Paleobiota of the Chinle Formation
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.
Amniotes
Crurotarsans
Other Archosauromorphs
Non-crurotarsan Archosauromorphs of the Chinle Formation | ||||||
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Genus | Species | State | Member | Abundance | Notes | Images |
C. harrisae[1] |
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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 ornithischian dinosaur. |
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Doswellia[2] | cf. D. kaltenbachi |
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Osteoderms, vertebrae, rib and hip fragments. | A doswelliid archosauriform. | |
Puercosuchus[3] | P. traverorum |
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Two monodominant bonebeds. |
A carnivorous azendohsaurid archosauromorph. | |
Rugarhynchos[4] | R. sixmilensis |
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Skull and postcranial fragments. | A doswelliid archosauriform. Originally described as a species of Doswellia,[5] but subsequently transferred to a separate genus. | |
Syntomiprosopus[6] | S. sucherorum |
|
Two to four individuals from a single quarry.[6] |
A short-faced archosauriform, possibly an unusual early-diverging crocodylomorph. Appears convergent with some Late Cretaceous notosuchians.[6] | ||
Tanystropheidae[7] | Indeterminate |
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Vertebrae | Moderately-sized tanystropheid vertebrae from the Hayden Quarry, likely representing a new taxon closely related to Langobardisaurus and Tanytrachelos.[7] | |
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A small tanystropheid represented by several hundred fossil specimens. | ||||
T. murryi[9] |
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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] | |||
T. buettneri[11] |
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T. dornorum[12] |
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T. jacobsi[13] |
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T. phasmalophos[14] |
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V. campi[15] |
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A strange aquatic carnivorous archosauriform, represented by both articulated skeletons and scattered elements like osteoderms and vertebrae.[15] | |||
Other amniotes
Miscellaneous amniotes of the Chinle Formation | ||||||
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Genus | Species | State | Member | Abundance | Notes | Images |
A. rectori[17] |
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Known only from a partial skull.[17] |
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] |
| ||
Ancistronychus[18] | A. paradoxus |
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Manual unguals (hand claws). | A drepanosaur related to Drepanosaurus. | |
Avicranium[19] | A. renestoi |
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Skull and neck vertebrae. | 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. | |
C. obscurus[20] |
|
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Known only from a jaw fragment and some isolated teeth.[20] |
Originally believed to be a fish, Colognathus was a strange amniote with distinctive fluted teeth.[20] | ||
Dolabrosaurus | D. aquatilis |
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Articulated vertebral and limb material. | A drepanosaur. | |
Drepanosaurus[21] | D. unguicaudatus |
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A drepanosaur. | ||
K. venetus |
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Partial dentaries. |
A non-mammalian eucynodont. | ||
K. colberti[23] |
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Known only from two teeth.[23] |
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] | |||
Palacrodon[24] | Indeterminate |
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Jaw fragments. | 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] | |
P. hesternus[26] |
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Known from several hundred remains, but very rare outside of the highly concentrated Placerias Quarry.[26] |
A placeriine stahleckeriid dicynodont. | |||
Skybalonyx[27] | S. skapter |
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Manual unguals (hand claws). | A drepanosaur which likely had a burrowing lifestyle. | |
U. schneideri[29] |
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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. | ||
Whitakersaurus[31] | W. bermani |
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A rhynchocephalian found at Ghost Ranch. | ||
Indeterminate procolophonid[32] | Indeterminate |
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Amphibians
Color key
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Notes Uncertain or tentative taxa are in small text; |
Amphibians of the Chinle Formation | ||||||
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Genus | Species | State | Member | Abundance | Notes | Images |
A. gregorii[33] |
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Common in the Owl Rock and Petrified forest members.[33] Blue Mesa remains are fragmentary.[33] |
