TheKayenta Formation is ageological formation in theGlen Canyon Group that is spread across theColorado Plateau area of theUnited States, including northernArizona, northwestColorado,Nevada, andUtah. Originally suggested as beingSinemurian-Pliensbachian, but more recentdating of detrital zircons has yielded a depositional age of 183.7 ± 2.7 Ma, thus a Pliensbachian-Toarcian age is more likely.[2] A previous depth work recovered a solid "Carixian" (Lower-Middle Pliensbachian) age from measurements done in theTenney Canyon.[3] More recent works have provided varied datations for the layers, with samples from Colorado and Arizona suggesting 197.0±1.5-195.2±5.5 Ma (Middle Sinemurian), while the topmost section is likely Toarcian or close in age, maybe even recovering terrestrial deposits coeval with theToarcian Oceanic Anoxic Event.[4] This last age assignation also correlated the Toarcian Vulcanism on the westCordilleran Magmatic Arc, as the number of grains from this event correlate with the silt content in the sandstones of the upper layers.[4]
The Kayenta Formation frequently appears as a thinner dark broken layer belowNavajo Sandstone and aboveWingate Sandstone (all three formations are in the same group). Together, these three formations can result in immense vertical cliffs of 600 metres (2,000 ft) or more. Kayenta layers are typically red to brown in color, forming broken ledges.
In most sections that include all threegeologic formations of theGlen Canyon group the Kayenta is easily recognized. Even at a distance it appears as a dark-red, maroon, or lavender band of thin-bedded material between two thick, massive, cross beddedstrata of buff, tan, or light-red color. Its position is also generally marked by a topographic break. Its weak beds form a bench or platform developed by stripping the Navajo sandstone back from the face of the Wingate cliffs. The Kayenta is made up of beds of sandstone,shale, and limestone, alllenticular, uneven at their tops, and discontinuous within short distances. They suggest deposits made by shiftingstreams of fluctuating volume. The sandstone beds, from less than 25 millimetres (1 in) to more than 3 metres (10 ft) thick, are composed of relatively coarse, well-roundedquartz grains cemented bylime andiron. The thicker beds are indefinitely cross bedded. The shales are essentiallyfine-grained, very thin sandstones that include limeconcretions and balls of consolidatedmud. The limestone appears as solid gray-blue beds, a few inches to a few feet thick, and as lenses of limestoneconglomerate. Most of the limestone lenses are less than 8 metres (25 ft) long, but two were traced for nearly 150 metres (500 ft) and one for 500 metres (1,650 ft).
Viewed as a whole, the Kayenta is readily distinguished from the geologic formations above and below it. It is unlike them in composition, color, manner of bedding, and sedimentary history. Obviously the conditions of sedimentation changed in passing from the Wingate Sandstone formation to the Kayenta and from the Kayenta to the Navajo sandstone, but the nature and regional significance of the changes have not been determined. In some measured sections the transition from Wingate to Kayenta is gradual; the material in the basal Kayenta, beds seems to have been derived from the Wingate immediately below and redeposited with only the discordance characteristic of fluviatile sediments. But in many sections the contact between the two formations is unconformable; the basal Kayenta consists of conglomerate and lenticular sandstone that fills depressions eroded in the underlying beds. InMoqui Canyon near Red Cone Spring nearly 3 metres (10 ft) of Kayenta limestone conglomerate rests in a long meanderingvalley cut in Wingate. Likewise, the contact between the Kayenta and the Navajo in places seems to be gradational, but generally a thin jumbled mass of sandstone and shales, chunks of shale and limestone, mud balls, and concretions of lime and iron, lies at the base of the fine-grained, cross bedded Navajo. Mud cracks, a fewripple marks, and incipient drainage channels were observed in the topmost bed of the Kayenta onRed Rock Plateau; and in west Glen Canyon, wide sand-filled cracks appear at the horizon. These features indicate that, in places at least, the Wingate and Kayenta were exposed toerosion before their overlying geologic formations were deposited, are it may be that the range in thickness of the Kayenta thus in part (is) accounted for.
The red and mauve Kayentasiltstones andsandstones that form the slopes at base of theNavajo Sandstone cliffs record the record of low to moderate energy streams. Poole (1997) has shown that the streams still flowed toward the east depositing from 150 to 210 m (500 to 700 ft) ofsediment here. Thesedimentary structures showing the channel andflood plain deposits ofstreams are well exposed on switchbacks below the tunnel in Pine Creek Canyon.
