The Chinle Formation is an extensive geological unit in the southwestern United States, preserving a very diverse fauna of Late Triassic (primarily Norian-age) animals and plants. This is a list of fossilized organisms recovered from the formation.
An archosauriform represented only by teeth.[1] It is treated as indeterminate archosauriform remains by Irmis in 2005.[1] It was originally thought to be an ornithischiandinosaur.
Moderately-sized tanystropheid vertebrae from the Hayden Quarry, likely representing a new taxon closely related to Langobardisaurus and Tanytrachelos.[7]
An unknown amniote represented by scattered teeth formerly believed to be from an ornithischian dinosaur.[9] Later discoveries of similar teeth in pseudosuchians meant that these could no longer be regarded as anything more specific than some kind of archosauriform.[9]
A strange neodiapsid whose bones were heavily ornamented "with subtriangular knobs... running the length of the bones." Even these ornamentations were ornamented "with additional grooves." It is too bizarre to be currently classified as anything more than a probable diapsid.[17]
A drepanosaur with a toothless skull and a flexible neck owing to the heterocoelous (saddle-shaped) articular surfaces of the vertebral centrae. The neural spines are anteroposteriorly short and strongly anterodorsally inclined. These features closely resemble those of Drepanosaurus.
A possible cynodont. Although they share some similarities with cynodont teeth, the teeth of Kraterokheirodon are very distinctive and can't be confidently referred to a known amniote group.[23]
A diapsid reptile of uncertain phylogenetic placement with unusual broadened teeth. More complete fossils of this genus from the Fremouw Formation of Antarctica suggest that it was an arboreal saurian.[25]
Known in Chinle from only a single tooth. The presence of venom channels is consistent with other known Uatchitodon specimens, although the Chinle specimen's channels are unique in being "completely enclosed under the surface of the crown."[30]
A reptile of unknown affinities, probably a carnivorous archosauromorph with venomous capabilities.
A. browni is "possibly the most common tetrapod fossil in the lower Chinle", although its presence in the upper Chinle is "unclear".[36]
A metoposauridtemnospondyl. Koskinonodon was erected for the species "Buettneria" perfecta when it was discovered that the latter genus was preoccupied. Gee et al., 2017 then synonymised it with Anaschisma.[34][35]
The crown of its tooth bears a "reticulating ornamentation on [its] occlusal surface[.]"[45]Reticulodus remains are common throughout the Norian microvertebrate sites of the American southwest.[45]
Arganodus toothplates are the most common fossil in the formation from a non-tetrapod.[50] They are evenly distributed across strata, although some individual localities have very high concentrations.[50]
Most Chinlean Arganodus fossils are isolated tooth plates.[50]
Isolated scales from Chinle microvertebrate sites commonly have Turseodus-like ridges, however that feature is not unique to Turseodus and in 2005 Irmis advised researchers to regard them as indeterminate palaeoniscid remains.[61]
Plants
The Chinle Formation has a diverse flora of plant megafossils, though they are concentrated in only a few sites with suitable conditions. One of the most diverse floral communities is found near Fort Wingate, New Mexico. Paleobotanists have traditionally placed the Fort Wingate plant beds into the Monitor Butte Member, though more recently they are placed within the Bluewater Creek Formation, a subunit of the Chinle Formation first defined in 1989.[62] Some Fort Wingate plant fossils belong to the "Lake Ciniza beds", a localized patch of grey mudstone corresponding to an ancient lake.[63]
Another productive areas for plant fossils is Petrified Forest National Park in Arizona. Though petrified wood could be found through the entire stratigraphy of the park, most other plant fossils are exclusive to greenish mudstone layers adjacent to the Newspaper Rock sandstone bed in the Blue Mesa Member (formerly known as the "Lower Petrified Forest").