A metoposaurid temnospondyl which is a junior synonym of Anaschisma |
| |
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A. browni is "possibly the most common tetrapod fossil in the lower Chinle", although its presence in the upper Chinle is "unclear".[36] |
A metoposaurid temnospondyl. 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] | ||||
C. jenkinsi |
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A temnospondyl in the group Stereospondyli, related to Rileymillerus from the Dockum Group of Texas. Possibly a stem-caecilian according to one analysis,[37] though others have disputed this finding | ||||
Funcusvermis[38] | F. gilmorei |
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Numerous jaw fragments, as well as a referred maxillopalatine, vertebra, and femur | A stem-caecilian | |
Indeterminate |
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A stem-group frog. Might be more closely related to crown-group frogs (anurans) than to Early Triassic taxa Triadobatrachus and Czatkobatrachus. | |||
Cartilaginous fish
Chondrichthyans of the Chinle Formation | ||||||
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Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
Indeterminate[40] |
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Only a single tooth is known.[40] |
A hybodontiform shark. | ||
L. humblei[42] |
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A hybodontiform shark. Lonchidion remains are common throughout the Carnian microvertebrate sites of the American southwest.[42] | ||||
Palaeoxyris | P. humblei[43] |
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Several specimens | An egg capsule of a freshwater hybodont shark. | |
Indeterminate[44] |
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Only a single specimen has been recovered from the formation.[44] |
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Reticulodus[45] |
R. synergus[45] |
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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] | |||
X. moorei[46] |
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Common in the lower Chinle Formation's microvertebrate localities.[46] |
A xenacanthiform shark. | |||
Lobe-finned fish
Coelacanths
Actinistians (coelacanths) of the Chinle Formation | ||||||
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Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
Indeterminate[48] |
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An actinisitan (coelacanth). |
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Lungfish
Color key
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Notes Uncertain or tentative taxa are in small text; |
Dipnoans (lungfish) of the Chinle Formation | ||||||
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Genus | Species | State | Stratigraphic position | Abundance | Notes | |
A. dorotheae[49] |
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Indeterminate[49] |
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Arganodus toothplates are the most common fossil in the formation from a non-tetrapod.[49] They are evenly distributed across strata, although some individual localities have very high concentrations.[49] |
Most Chinlean Arganodus fossils are isolated tooth plates.[49] | |||
C. dorotheae[49] |
Named by Case in 1921, in the 1980s it was referred to Arganodus.[49] | |||||
Ray-finned fish
Actinopterygians (ray-finned fish) of the Chinle Formation | ||||||
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Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
Indeterminate[51] |
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Known only from two vertebrae.[51] |
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Cionichthys[52] |
C. dunklei |
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A member of Redfieldiiformes. | |||
H. weiri |
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A member of Dapediiformes.[53] | |||
L. hillsi[52] |
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A member of Redfieldiiformes. | ||||
Indeterminate[55] |
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Represented by isolated scales.[55] | ||||
Lophionotus[56] |
L. sanjuanensis[56] |
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A member of Semionotiformes. | ||
L. chinleana[57] |
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A member of Semionotiformes. | |||
Indeterminate |
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A member of Saurichthyiformes. | |||
Synorichthys[52] |
S. stewarti |
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A member of Redfieldiiformes. | |||
Tanaocrossus[52] |
T. kalliokoskii |
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An enigmatic actinopterygian.[53] | |||
T. dolorensis[52] |
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A member of Palaeonisciformes.[52] | ||||
Indeterminate[60] |
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Common.[60] |
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.[60] | |||
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.[61] Some Fort Wingate plant fossils belong to the "Lake Ciniza beds", a localized patch of grey mudstone corresponding to an ancient lake.[62]
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").