In the southeastern part of Zion National Park a stratum ofcross beddedsandstone is found roughly halfway between the top and bottom of the Kayenta Formation. It is a "tongue" of sandstone that merges with the Navajo formation east ofKanab, and it shows thatdesert conditions occurred briefly in this area during Kayenta time. This tongue is the ledge that shades the lower portion of the Emerald Pool Trail, and it is properly called Navajo, not Kayenta.
These vary in size, but all seem to be the tracks of three-toedreptiles that walked upright, leaving their tracks in the muds on the flood plains. Unfortunately, so far no bone materials have been found in Washington County that would enable more specific identification.
Apparently during Kayenta time Zion was situated in a climatic belt like that ofSenegal with rainy summers and dry winters at the southern edge of a great desert. The influence of thedesert was about to predominate, however, asNorth America drifted northward into the arid desert belt.
The Kayenta Formation is approximately 120 metres (400 ft) thick and consists of a fine-grained sandstone interbedded with layers of siltstone. The alternation of these units generally produces a series of ledges and slopes between the cliffs of the Navajo andMoenave formation. Dinosaur tracks are fairly common in the siltstone, andfresh watermussels andsnails occur but are rare. The Kayenta Formation is colored pale red and adds to the splendor of theVermilion Cliffs. It accumulated as deposits of rivers.
A freshwater (lacustrine or fluvial) ostracod, type member of the familyDarwinulidae. Kayenta specimens have a distinctive columnar calcitic layer. The Kayenta fauna is similar to the Sinemurian faunas of theToutunhe Formation of Xinjiang, China.
A freshwater (lacustrine or fluvial) snail, incertae sedis insideMesogastropoda. Differs considerably from the species from the Upper JurassicMorrison Formation,Liratina jurassicum
A freshwater (lacustrine or fluvial) ostracod, incertae sedis insideCypridacea. Differs from all other described species of the genus in being more elongate and from most in being spinose.
The "Kayenta Fish Fauna" is the last one recovered from the Glen Canyon Group sequence and it is delimited mostly to the silty facies of the Lower-Middle Part of the formation.[8] This Fauna is rather scarce and delimited to several concrete locations with proper lacustrine or fluvial deposition, and are also scarce due topreservation bias.[8] Another aspect that can explain the lack of fish fossils found is the use of different research techniques than used on theChinle Formation.[8]
UCMP 136104, 136105 + ten uncatalogued specimens, teeth
A freshwater (lacustrine or fluvial) non-neoselachian shark, incertae sedis insideHybodontoidea. The remains of sharks are rather rare on the formation and limited to several locations with typical lacustrine or fluvial floodplain deposition.
A freshwater (lacustrine or fluvial)toarcibatid. Related originally withMicropristis orLibanopristis, and stated to be reworked from younger Cretaceous deposits, was found due to its asymmetrical cusp to fit within the definition ofToarcibatis, being more likely to be native of the formation.[10]
Large (1 m) Complete specimen; Isolated Ganoid Scales & Teeth
A freshwater (lacustrine or fluvial)semionotidsemionotiform, probably related to the genusSemionotus. Semionotiformes are the only properly identified bony fishes from the formation, including a large specimen exposed at the Dan O'Laurie Museum.[8]
Semionotus is probably related to the Kayenta Seminotiformes
A freshwater (lacustrine or fluvial)ceratodontiddipnomorph (lungfish). Was described asC. felchi, know from the Upper JurassicMorrison Formation. Other dipnoan specimens have been cited but never described.[14]
An Advanced Sphenodont, member ofSphenodontinae. The skeleton ofN. sani shows a large number of similarities with the modern tuataraS. punctatus, clustering them closely together in the morphospace of sphenodontians and early lepidosaurs.[18]
UCMP 125871: Skull with mandibles and one epibranchial lacking the dorsal part of the braincase, articulated with the atlas, axis, and 2 cervical vertebrae.
UCMP 125358
UCMP 125359: An eroded compressed braincase.
UCMP 125872: A right jugal and maxilla in articulation in a large block of unprepared material.
