| Cooper Canyon Formation | |
| Type: | Geological formation |
| Period: | Norian |
| Coordinates: | 33.127°N -101.366°W |
| Unitof: | Dockum Group |
| Overlies: | Camp Springs Formation, possibly Colorado City Formation |
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]
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.
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. 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).
| Temnospondyls of the Cooper Canyon Formation | ||||||
|---|---|---|---|---|---|---|
| Genus/Taxon | Species | Unit | Location | Material | Notes | Images |
| Apachesaurus | A. gregorii |
|
| Partial skull, mandible and pectoral girdle | The lowest known stratigraphic occurrence of diagnostic Apachesaurus cranial material. | |
| Buettnererpeton | B. bakeri[2] |
|
| Two skulls | A metoposaurid temnospondyl. Species was originally assigned to Anaschisma or Metoposaurus before being given its own genus in 2022.[3] | |
| Rileymillerus | R. cosgriffi |
|
| Skull and jaws, vertebral intercentra | An unusual small temnospondyl, known only by one specimen. | |
| Phytosaurs of the Cooper Canyon Formation | ||||||
|---|---|---|---|---|---|---|
| Genus/Taxon | Species | Unit | Location | Material | Notes | Images |
| Leptosuchus | L. sp.[4] |
|
| Partial skull and mandibles | May represent a distinct species of Leptosuchus from L. crosbiensis and L. studeri. | |
| Machaeroprosopus | M. lottorum[5] |
|
| Two skulls | A derived mystriosuchin phytosaur closely related to and intermediate with Redondasaurus. | |
| M. sp. |
|
| One skull | A specimen of Machaeoprosopus that appears phylogenetically distinct from M. lottorum. | ||
| M. sp. |
|
| Squamosal | The lowest occurrence of Machaeoprosopus in the Dockum Group, defining the base of the Revueltian teilzone in the Cooper Canyon Formation. | ||
| "Paleorhinus" | "P." cf. sawini |
|
| Skull | A phytosaur similar to "Paleorhinus" sawini, although potentially representing a distinct species. | |
| Redondasaurus? | R. gregorii? |
|
| Skull and postcranial skeleton (specimen TTUP 9425). | Specimens currently only described in unpublished theses, initially referred to a new informal genus "Macysuchus".[7] Referred to R. gregorii by Spielmann and Lucas (2012).[8] | |
Indeterminate paracrocodylomorph and stagonolepidid material is known from the Boren Quarry (MOTT 3869).
| Pseudosuchians of the Cooper Canyon Formation | ||||||
|---|---|---|---|---|---|---|
| Genus/Taxon | Species | Unit | Location | Material | Notes | Images |
| Calyptosuchus | C. wellesi |
|
| A desmatosuchian aetosaur. Material from Post Quarry named as the new genus and species Scutarx deltatylus in 2016.[9] | ||
| Crocodylomorpha indet. | Indeterminate |
|
| Femora | A small crocodylomorph comparable to Hesperosuchus. | |
| Desmatosuchus | D. smalli[10] |
|
| Several skulls and partial skeletons, osteoderms | 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. | |
| Garzapelta | G. muelleri[11] |
|
| Osteoderms and some associated postcrania | Believed to be a paratypothoracin aetosaur, but with lateral osteoderms convergent with desmatosuchins. | |
| Paratypothorax | P. sp. |
|
| Osteoderms and some associated postcrania | A paratypothoracin aetosaur. Potentially belongs to a distinct species from P. andressorum, as for other North American Paratypothorax. | |
| Poposaurus | P. gracilis |
|
| Femur, cervical vertebra | A bipedal predatory paracrocodylomorph. | |
| Postosuchus | P. kirkpatricki |
|
| Two skeletons and isolated remains | 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.[12] A fifth metatarsal from the Boren Quarry (MOTT 3869) may belong to Postosuchus.[13] | |
| Scutarx | S. deltatylus |
|
| Osteoderms | A desmatosuchine aetosaur based on material formerly assigned to Calyptosuchus wellesi. Known more abundantly in the Chinle Formation. | |
| Shuvosaurus | S. inexpectatus |
|
| Skulls and skeleton | 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? | S.? sp. |
|