Conifers are the most common and diverse plants, including petrified wood and leafy branches from massive trees (Araucarioxylon, Pagiophyllum) as well as smaller shrubby forms (Pelourdea). Cycad and bennettitalean leaves and other remains make up a significant portion of the flora (Zamites, Nilssoniopteris, Williamsonia, etc.). Ferns (Cladophlebis, Phlebopteris, Clathropteris, Cynepteris, etc.) are abundant, with a range of growth habits including low shrubs, tree ferns, and palm-like fronds comparable to their modern relatives. Sphenophytes (horsetails: Neocalamites, Equistetites, Schizoneura, etc.) have low diversity but high abundance, and the largest Neocalamites fossils in the Chinle Formation could reach up to 6 meters (20 feet) in height. "Seed ferns" (Chilbinia, Marcouia?) ginkgophytes (Baiera), and small lycopods (Chinlea, Selaginella) were present but uncommon. The flora is rounded out by unusual low-growing gymnosperms such as Sanmiguelia (an angiosperm-like shrub), Dechellyia, and Dinophyton (possible relatives of Gnetales).[63][64]
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.[65][66]
Gymnosperms
Gymnosperms of the Chinle Formation | ||||||
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Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
Araucariorhiza[67] | A. joae | Uncommon | Roots of conifers similar to modern Araucariaceae. Possibly from the same plant as Araucarioxylon arizonicum. | |||
A. arizonicum, A. sp.[69] |
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Abundant | Petrified trunks of large conifers possibly related to modern Araucariaceae.[72] State fossil of Arizona. | |||
Araucarites | A. rudicula[73] |
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Very rare | Large female conifer cones similar to those of araucariacean conifers. | |
Aricycas[74] | A. paulae |
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Moderately common | Pinnate cycad leaves | |
Baiera | B. arizonica | Uncommon | Ginkgophyte leaves | |||
Brachyphyllum | B. sp,
B. hegewaldia[76] |
Uncommon | Conifer leaves and shoots | |||
Carpolithus | C. chinleana |
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Rare | Seeds of uncertain affinities | ||
Cephalotaxopsis | C. sp. |
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Conifer foliage | |||
Charmorgia | C. dijolli |
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Rare | Short cycad stems | |
Chilbinia[77] | C. lichii |
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Rare | An archaic seed fern with seeds and leaves more similar to Carboniferous-Permian seed ferns than to Triassic forms. | |
Creberanthus | C. bealeii[73] |
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Very rare | Pollen-bearing cones similar to those of some extinct "pteridosperms" (seed ferns). Associated with Alisporites opii, a common palynomorph. | ||
Dadoxylon | D. chaneyi |
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Very rare | Possible cordaitalean conifer wood. | |
Dechellyia[78] | D. gormanii | Uncommon | An enigmatic gymnosperm with narrow pinnate leaves, "clasping" leaf-like sporophylls, and winged seeds. Some leaves are affected by galls, similar to those formed by eriophyid mites in modern plants.[79][80] | |||
Dinophyton | D. spinosus[81] | 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. | |||
Elatocladus | E. puercoensis[80] |
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Uncommon | Leaf-bearing conifer shoots | |
Eoginkgoites | E. sp.,
E. davidsonii[82] |
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Common within its small stratigraphic range | A bennettitalean with palm-shaped fronds similar to some ginkgo species. | ||
Ginkgoites | G. sp. |
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Rare | A ginkgophyte | |
Lindleycladus | L. arizonicus[80] |
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Uncommon | Conifer shoots bearing Podozamites leaves. Formerly known as Podozamites arizonicus. | |
Lyssoxylon | L. grigsbyi | Rare | Cycad trunks | |||
Marcouia | M. neuropteroides | Uncommon | 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).[79] | |||
Masculostrobus | M. clathratus[78] |
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Locally common | A pollen-bearing cone associated with lattice-shaped Equisetosporites chinleana pollen. | |
Nilssoniopteris | N. ciniza[62][71] | Uncommon | Large smooth-edged bennettitalean leaves, some of which were originally identified as Macrotaeniopteris magnifola. | |||
Otozamites | O. macombii |
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Uncommon | Bennettitalean leaves | |
Pagiophyllum | P. sp.,
P. duttonia,[62] P. navajoensis,[62] P. readiana,[62] P. zuniana,[62] P. simpsonii[83] |
Locally very common | Conifer leaves | |||
Palissya | P. sp.,
P. diffusa, P. sphenolepis |
Uncommon | Conifer leaves and shoots | |||
Pelourdea | P. poleoensis | Common | A shrubby conifer with strap-like leaves arranged around a single narrow stem. | |||
