Formation may also be correlated to the Colorado City Formation further south at Otis Chalk (Howard County). [3] [4] [5]
Color key
| Notes Uncertain or tentative taxa are in small text; |
Temnospondyls of the Cooper Canyon Formation | ||||||
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Genus/Taxon | Species | Unit | Location | Material | Notes | Images |
A. gregorii [4] |
|
| Partial skull, mandible and pectoral girdle [4] | The lowest known stratigraphic occurrence of diagnostic Apachesaurus cranial material. [6] | ||
B. bakeri [6] |
|
| Two skulls | A metoposaurid temnospondyl. Species was originally assigned to Anaschisma or Metoposaurus before being given its own genus in 2022. [3] [6] | ||
R. cosgriffi [4] |
|
| Skull and jaws, vertebral intercentra [4] | An unusual small temnospondyl, known only by one specimen. | ||
Phytosaurs of the Cooper Canyon Formation | ||||||
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Genus/Taxon | Species | Unit | Location | Material | Notes | Images |
L. sp. [4] |
|
| Partial skull and mandibles [4] | May represent a distinct species of Leptosuchus from L. crosbiensis and L. studeri. [4] | ||
M. lottorum [7] |
|
| Two skulls [7] | A derived mystriosuchin phytosaur closely related to and intermediate with Redondasaurus . [7] | ||
M. sp. |
|
| One skull [7] | A specimen of Machaeoprosopus that appears phylogenetically distinct from M. lottorum. [7] | ||
M. sp. [3] |
|
| Squamosal [3] | The lowest occurrence of Machaeoprosopus in the Dockum Group, defining the base of the Revueltian teilzone in the Cooper Canyon Formation. [3] [4] | ||
" Paleorhinus " | "P." cf. sawini [3] |
|
| Skull [3] | A phytosaur similar to "Paleorhinus" sawini, although potentially representing a distinct species. [3] | |
R. gregorii? [8] |
| Skull and postcranial skeleton (specimen TTUP 9425). [10] [8] | Specimens currently only described in unpublished theses, initially referred to a new informal genus "Macysuchus". [10] Referred to R. gregorii by Spielmann and Lucas (2012). [8] | |||
Indeterminate paracrocodylomorph and stagonolepidid material is known from the Boren Quarry (MOTT 3869). [11]
Pseudosuchians of the Cooper Canyon Formation | ||||||
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Genus/Taxon | Species | Unit | Location | Material | Notes | Images |
C. wellesi [11] |
|
| A desmatosuchian aetosaur. Material from Post Quarry named as the new genus and species Scutarx deltatylus in 2016. [12] | |||
Crocodylomorpha indet. [4] | Indeterminate |
| Femora [4] | A small crocodylomorph comparable to Hesperosuchus . [4] | ||
D. smalli [13] |
|
| Several skulls and partial skeletons, osteoderms [13] | An armoured aetosaur with large shoulder spines. Type locality of D. smalli, species also known from the Chinle Formation. Some skeletal postcranial material may belong to Paratypothorax. [12] | ||
G. muelleri [14] |
|
| Osteoderms and some associated postcrania [14] | Believed to be a paratypothoracin aetosaur, but with lateral osteoderms convergent with desmatosuchins. [14] | ||
P. sp. [12] |
|
| Osteoderms and some associated postcrania [4] | A paratypothoracin aetosaur. Potentially belongs to a distinct species from P. andressorum, as for other North American Paratypothorax. [12] | ||
P. gracilis [11] |
|
| Femur, cervical vertebra [15] | A bipedal predatory paracrocodylomorph. | ||
P. kirkpatricki [4] |
| Two skeletons and isolated remains [4] | A large predatory rauisuchid, type specimen from the Post Quarry. Most rauisuchid material from elsewhere in the southwestern US has also been assigned to Postosuchus kirkpatricki but it is unclear how much of it definitively belongs to Postosuchus. [16] A fifth metatarsal from the Boren Quarry (MOTT 3869) may belong to Postosuchus. [15] | |||
S. deltatylus [12] |
| Osteoderms [17] | A desmatosuchine aetosaur based on material formerly assigned to Calyptosuchus wellesi . Known more abundantly in the Chinle Formation. [12] | |||
S. inexpectatus [4] |