| Lateral and caudal paramedian osteoderm | Aetosaur osteoderms compared favourably to Stagonolepis (including Calyptosuchus at the time). | |
| Typothorax | 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.[14]
| Ornithodirans of the Cooper Canyon Formation | ||||||
|---|---|---|---|---|---|---|
| Genus/Taxon | Species | Unit | Location | Material | Notes | Images |
|
| Material since referred to indeterminate herrerasaurids and neotheropods. | ||||
| Dinosauriformes indet. | Indeterminate |
|
| Two left fibulae | The fibulae are most similar to those of Marasuchus, but notably are three times as long. | |
| Dromomeron | D. gregorii |
|
| Four left femora | Lagerpetid pterosauromorphs. | |
| D. romeri[15] |
|
| Proximal right tibia | |||
| Herrerasauridae indet. | Indeterminate |
|
| Partial hip | Previously referred to Coelophysis bauri by Lehman and Chatterjee (2005).[16] | |
| Neotheropoda indet. | Indeterminate |
|
| Ilium and tibia | Previously referred to Coelophysis bauri by Lehman and Chatterjee (2005). | |
| Soumyasaurus | S. aenigmaticus[17] |
|
| Left dentary | A very small silesaurid dinosauriform, type specimen. | |
| Technosaurus | T. smalli |
|
| Premaxilla and dentary | A silesaurid dinosauriform, type and only specimen. | |
Fragmentary fossils are identifiable as archosauromorphs, namely members of the Allokotosauria+Prolacerta+Archosauriformes clade.[14]
| Non-crurotarsan archosauromorphs of the Cooper Canyon Formation | ||||||
|---|---|---|---|---|---|---|
| Genus/Taxon | Species | Unit | Location | Material | Notes | Images |
| cf. Doswellia | cf. D. sp. |
|
| Fragmentary osteoderm | An unusual armoured archosauriform. | |
| ?Malerisaurus | ?M. langstoni |
|
| Dentaries, cervical vertebrae, femur, humerus. | 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.[19] [20] | |
| Tanystropheidae indet. | Indeterminate |
|
| Two femora | Small tanystropheids comparable to Tanytrachelos and Langobardisaurus. | |
| Trilophosaurus | T. buettneri[21] |
|
| 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. T. jacobsi is also common at the Kahle Quarry (NMMNH L-3775) should it belong to the middle Cooper Canyon Formation. | |
| T. dornorum |
|
| Teeth, jaw elements[22] | |||
| T. jacobsi |
|
| Teeth | |||
| Vancleavea | V. campi |
|
| Postcervical vertebrae, osteoderms (MOTT 3624) | 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).
| Miscellaneous amniotes of the Cooper Canyon Formation | ||||||
|---|---|---|---|---|---|---|
| Genus/Taxon | Species | Unit | Location | Material | Notes | Image |
| Argodicynodon[23] | A. boreni |
|
| Skull, mandibles, and postcrania | A placeriine dicynodont, related to the later Placerias. | |
| Cf. Clevosaurus | Cf. C. sp. |
|
| Premaxilla | A sphenodontian lepidosauromorph, very similar to Clevosaurus. | |
| Dicynodontia indet. | Indeterminate |
|
| Cranial fragments, sternum. | Isolated indeterminate dicynodont material. | |
| Drepanosauromorpha indet. | Indeterminate |
|
| Two scapulacoracoids (MOTT 3624) | An unusual, possibly arboreal diapsid reptile. | |
| Eucynodontia indet. | Indeterminate |
|
| Jaw bones and teeth | Probable eucynodonts with teeth lacking a cingulum and possessing a large main cusp and 2–3 smaller posterior cusps. | |
| Kannemeyeriiformes indet. | Indeterminate |
|
| A humerus (MOTT 3881) and a femur (MOTT 3624). | Isolated indeterminate kannemeyeriiforms, potentially distinct from Argodicynodon. | |
| Libognathus[24] | L. sheddi |
|
| Skull and dentaries | A procolophonid parareptile, one of the only known from Late Triassic North America. | |
|
| Dentary with teeth | Named as a new species of Pachygenelus by Chatterjee (1983), assignment to this genus is doubtful. Material now provisionally regarded as eucynodont. | |||
| Protoavis | P. texensis |
|
| At least two partial skeletons | A problematic taxon purported to be an early avialan, may be a chimaera of different fossils.[25] | |
| Sphenodontia indet. | Indeterminate |
|
| Pterygoid and mandible | Sphenodont lepidosauromorphs. | |