Podozamites | P. sp.,
P. emmonsi, P. lanceolatus |
Uncommon | Conifer leafs and shoots | |||
Pramelreuthia | P. dubielli,[84] P. yazzi[84] |
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Rare | Gymnosperm microsporophylls (pollen-bearing organs) | |
Pterophyllum | P. sp.,
P. braunianum |
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Uncommon | Bennettitalean leaves | ||
Samaropsis | S. sp.,
S. puerca |
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Uncommon | Seeds of uncertain affinities | ||
Sanmiguelia | S. lewisii | Common | An unusual palm-like shrub, controversially suggested to be a relative or predecessor of angiosperms (flowering plants). | |||
Schilderia |
S. adamanica |
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Rare | Petrified stems of a conifer or gnetalean[72] | ||
Williamsonia | W. nizhonii[87] | Rare | A bennettitalean "flower" (female cone) | |||
Woodworthia |
W. arizonica |
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Uncommon |
Stems and petrified wood of a conifer related to A. arizonicum.[72][88] |
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Zamites | Z. sp.,
Z. occidentalis, Z. powellii |
Very common | 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.[79] Zamites powellii was formerly known as Otozamites powellii. | |||
Ferns
Ferns of the Chinle Formation | ||||||
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Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
Apachea | A. arizonica |
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Rare | Dipteridacean fern leaves, possibly damaged specimens of Clathropteris walkeri.[91] | |
Cladophlebis | C. daughertyi,[91] C. subfalcata,
C. yazzia,[76] C. sp. |
Very common | Large sterile fern leaves of uncertain affinities | |||
Clathropteris | C. walkeri | Common | Dipteridacean fern leaves | |||
Cynepteris[91] | C. sp.,
C. lasiophora[91] |
Common | 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).[79] | |||
Itopsidema[92] | I. vancleavi |
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Uncommon | Stems of large osmundacean tree ferns. Some stems show evidence of being bored by oribatid mites.[93] | |
Phlebopteris | P. smithii,
P. utensis |
Common | Matoniacean fern leaves with a palmate structure | |||
Sphenopteris | S. arizonica | Uncommon | Sterile fern leaves of uncertain affinities. Some show evidence for marginal damage by insect feeding traces.[95] | |||
Todites | T. fragilis | Uncommon | Osmundacean fern leaves | |||
Wingatea[91] | W. plumosa | Rare | Gleicheniacean fern leaves previously named as a species of Coniopteris. |
Other plants
Other plants of the Chinle Formation | ||||||
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Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
Chinlea | C. sp.,
C. campii |
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Uncommon | Small lycopod stems similar to shrubby forms such as Pleuromeia.[96] | ||
Equisetites | E. sp.,
E. bradyi |
Common | A horsetail indistinguishable from modern Equisetum. | |||
Equisetocalis[97] | E. muirii |
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Concentrated in a narrow stratigraphic range (the Newspaper Rock sandstone bed) | Small three-dimensional horsetail stems preserved in pyrite nodules. | |
Isoetites | I. circularis |
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Rare | Quillwort shoots | |
Lycostrobus | L. chinleana |
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Rare | Horsetail cones sometimes placed in the genus Equicalostrobus | ||
Neocalamites | N. sp.,
N. virginiensis |
Common | Stems and leaves of a giant sphenophyte (horsetail) | |||
Schizoneura | S. harrisii |
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Uncommon | Stems and leaves of a large sphenophyte (horsetail) more typical of Southern Hemisphere plant assemblages. | |
Selaginella | S. anasazia[78] |
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Uncommon | A low-growing lycopsid similar to modern broad-leaved species of Selaginella, such as S. kraussiana |
Arthropods
Arthropods of the Chinle Formation | ||||||
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Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
Enoplocytia | E. porteri[99] |
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Single well-preserved fossil | An erymid crayfish | |
Paleoscolytus[100] |
P. divergus |
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A species of bark beetle, evidenced by trace fossils of tracks made on A. arizonicum specimens. |
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- "Vertebrate Fauna; Parareptilia; Colognathus obscurus," Irmis (2005) p. 69
- Pritchard, Adam C.; Turner, Alan H.; Irmis, Randall B.; Nesbitt, Sterling J.; Smith, Nathan D. (2016-10-24). "Extreme Modification of the Tetrapod Forelimb in a Triassic Diapsid Reptile". Current Biology. 26 (20): 2779–2786. doi:10.1016/j.cub.2016.07.084. ISSN 0960-9822. PMID 27693141.