The floral composition of the Chinle Formation (and other parts of Late Triassic North America) seem to shift with changes in climate over time. The lowest parts of the Chinle, such as the Shinarump Conglomerate, are dominated by the bennettitalean Eoginkgoites alongside the first occurrence of other persistent plants such as Phlebopteris, Equisetites, and most common conifer species. Subsequent subunits (such as the Blue Mesa Member, Monitor Butte Member, and Bluewater Creek Formation) are much more diverse, with a wide array of humidity-adapted plants making up the typical Chinle flora. This second floral zone is characterized by Dinophyton, a common but enigmatic shrubby gymnosperm. Plant fossils are rare in the upper part of the Chinle Formation, which was presumably much drier than the lower part. In these later layers, by far the most common plant fossils belong to Sanmiguelia (an endemic of southwestern North America) alongside conifers and horsetails.[66][67]
Bluewater Creek ("Ciniza Lake beds", formerly Monitor Butte)[63][72]
Common
An unusual gymnosperm combining needle-covered shoots with seed-bearing structures having the form of "pinwheel"-like clusters of tubular needles. Possibly related to Gnetales.
Fern-like gymnosperm leaves of uncertain affinities. Some leaves are affected by feeding traces including crescent-shaped marginal incisions and oval-shaped holes. These were probably produced by beetles or orthopterans (grasshoppers and kin).[80]
Bennettitalean leaves. Some leaves exhibit feeding traces, including sharp diagonal marginal traces and slot-like non-marginal traces. These traces were probably left by beetles.[80]Zamites powellii was formerly known as Otozamites powellii.
Bipinnate fern leaves previously identified as Lonchopteris. Some leaves are affected by crescent-shaped marginal feeding traces, probably from beetles or orthopterans (grasshoppers and kin).[80]
^ abcdef"Vertebrate Fauna; Archosauriformes; Crosbysaurus harrisae," Irmis (2005) p. 71
^ abWilliam G. Parker; Sterling J. Nesbitt; Adam D. Marsh; Ben T. Kligman; Kenneth Bader (2021). "First occurrence of Doswellia cf. D. kaltenbachi (Archosauriformes) from the Late Triassic (middle Norian) Chinle Formation of Arizona and its implications on proposed biostratigraphic correlations across North America during the Late Triassic". Journal of Vertebrate Paleontology. 41 (3): e1976196. doi:10.1080/02724634.2021.1976196. S2CID243474578.
^Brenen M. Wynd; Sterling J. Nesbitt; Michelle R. Stocker; Andrew B. Heckert (2020). "A detailed description of Rugarhynchos sixmilensis, gen. et comb. nov. (Archosauriformes, Proterochampsia), and cranial convergence in snout elongation across stem and crown archosaurs". Journal of Vertebrate Paleontology. 39 (6): e1748042. doi:10.1080/02724634.2019.1748042. S2CID219917329.
^ abcdefgh"Vertebrate Fauna; Temnospondyli; Buettneria perfecta" Irmis (2005) p. 67. Note that Koskinonodon was listed under the preoccupied (see Mueller 2007) name Buettneria in the preceding reference.
^ abcde"Vertebrate Fauna; Chondrichthyes; Acrodus sp." Irmis (2005) p. 65
^ abThe Petrified Forest and Sonsela Acrodus specimens are actually Reticulodus. See "Vertebrate Fauna; Chondrichthyes; Acrodus sp." Irmis (2005) p. 65 for details.
^ abcdef"Vertebrate Fauna; Chondrichthyes; Lonchidion humblei," Irmis (2005) p. 65
^ abcdefghijBobb Schaeffer (1967). "Late Triassic fishes from the western United States". Bulletin of the American Museum of Natural History. 135: 285β342. hdl:2246/1125.
^ abcSarah Z. Gibson (2013). "A new hump-backed ginglymodian fish (Neopterygii, Semionotiformes) from the Upper Triassic Chinle Formation of southeastern Utah". Journal of Vertebrate Paleontology. 33 (5): 1037β1050. doi:10.1080/02724634.2013.758125. S2CID129797885.