| Skulls and skeleton [4] | Originally named as an ornithomimid dinosaur based on its skull, later recognised to be synonymous with poposauroid postcrania named "Chatterjeea elegans". Type specimen is from the Post Quarry, Shuvosaurus has also reported from the Chinle Formation. | |||
Cf. Stagonolepis ? [3] | S.? sp. |
|
| Lateral and caudal paramedian osteoderm [3] | Aetosaur osteoderms compared favourably to Stagonolepis (including Calyptosuchus at the time). [3] | |
T. coccinarum |
| Partial skeleton, braincase, and osteoderms | A typothoracine aetosaur. Also commonly found in the Chinle Formation of Arizona and the Bull Canyon Formation of New Mexico. | |||
Numerous bones from ornithodirans have been discovered throughout the Cooper Canyon Formation but cannot be assigned to specific genera or clades. However, they are at least variably identifiable as lagerpetids, dinosauromorphs, dinosaurs, saurischians and theropods. [17]
Ornithodirans of the Cooper Canyon Formation | ||||||
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Genus/Taxon | Species | Unit | Location | Material | Notes | Images |
|
|
| Material since referred to indeterminate herrerasaurids and neotheropods. | |||
Dinosauriformes indet. [5] | Indeterminate |
|
| Two left fibulae [5] | The fibulae are most similar to those of Marasuchus , but notably are three times as long. [5] | |
D. gregorii [4] |
| |||||
D. romeri [5] |
|
| Proximal right tibia [5] | |||
Herrerasauridae indet. [4] | Indeterminate |
|
| Partial hip [4] | Previously referred to Coelophysis bauri by Lehman and Chatterjee (2005). [18] | |
Neotheropoda indet. [4] | Indeterminate |
|
| Previously referred to Coelophysis bauri by Lehman and Chatterjee (2005). [18] | ||
S. aenigmaticus [19] |
|
| A very small silesaurid dinosauriform, type specimen. [19] | |||
T. smalli [4] |
|
| Premaxilla and dentary [4] | A silesaurid dinosauriform, type and only specimen. | ||
Fragmentary fossils are identifiable as archosauromorphs, namely members of the Allokotosauria+ Prolacerta +Archosauriformes clade. [17]
Non-crurotarsan archosauromorphs of the Cooper Canyon Formation | ||||||
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Genus/Taxon | Species | Unit | Location | Material | Notes | Images |
cf. Doswellia [3] | cf. D. sp. |
|
| Fragmentary osteoderm [3] | An unusual armoured archosauriform. | |
?M. langstoni |
| A Malerisaurus-like taxon, a small carnivorous azendohsaurid allokotosaur. Three dentaries from the Boren Quarry were misinterpreted as the oldest saurischian dinosaurs in North America, but show affinity to malerisaurines. [21] [22] | ||||
Tanystropheidae indet. [17] | Indeterminate |
| Two femora [17] | Small tanystropheids comparable to Tanytrachelos and Langobardisaurus . [17] | ||
T. buettneri [23] |
|
| Teeth | Herbivorous trilophosaurid allokotosaurs. Of the three species represented in the Boren Quarry, T. dornorum and T. jacobsi are the more common, with T. buettneri represented by only two specimens. [3] T. jacobsi is also common at the Kahle Quarry (NMMNH L-3775) should it belong to the middle Cooper Canyon Formation. [23] | ||
| Teeth, jaw elements [24] | |||||
T. jacobsi [23] |
|
| Teeth | |||
V. campi [19] |
| Postcervical vertebrae, osteoderms (MOTT 3624) [19] | An unusual armoured semi-aquatic archosauriform. Additional limb bones from the Post and Kirkpatrick quarries may belong to Vancleavea or a related taxon. | |||
Numerous fragmentary limb bones of various reptiles have been collected that cannot be reliably diagnosed to specific clades, though some show similarities to drepanosauromorphs. Indeterminate procolophonid material is known from the Boren Quarry (MOTT 3869). [11]
Miscellaneous amniotes of the Cooper Canyon Formation | ||||||
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Genus/Taxon | Species | Unit | Location | Material | Notes | Image |
Argodicynodon [11] | A. boreni |
|
| A placeriine dicynodont, related to the later Placerias . [11] | ||
Cf. Clevosaurus [3] | Cf. C. sp. |
|
| Premaxilla [4] | A sphenodontian lepidosauromorph, very similar to Clevosaurus . | |
Dicynodontia indet. [3] [18] | Indeterminate |
| Cranial fragments, sternum. [11] | Isolated indeterminate dicynodont material. [11] | ||