UCMP 125870: A very well-preserved braincase
UCMP 130082
Early terrestrial or semi-terrestrial herbivorous Crocodylomorphs. Includes two taxa similar to theCretaceousEdentosuchus tienshanensis, one that has been referred to informally as "Gomphosuchus" (including UCMP 97638 and UCMP 125871) and another unnamed taxon (including UCMP 130082).[25] Previously considered one taxon (the 'Kayenta form') in older literature.[26]
Indeterminate ornithischian remains located in Arizona, USA.[27] Ornithischian tracks located in Arizona, USA.[27] Indeterminate theropod remains located in Arizona, US.[27] Theropod tracks located in Arizona and Utah, US.[27] Possible theropod tracks located in Arizona, Colorado, and Utah, US.[27]
MCZ 9092, complete upper and lower dentitions, many other portions of the skull, vertebrae from all portions of the axial column, and portions of fore and hind girdles and limbs[28]
A heterodontosaurid of uncertain placement. Appears to have been an insectivore downsized to a degree not seen before among early dinosaurs.
A uncertain placement large ornithischian and teeth from diverse type of genera. The femur was assigned toDilophosaurus wetherilli.[30] The femur resembles that of the early neornithischianLesothosaurus.[31]
An advanced neotheropod, type member of the familyDilophosauridae.Dilophosaurus is the main identified dinosaur from the formation, being both the most known and studied. It was among the largest theropods present locally, and very likely an active hunter, rather than a fisher.[42]
A pterosaur, considered a member of the familyDimorphodontidae. Was originally classified as a "rhamphorhynchoid", represents the only major pterosaur identified from the formation and one of the oldest from North America.
Burrow-like ichnofossils. It is referred to vermiform deposit-feeders. It is controversial, since is considered a strictly a junior synonym ofPalaeophycus.[65]
Burrow-like ichnofossils. Ichnofossils done by organisms advancing along the bottom surface. Very narrow, vertical or subvertical, slightly winding unlined shafts filled with mud. Interpreted as dwelling structures of vermiform animals, more concretely theDomichnion of a suspension-feeding Worm orPhoronidan, with certainSkolithos representing entrance shafts to more complicated burrows.
Skolithos ichnofosil reconstruction, with possible fauna associated
Saltwater/Blackish burrow-like ichnofossils.Taenidium is a meniscate backfill structure, usually considered to be produced by an animal progressing axially through the sediment and depositing alternating packets of differently constituted sediment behind it as it moves forward.
^Weishampel, David B; et al. (2004). "Dinosaur distribution (Early Jurassic, North America)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.):The Dinosauria, 2nd, Berkeley: University of California Press. pp. 530–532.ISBN0-520-24209-2.
^abMarsh, Adam Douglas (2018). "Contextualizing the evolution of theropod dinosaurs in western North America using U-Pb geochronology of the Chinle Formation and Kayenta Formation on the Colorado Plateau".UT Electronic Theses and Dissertations.doi:10.26153/tsw/41876 (inactive 1 July 2025).{{cite journal}}: CS1 maint: DOI inactive as of July 2025 (link)
^abcKietzke, K.K.; Lucas, S.G. (1995). "Ostracoda and Gastropoda from the Kayenta Formation (Lower Jurassic) of Arizona, U.S.A".Journal of Arizona–Nevada Academy of Science.28 (1–2):23–32.JSTOR40024298.
^abMilner, A. R. C.; Birthisel, T. A.; Kirkland, J. I.; Breithaupt, B.H; Matthews, N. A.; Lockley, M. G.; Santucci, V. L.; Gibson, S. Z; DeBlieux, D. D.; Hurlbut, M.; Harris, J. D.; Olsen, P. E. (2011). "Tracking Early jurassic dinosaurs across southwestern Utah and the Triassic-Jurassic transition".Nevada State Museum Paleontological Papers.1 (1):1–107.
^abcdefghijklmnMilner, A. R.; Gay, R. J.; Irmis, R.; Overkamp, F.; Santella, M. (2017). "New southwestern Utah paleontological locality from the Lower Jurassic Kayenta Formation reveals a diverse vertebrate fauna based on teeth and tracks [abs.]".Journal of Vertebrate Paleontology.37 (1): 164.
^abcMilner, A. R.; Kirkland, J. I. (2006). "Preliminary review of the early Jurassic (Hettangian) freshwater Lake Dixie fish fauna in the Whitmore Point Member, Moenave Formation in southwest Utah".New Mexico Museum of Natural History and Science Bulletin.37 (1–2):510–521.CiteSeerX10.1.1.537.1492.