- Ben T. Kligman; Adam D. Marsh; Hans-Dieter Sues; Christian A. Sidor (2020). "A new non-mammalian eucynodont from the Chinle Formation (Triassic: Norian), and implications for the early Mesozoic equatorial cynodont record". Biology Letters. 16 (11): Article ID 20200631. doi:10.1098/rsbl.2020.0631. PMC 7728676. PMID 33142088.
- "Vertebrate Fauna; Amniota incertae sedis; Kraterokheirodon colberti," Irmis (2005) p. 69
- Ben T. Kligman; Adam D. Marsh; William G. Parker (2018). "First records of diapsid Palacrodon from the Norian, Late Triassic Chinle Formation of Arizona, and their biogeographic implications". Acta Palaeontologica Polonica. 63 (1): 117–127. doi:10.4202/app.00426.2017.
- Jenkins, Kelsey M.; Meyer, Dalton L.; Lewis, Patrick J.; Choiniere, Jonah N.; Bhullar, Bhart-Anjan S. (2022). "Re-description of the early Triassic diapsid Palacrodon from the lower Fremouw formation of Antarctica". Journal of Anatomy. 241 (6): 1441–1458. doi:10.1111/joa.13770. PMC 9644968. PMID 36168715. S2CID 252565757.
- "Vertebrate Fauna; Synapsida; Placerias hesternus," Irmis (2005) p. 82
- Xavier A. Jenkins; Adam C. Pritchard; Adam D. Marsh; Ben T. Kligman; Christian A. Sidor; Kaye E. Reed (2020). "Using manual ungual morphology to predict substrate use in the Drepanosauromorpha and the description of a new species". Journal of Vertebrate Paleontology. 40 (5): e1810058. doi:10.1080/02724634.2020.1810058.
- Listed as cf. Uatchitodon sp. in "Vertebrate Fauna; Reptilia incertae sedis; Cf. Uatchitodon sp," Irmis (2005) p. 69
- Mitchell, Jonathan S.; Heckert, Andrew B.; Sues, Hans-Dieter (2010). "Grooves to tubes: evolution of the venom delivery system in a Late Triassic "reptile"". Naturwissenschaften. 97 (12): 1117–1121. Bibcode:2010NW.....97.1117M. doi:10.1007/s00114-010-0729-0. PMID 21060984. S2CID 10093308.
- "Vertebrate Fauna; Reptilia incertae sedis; Cf. Uatchitodon sp," Irmis (2005) p. 69
- Heckert, Andrew B.; Lucas, Spencer G.; Rinehart, Larry F.; Hunt, Adrian P. (2008-07-01). "A New Genus and Species of Sphenodontian from the Ghost Ranch Coelophysis Quarry (upper Triassic: Apachean), Rock Point Formation, New Mexico, Usa". Palaeontology. 51 (4): 827–845. doi:10.1111/j.1475-4983.2008.00786.x. ISSN 1475-4983.