^Ben T. Kligman; William G. Parker; Adam D. Marsh (2017). "First record of Saurichthys (Actinopterygii) from the Upper Triassic (Chinle Formation, Norian) of western North America". Journal of Vertebrate Paleontology. 37 (5): e1367304. doi:10.1080/02724634.2017.1367304. S2CID134301176.
^Listed as "cf. Turseodus" in "Vertebrate Fauna; Osteichthyes; Cf. Turseodus sp." Irmis (2005) p. 66
^ abcdefghijklmnopqrstuvAsh, Sidney R. (1978). "4: Plant Megafossils". Geology, paleontology, and paleoecology of a Late Triassic lake, western New Mexico. Vol. 25. Brigham Young University Geology Studies.
^Kustatscher, Evelyn; Ash, Sidney R.; Karasev, Eugeny; Pott, Christian; Vajda, Vivi; Yu, Jianxin; McLoughlin, Stephen (2018), Tanner, Lawrence H. (ed.), "Flora of the Late Triassic"(PDF), The Late Triassic World, Topics in Geobiology, vol. 46, Cham: Springer International Publishing, pp. 545β622, doi:10.1007/978-3-319-68009-5_13, ISBN978-3-319-68008-8, retrieved 2022-11-21
^Lucas, Spencer G. (2013). "Plant megafossil biostratigraphy and biochronology, Upper Triassic Chinle Group, Western USA". New Mexico Museum of Natural History and Science Bulletin. 61: 354β365.
^ abcdefghijklmnopqrAsh, Sidney R. (1987). "The Upper Triassic Red Bed Flora of the Colorado Plateau, Western United States". Journal of the Arizona-Nevada Academy of Science. 22 (1): 95β105. JSTOR40024387.
^ abcdefAsh, Sidney R. (1973). "Two New Late Triassic Plants from the Petrified Forest of Arizona". Journal of Paleontology. 47 (1): 46β53. JSTOR1302865.
^ abcAsh, Sidney R. (1970). "Pagiophyllum simpsonii, a New Conifer from the Chinle Formation (Upper Triassic) of Arizona". Journal of Paleontology. 44 (5): 945β952. JSTOR1302730.
^ abAsh, Sidney R. (1982). "Occurrence of the Controversial Plant Fossil Sanmiguelia cf. S. lewisi Brown in the Upper Triassic of Utah". Journal of Paleontology. 56 (3): 751β754. JSTOR1304404.
^ abcdefghiMilner, Andrew C. (2006). "Plant fossils from the Owl Rock or Church Rock members, Chinle Formation, San Juan County, Utah". New Mexico Museum of Natural History & Science Bulletin. 37: 410β413.
Irmis, R. B. 2005. The vertebrate fauna of the Upper Triassic Chinle Formation in northern Arizona. p. 63-88. in S.J. Nesbitt, W.G. Parker, and R.B. Irmis (eds.) 2005. Guidebook to the Triassic formations of the Colorado Plateau in northern Arizona: Geology, Paleontology, and History. Mesa Southwest Museum Bulletin 9.
Mueller, B. D. and Parker, W. G. 2006. A new species of Trilophosaurus (Diapsida: Archosauromorpha) from the Sonsela Member (Chinle Formation) of Petrified Forest National Park, Arizona. In W. G. Parker, S. R. Ash & R. B. Irmis (eds.), A Century of Research at Petrified Forest National Park, 1906-2006: Geology and Paleontology. Museum of Northern Arizona Bulletin 62:119-125
Mueller, B.D. (2007). "Koskinonodon Branson and Mehl, 1929, a replacement name for the preoccupied temnospondyl Buettneria Case, 1922". Journal of Vertebrate Paleontology. 27 (1): 225. doi:10.1671/0272-4634(2007)27[225:KBAMAR]2.0.CO;2. S2CID85763026.
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