^abcdefghWeishampel, David B; et al. (2004). "Dinosaur distribution (Early Jurassic, North America)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.):The Dinosauria, 2nd, Berkeley: University of California Press. pp. 530–32.ISBN0-520-24209-2.
^DeVries, R.P.; Sereno, P.C. (2024). "Tiny dinosaur from the Kayenta Formation (Early Jurassic: Pliensbachian) of northern Arizona implicates dwarfing and insectivory at the base of the heterodontosaurid radiation".SVP 84th ANNUAL MEETING.84.
^abBreeden, Benjamin T. (2018). "Fragmentary specimens provide evidence for hidden taxonomic diversity of ornithischian dinosaurs within the Lower Jurassic Kayenta Formation (northeastern Arizona, USA)".SVP 2018.1 (1): 96.
^Tykoski, R.S. (1997). "A new ceratosaurid theropod from the Early Jurassic Kayenta Formation of Northern Arizona".Journal of Vertebrate Paleontology.17 (3):81–82.
^Bristowe, A.; M.A. Raath (2004). "A juvenile coelophysoid skull from the Early Jurassic of Zimbabwe, and the synonymy ofCoelophysis andSyntarsus.(USA)".Palaeontologica Africana.40 (40):31–41.
^abWellnhofer, Peter (1991).Summary of Lower Jurassic Pterosaurs. The Illustrated Encyclopedia of Pterosaurs (1 ed.). London: Salamander Books Limited. p. 79.ISBN0-86101-566-5.
^abHans-Dieter, Sues; Jenkins, F. A. (2006). "The Postcranial Skeleton of Kayentatherium Wellesi from the Lower Jurassic Kayenta Formation of Arizona and the Phylogenetic Significance of Postcranial Features in Tritylodontid Cynodonts".Carrano, Matthew T., Gaudin, T. J., Blob, R. W. And Wible, J. R.: Amniote Paleobiology. Perspectivers on the Evolution of Mammals, Birds, and Reptiles the University of Chicago Press.1 (1):114–52.
^abMilner, A.R.C.; Birthisel, T. A.; Kirkland, J. I.; Breithaupt, B.H.; Matthews, N. A.; Lockley, M. G.; Santucci, V. L.; Gibson, S. Z.; DeBlieux, D. D.; Hurlbut, M.; Harris, J. D.; Olsen, P. E. (2011). "Tracking Early jurassic dinosaurs across southwestern Utah and the Triassic-Jurassic transition".Nevada State Museum Paleontological Papers.1 (1):1–107.
^abcMiller, W. E.; Britt, B. B.; Stadtman, K. L. (1986). "Theropod and prosauropod trackways from the Moenave Formation of southwestern Utah".In D. D. Gillette (Ed.), First International Symposium on Dinosaur Tracks and Traces, Abstracts with Program.21 (2):36–48.
^abWelles, S. P. (1971). "Dinosaur footprints from the Kayenta Formation of northern Arizona".Plateau.44 (1):27–38.
^Stokes, W. L.; Bruhn, A. F. (1960). "Dinosaur tracks from Zion National Park and Vicinity, Utah".Utah Academy Proceedings.37 (2):75–76.
^Barnes, F. A. (1997). "Canyon Country Dinosaur".Tracks and Trackers.54 (1):1–176.
^abcHamblin, A. H.; Lockley, M.G.; Milner, A.R.C. (2006). "More reports of theropod dinosaur tracksites from the Kayenta Formation (Lower Jurassic), Washington County, Utah: implications for describing the Springdale megatracksite".New Mexico Museum of Natural History and Science Bulletin.37 (3):276–281.
^Hamblin, A. H. (2006).Spectrum Tracksite—also known as the Grapevine Pass Wash Tracksite. California State University: Desert Studies Consortium and LSA Associates.
^Lockley, M. G.; Hunt, A. P.; Meyer, C. A.; Rainforth, E. C.; Schultz, R. J. (1998). "A survey of fossil footprint sites at Glen Canyon National Recreation Area (western USA): a case study in documentation of trace fossil resources at a national preserve".Ichnos.5 (3):177–211.Bibcode:1998Ichno...5..177L.doi:10.1080/10420949809386417.
^Hamblin, A. H.; Foster, J. R. (2001). "Ancient animal footprints and traces in the Grand Staircase-Escalante National Monument, south-central Utah".Utah Geological Association Publication.28 (4):1–12.
Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.):The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. ISBN0-520-24209-2.
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