Drepanosauromorpha indet. [4] | Indeterminate |
| Two scapulacoracoids (MOTT 3624) [4] | An unusual, possibly arboreal diapsid reptile. | ||
Eucynodontia indet. [4] | Indeterminate |
|
| Jaw bones and teeth [4] | Probable eucynodonts with teeth lacking a cingulum and possessing a large main cusp and 2–3 smaller posterior cusps. [4] | |
Kannemeyeriiformes indet. [11] | Indeterminate |
| Isolated indeterminate kannemeyeriiforms, potentially distinct from Argodicynodon. [11] | |||
L. sheddi [25] |
| A procolophonid parareptile, one of the only known from Late Triassic North America. [25] | ||||
|
|
| Dentary with teeth [4] | Named as a new species of Pachygenelus by Chatterjee (1983), assignment to this genus is doubtful. Material now provisionally regarded as eucynodont. [4] | ||
P. texensis [4] |
| At least two partial skeletons | A problematic taxon purported to be an early avialan, may be a chimaera of different fossils. [26] | |||
Sphenodontia indet. [3] | Indeterminate |
| Sphenodont lepidosauromorphs. | |||
Postosuchus, meaning "Crocodile from Post", is an extinct genus of rauisuchid reptiles comprising two species, P. kirkpatricki and P. alisonae, that lived in what is now North America during the Late Triassic. Postosuchus is a member of the clade Pseudosuchia, the lineage of archosaurs that includes modern crocodilians. Its name refers to Post Quarry, a place in Texas where many fossils of the type species, P. kirkpatricki, were found. It was one of the apex predators of its area during the Triassic, larger than the small dinosaur predators of its time. It was a hunter which probably preyed on large bulky herbivores like dicynodonts and many other creatures smaller than itself.
Gojirasaurus is a genus of "coelophysoid" theropod dinosaur from the Late Triassic of New Mexico. It is named after the giant monster movie character Godzilla, and contains a single species, Gojirasaurus quayi.
Shuvosaurus is a genus of beaked, bipedal poposauroid pseudosuchian from the Late Triassic of western Texas. Despite superficially resembling a theropod dinosaur, especially the ostrich-like ornithomimids, it is instead more closely related to living crocodilians than to dinosaurs. Shuvosaurus is known by the type and only species S. inexpectatus, and is closely related to the very similar Effigia within the clade Shuvosauridae. Shuvosaurus was originally described from a restored skull and very few fragmentary postcranial bones as a probable ornithomimosaur, or at least a very ornithomimosaur-like early theropod. The true pseudosuchian affinities of Shuvosaurus were only recognised after the discovery of Effigia linked the skull of Shuvosaurus with similar poposauroid skeletal remains found in the same quarry.
Spinosuchus is an extinct genus of trilophosaurid allokotosaur from the Late Triassic of Texas, southern United States. It has been assigned to a variety of groups over its history, from coelophysid dinosaur to pseudosuchian to uncertain theropod dinosaur and to Proterosuchidae. This uncertainty is not unusual, given that it was only known from a poorly preserved, wall-mounted, partial vertebral column of an animal that lived in a time of diverse, poorly known reptile groups. However, newly collected material and recent phylogenetic studies of early archosauromorphs suggest that it represents an advanced trilophosaurid very closely related to Trilophosaurus.
Aetosauroides is an extinct genus of aetosaur from the Late Triassic of South America. It is one of four aetosaurs known from South America, the others being Neoaetosauroides, Chilenosuchus and Aetobarbakinoides. Three species have been named: the type species A. scagliai, A. subsulcatus and A. inhamandensis. Fossils have been found in the Cancha de Bochas Member of the Ischigualasto Formation in the Ischigualasto-Villa Unión Basin in northwestern Argentina and the Santa Maria Formation in the Paraná Basin in southeastern Brazil. The strata date to the late Carnian and early Norian stages, making Aetosauroides one of the oldest aetosaurs.
