Kirtland Formation
Geological formation in New Mexico and Colorado, United States
From Wikipedia, the free encyclopedia
The Kirtland Formation (originally the Kirtland Shale) is a sedimentary geological formation.[1]
| Kirtland Formation | |
|---|---|
| Stratigraphic range: Campanian (typically Kirtlandian) | |
Kirtland Formation at its type location south of Kirtland, New Mexico | |
| Type | Geological formation |
| Sub-units | Hunter Wash, Farmington and De-na-zin Members |
| Underlies | Ojo Alamo Formation |
| Overlies | Fruitland Formation |
| Thickness | 594 m (1,949 ft) |
| Lithology | |
| Primary | Sandstone |
| Other | Shale, mudstone, conglomerate |
| Location | |
| Coordinates | 36.708°N 108.350°W |
| Approximate paleocoordinates | 42.6°N 76.3°W |
| Region | New Mexico |
| Country | United States |
| Extent | San Juan Basin |
| Type section | |
| Named for | Kirtland Post Office |
| Named by | C.M. Bauer |
| Year defined | 1916 |
  Kirtland Formation (the United States)  Kirtland Formation (New Mexico) | |
Description
The Kirtland Formation is the product of alluvial muds and overbank sand deposits from the many channels draining the coastal plain that existed on the inland seashore of North America, in the late Cretaceous period. It overlies the Fruitland Formation. It is found in the San Juan Basin in the states of New Mexico and Colorado, in the United States of America.
The base of the Kirtland Formation and its lowest sub-unit, the Hunter Wash Member, has been dated to 75.02 ± 0.13 Ma.[2] Together with the upper part of the underlying Fruitland Formation, this contains fossils representing the Hunter Wash local fauna. The border between the Hunter Wash Member and overlying Farmington Member dates to approximately 74 million years ago. The top of the Farmington Member and bottom of the overlying De-na-zin Member has been radiometrically dated to 73.83 ± 0.18 Ma ago. The top of the De-na-zin Member, which contains the Willow Wash local fauna, has been dated to 73.49 ± 0.25 Ma ago.[1]
Overlying the De-na-zin Member is a unit called the Naashoibito Member. This has often been considered to be part of the Kirtland formation, but more recently has been transferred back to the overlying Ojo Alamo Formation, which it had originally been part of.[1]
History of investigation
The formation was named by C.M. Bauer in 1916 for exposures near the Kirtland Post Office.[3]
Stratigraphy
Vertebrate paleofauna
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Dinosaurs
Ornithischians
Ankylosaurids
| Ankylosaurids reported from the Kirtland Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Member | Material | Notes | Images | |
| A. minor[4] |
|
A partial girdle, scapulocoracoids, humerus, proximal portion of the radius, cervical and/or dorsal vertebrae, complete and fragmentary thoracic osteoderms, and other unidentifiable postcranial fragments.[4] | An ankylosaurine ankylosaurid part of the Hunter Wash Member.[4] |   | ||
| Nodocephalosaurus[5] | N. kirtlandensis[5] |
|
A partial skull.[5] | An ankylosaurine ankylosaurid that has cranial ornamentation similar to Akainacephalus, an ankylosaur from the Kaiparowits Formation.[5][6] | ||
| Z. sanjuanensis | A complete skull, [two] first cervical half-rings, fragmentary second cervical half ring, and numerous fragmentary osteoderms.[7] | An ankylosaurine ankylosaurid closely related to Scolosaurus. | ||||
Ceratopsians
| Ceratopsians reported from the Kirtland Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Member | Material | Notes | Images | |
| Bisticeratops[8] | B. froeseorum[8] |
|
A nearly complete skull.[8] | A chasmosaurine ceratopsid, originally identified as a specimen of Pentaceratops.[8] |      | |
| Navajoceratops[9] | N. sullivani[9] |
|
A parietal, squamosal fragments, fused jugal\epijugal and other unidentified cranial fragments.[9] | A chasmosaurine ceratopsid that has been hypothesized to form an anagenetic series with several other chasmosaur species, including Terminocavus.[9] | ||
| P. fenestratus[10] | A near-complete skull.[9] | Holotype considered undiagnostic. May be the same as Navajoceratops or Terminocavus.[9] | ||||
|
P. sternbergi[10] |
| |||||
| Terminocavus[9] | T. sealeyi[9] |
|
A parietal, partial squamosal, jugal, epijugal, partial quadratojugal, partial sacrum and vertebral fragments.[9] | A chasmosaurine ceratopsid that has been hypothesized to form an anagenetic series with several other chasmosaur species, including Navajoceratops.[9] | ||
| Titanoceratops[11] | T. ouranos[11] | A partial skull, syncervical vertebrae, cervical vertebrae, dorsal vertebrae, sacral vertebrae, caudal vertebrae, ribs, humeri, radius, femora, tibiae, fibula, ilia, ischia, and ossified tendons.[11] | Possibly represents a junior synonym of Pentaceratops, holotype may possibly have come from the Fruitland Formation.[11] | |||
Pachycephalosaurids
| Pachycephalosaurids reported from the Kirtland Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Member | Material | Notes | Images | |
| Sphaerotholus[12] | S. goodwini[12] |
|
A partial skull lacking the facial and palatal elements.[12] | A pachycephalosaurine pachycephalosaurid.[12] |   | |
| Stegoceras[13] | S. novomexicanum[13] |
|
An incomplete parietal.[13] | A basal pachycephalosaurid also known from the upper Fruitland Formation.[13] | ||
