Kirtland Formation

Geological formation in New Mexico and Colorado, United States

The Kirtland Formation (originally the Kirtland Shale) is a sedimentary geological formation.

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. 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. 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.

The formation was named by C. M. Bauer in 1916 for exposures near the Kirtland Post Office.

Saurischians of the Kirtland Formation Genus Species Member Material NotesImagesAlamosaurusA. sanjuanensisSpecimens actually from the Naashoibito member of the Ojo Alamo FormationAublysodonA. mirandus Hunter WashRemains are now referred to Bistahieversor, although these remains may possibly have come from the Fruitland Formation. BistahieversorB. sealeyi Hunter WashAn articulated skull and undescribed postcranial skeleton of an adult individual, and an incomplete skull and postcranial skeleton of a juvenile individual. A eutyrannosaur tyrannosauroid also known from the Fruitland Formation. CaenagnathidaeIndeterminateA partial skeleton, dentary, metatarsal, and numerous teeth. B. froeseorum[Two] incomplete skulls, an atlas, axis and cervical vertebrae. De na zinParasaurolophusP. tubicen De na zin[Two] incomplete and fragmentary skulls. A lambeosaurine hadrosaurid known from partial cranial remains. PentaceratopsP. fenestratusDe na zin MemberA crushed but nearly complete skull, mandible, cervical vertebrae, dorsal vertebrae, sacral vertebrae, caudal vertebrae, chevrons, scapulae, coracoids, radii, ulnae, ischia, ilia, pubes, femora, tibiae, astragali, manual phalanxes and manual unguals. A junior synonym of Pentaceratops sternbergii, diagnostic characteristics of the species were pathologies. P. sternbergi De na zinA crushed but nearly complete skull, mandible, cervical vertebrae, dorsal vertebrae, sacral vertebrae, caudal vertebrae, chevrons, scapulae, coracoids, radii, ulnae, ischia, ilia, pubes, femora, tibiae, astragali, manual phalanxes and manual unguals. A chasmosaurine ceratopsid also known from the Fruitland Formation. Sphaerotholus De na zin
Hunter Wash Hunter WashT. ouranosA partial skull, syncervical vertebrae, cervical vertebrae, dorsal vertebrae, sacral vertebrae, caudal vertebrae, ribs, humeri, radius, femora, tibiae, fibula, ilia, ischia, and ossified tendons. Possibly represents a junior synonym of Pentaceratops, holotype may possibly have come from the Fruitland Formation. ZiapeltaZ. sanjuanensis Hunter Wash
De na zin A complete skull, [two] first cervical half rings, fragmentary second cervical half ring, and numerous fragmentary osteoderms. An ankylosaurine ankylosaurid closely related to Scolosaurus.

Pterosaurs of the Kirtland Formation Genus Species Location Member Abundance NotesImagesNavajodactylusN. boerei Hunter Wash MemberPartial phalanx and ulna fragmentA possible azhdarchid pterosaur known from fragmentary remains.

Crurotarsans of the Kirtland Formation Genus Species Location Member Abundance Notes ImagesBrachychampsaB. montana De na zinMember of the Willow Wash local fauna. DenazinosuchusD. kirtlandicus De na zinMember of the Willow Wash local fauna. LeidyosuchusIndeterminate De na zinMember of the Willow Wash local fauna.

Turtles of the Kirtland Formation Genus Species Location Member Abundance NotesImagesBasilemysB. nobilis De na zinMember of the Willow Wash local fauna. DenazinemysD. nodosa De na zinMember of the Willow Wash local fauna. NeurankylusN. baueri De na zinMember of the Willow Wash local fauna. PlastomenusP. robustus De na zinMember of the Willow Wash local fauna. ThescelusT. hemispherica De na zinMember of the Willow Wash local fauna.

Bony fishes of the Kirtland Formation Genus Species Location Member Abundance NotesMelviusM. chauliodous De na zinMember of the Willow Wash local fauna.

Cartilaginous fish of the Kirtland Formation Genus Species Location Member Abundance NotesMyledaphusM. bipartitus De na zinMember of the Willow Wash local fauna.