Dromomeron is a genus of lagerpetid avemetatarsalian which lived around 220 to 211.9 ± 0.7 million years ago. The genus contains species known from Late Triassic-age rocks of the Southwestern United States and northwestern Argentina. It is described as most closely related to the earlier Lagerpeton of Argentina, but was found among remains of true dinosaurs like Chindesaurus, indicating that the first dinosaurs did not immediately replace related groups.
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Malerisaurus is an extinct genus of archosauromorph known from Telangana of India and Texas of the USA.
The Tecovas Formation is a geological formation in the Texas panhandle and eastern New Mexico. It is one of several formations encompassed by the Late Triassic Dockum Group.
Sterling Nesbitt is an American paleontologist best known for his work on the origin and early evolutionary patterns of archosaurs. He is currently an associate professor at Virginia Tech in the Department of Geosciences.
Leptosuchus is an extinct genus of leptosuchomorph phytosaur with a complex taxonomical history. Fossils have been found from the Dockum Group and lower Chinle Formation outcropping in Texas, New Mexico, and Arizona, United States, and date back to the Carnian stage of the Late Triassic.
Lucasuchus is an extinct genus of aetosaur. Fossils have been found from the Bull Canyon Formation of the Dockum Group outcropping in the Revuelto Creek locality in Quay County, New Mexico. All specimens date back to the Norian stage of the Late Triassic. The genus was named in 1995 after the American paleontologist Spencer G. Lucas.
Machaeroprosopus is an extinct genus of mystriosuchin leptosuchomorph phytosaur from the Late Triassic of the southwestern United States. M. validus, once thought to be the type species of Machaeroprosopus, was named in 1916 on the basis of three complete skulls from Chinle Formation, Arizona. The skulls have been lost since the 1950s, and a line drawing in the original 1916 description is the only visual record of the specimen. Another species, M. andersoni, was named in 1922 from New Mexico, and the species M. adamanensis, M. gregorii, M. lithodendrorum, M. tenuis, and M. zunii were named in 1930. Most species have been reassigned to the genera Smilosuchus, Rutiodon, or Phytosaurus. Until recently, M. validus was considered to be the only species that has not been reassigned. Thus, Machaeroprosopus was considered to be a nomen dubium or "doubtful name" because of the lack of diagnostic specimens that can support its distinction from other phytosaur genera. However, a taxonomic revision of Machaeroprosopus, conducted by Parker et al. in 2013, revealed that UW 3807, the holotype of M. validus, is not the holotype of Machaeroprosopus, while the species Machaeroprosopus buceros, Machaeroprosopus being a replacement name, with a fixed type species, for Metarhinus, is the combinatio nova of the type species of the genu: Belodon buceros. Therefore, the name Pseudopalatus must be considered a junior synonym of Machaeroprosopus, and all species of the former must be reassigned to the latter. This revised taxonomy was already accepted in several studies, including Stocker and Butler (2013). Stocker and Butler (2013) also treated M. andersoni as a valid species, and not a junior synonym of Machaeroprosopus buceros as was previously suggested by Long and Murry (1995).
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The Bull Canyon Formation is a geological formation of Late Triassic (Norian) age in eastern New Mexico and the Texas Panhandle. It is one of several formations encompassed by the Dockum Group.
The Colorado City Formation is a Late Triassic geologic formation in the Dockum Group of Texas, United States. It has previously been known as the Iatan Member, Colorado City Member or 'Pre-Tecovas Horizon'.
Scutarx is an extinct genus of Aetosauriformes, most commonly regarded by its species name Scutarx deltatylus. Scutarx lived around 230 million years ago during the Carnian and Norian stage of the Late Triassic. Scutarx are “medium sized” paramedian osteoderms belonging to the clade Aetosauria, a heavily armored and more herbivorous cousin of crocodiles.
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Soumyasaurus is a small silesaurid dinosauriform from the Late Triassic (Norian) Cooper Canyon Formation of western Texas.