Ornithopods
| Ornithopods reported from the Kirtland Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Member | Material | Notes | Images | |
| A. wimani[14] |
|
A partial skull and mandible, three cervical vertebrae[14] | A kritosaurin hadrosaurid from the Hunter Wash Member. Several isolated bones and a partial skeleton from the same strata may also belong to this taxon[14] |     | ||
| A. horneri[15] |
|
An incomplete skull consisting of premaxillae, nasals, maxilla, lacrimal, jugal, prefrontal, postorbital, squamosal, frontal, parietal, and fragment of dentary with teeth.[15] | A kritosaurin hadrosaurid from the Farmington Member.[15] | |||
| Kritosaurus[15] | K. navajovius[15] |
|
[Two] incomplete skulls, an atlas, axis and cervical vertebrae.[15] | A kritosaurin hadrosaurid also known from the Cerro del Pueblo Formation of Mexico.[15] | ||
| Naashoibitosaurus[15] | N.ostromi[15] |
|
A skull lacking the premaxillae and mandible, a partial humerus, cervical vertebrae and dorsal vertebrae.[15] | A kritosaurin hadrosaurid, distinct from Kritosaurus.[15] | ||
| Parasaurolophus[16] | P. tubicen[16] |
|
[Two] incomplete and fragmentary skulls.[16] | A lambeosaurine hadrosaurid known from partial cranial remains.[16] | ||
| P. cyrtocristatus[16] |
|
Partial skull and nearly complete skeleton, partial juvenile skull.[16] | May instead be from the upper Fruitland Formation.[17] | |||
Saurischians
Sauropods
| Sauropods of the Kirtland Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Member | Material | Notes | Images |
|
A. sanjuanensis[18] |
Specimens actually from the Naashoibito member of the Ojo Alamo Formation[19] |  | |||
Theropods
| Theropods of the Kirtland Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Member | Material | Notes | Images |
|
A. mirandus[20] |
|
Remains are now referred to Bistahieversor, although these remains may possibly have come from the Fruitland Formation.[21] |
     | ||
| Bistahieversor[22] | B. sealeyi[22] |
|
An articulated skull and undescribed postcranial skeleton of an adult individual, and an incomplete skull and postcranial skeleton of a juvenile individual.[22] | A eutyrannosaur tyrannosauroid also known from the Fruitland Formation.[22] | |
| Caenagnathidae[23] | Indeterminate[23] |
|
A nearly complete right tibia[23] | Indeterminate caenagnathid remains.[23] | |
|
Indeterminate[20] |
|
Remains are now referred to Bistahieversor, although these remains may possibly have come from the Fruitland Formation.[21] | |||
| Dinevenator[24] | D. robustus[24] |
|
A nearly complete frontal[25] | Originally assigned to Saurornitholestes, subsequently recognized as a troodontid,[26] and tentatively assigned to the genus Xenovenator in early 2026.[27] Moved to its own genus later that year.[24] | |
| Dromaeosauridae[28] | Indeterminate[28] | Numerous isolated teeth.[28] | Indeterminate dromaeosaurid remains.[28] | ||
| Ornithomimidae[28] | Indeterminate[28] |
|
A distal end of a phalanx, and [two] partial manual unguals.[28] | Indeterminate ornithomimid remains.[28] | |
| Saurornitholestes[29] | S. sullivani[29] |
|
A nearly complete frontal.[29] | A saurornitholestine dromaeosaurid, sister taxa to Saurornitholestes langstoni.[29] | |
| Struthiomimus[28] | cf. S. altus[28] | A centrum of a dorsal vertebra, distal portion of a metatarsal, and proximal phalanx.[28] | Indeterminate remains that may belong to Struthiomimus altus.[28] | ||
| Tyrannosauridae[28] | Indeterminate[28] | A partial skeleton, dentary, metatarsal, and numerous teeth.[28] | Indeterminate tyrannosaurid material.[28] | ||
| cf. Tyrannosaurini[30] | Indeterminate[30] |
|
A left tibia.[30] | Indeterminate tyrannosaurin material.[30] | |
Pterosaurs
| Pterosaurs of the Kirtland Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Member | Abundance | Notes | Images |
|
N. boerei[31] |
|
Partial phalanx and ulna fragment[31] |
A possible azhdarchid pterosaur known from fragmentary remains.[31] |
|||
Crurotarsans
| Crurotarsans of the Kirtland Formation[32] | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Member | Abundance | Notes | Images |
|
B. montana |
|
Member of the Willow Wash local fauna. |
| |||
|
D. kirtlandicus |
|
Member of the Willow Wash local fauna. |
||||
|
Indeterminate[33] |
|
Member of the Willow Wash local fauna. |
||||
Turtles
| Turtles of the Kirtland Formation[32] | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Member | Abundance | Notes | Images |
|
B. nobilis |
|
Member of the Willow Wash local fauna. |
||||
|
D. nodosa |
|
Member of the Willow Wash local fauna. |
||||
|
N. baueri |
|
Member of the Willow Wash local fauna. |
||||
|
P. robustus |
|
Member of the Willow Wash local fauna. |
||||
|
Thescelus |
T. hemispherica |
|
Member of the Willow Wash local fauna. |
|||
Bony fish
| Bony fishes of the Kirtland Formation[32] | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Member | Abundance | Notes | |
|
M. chauliodous |
|
Member of the Willow Wash local fauna. | ||||
Cartilaginous fish
| Cartilaginous fish of the Kirtland Formation[32] | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Member | Abundance | Notes | |
|
M. bipartitus |
|
Member of the Willow Wash local fauna. | ||||
Color key
|
Notes Uncertain or tentative taxa are in small text; |