- Nicholas C. Fraser; Randall B. Irmis; David K. Elliott (2005). "A procolophonid (Parareptilia) from the Owl Rock Member, Chinle Formation of Utah, USA". Palaeontologia Electronica. 8 (1): Article Number 8.1.13.
- "Vertebrate Fauna; Temnospondyli; Apachesaurus gregorii" Irmis (2005) pp. 67-68
- Mueller (2007)
- Gee, Bryan M.; Parker, William G.; Marsh, Adam D. (2020). "Redescription of Anaschisma (Temnospondyli: Metoposauridae) from the Late Triassic of Wyoming and the phylogeny of the Metoposauridae". Journal of Systematic Palaeontology. 18 (3): 233–258. doi:10.1080/14772019.2019.1602855. S2CID 190896742.
- "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.
- Jason D. Pardo; Bryan J. Small; Adam K. Huttenlocker (2017). "Stem caecilian from the Triassic of Colorado sheds light on the origins of Lissamphibia". Proceedings of the National Academy of Sciences of the United States of America. 114 (27): E5389–E5395. Bibcode:2017PNAS..114E5389P. doi:10.1073/pnas.1706752114. PMC 5502650. PMID 28630337.
- Kligman, Ben T.; Gee, Bryan M.; Marsh, Adam D.; Nesbitt, Sterling J.; Smith, Matthew E.; Parker, William G.; Stocker, Michelle R. (2023-01-25). "Triassic stem caecilian supports dissorophoid origin of living amphibians". Nature. 614 (7946): 102–107. doi:10.1038/s41586-022-05646-5. hdl:10919/113568. ISSN 1476-4687. PMC 9892002. PMID 36697827. S2CID 256272986.
- Michelle R. Stocker; Sterling J. Nesbitt; Ben T. Kligman; Daniel J. Paluh; Adam D. Marsh; David C. Blackburn; William G. Parker (2019). "The earliest equatorial record of frogs from the Late Triassic of Arizona". Biology Letters. 15 (2): Article ID 20180922. doi:10.1098/rsbl.2018.0922. hdl:10919/87931. PMC 6405462. PMID 30958136.
- "Vertebrate Fauna; Chondrichthyes; Acrodus sp." Irmis (2005) p. 65
- The Petrified Forest and Sonsela Acrodus specimens are actually Reticulodus. See "Vertebrate Fauna; Chondrichthyes; Acrodus sp." Irmis (2005) p. 65 for details.
- "Vertebrate Fauna; Chondrichthyes; Lonchidion humblei," Irmis (2005) p. 65
- Fischer, Jan; Axsmith, Brian J.; Ash, Sidney R. (2010-03-01). "First unequivocal record of the hybodont shark egg capsule Palaeoxyris in the Mesozoic of North America". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 255 (3): 327–344. doi:10.1127/0077-7749/2009/0028. ISSN 0077-7749.
- "Vertebrate Fauna; Chondrichthyes; Phoebodus sp." Irmis (2005) p. 65
- "Vertebrate Fauna; Chondrichthyes; Reticulodus synergus," Irmis (2005) p. 65
- "Vertebrate Fauna; Chondrichthyes; 'Xenacanthus' moorei," Irmis (2005) p. 64
- Listed as cf. Chinlea sp. in "Vertebrate Fauna; Temnospondyli; Cf. Chinlea sp." Irmis (2005) p. 67
- "Vertebrate Fauna; Temnospondyli; Cf. Chinlea sp." Irmis (2005) p. 67
- "Vertebrate Fauna; Temnospondyli; Arganodus sp." Irmis (2005) p. 67
- Listed as "cf. Australosomus" in "Vertebrate Fauna; Osteichthyes; Cf. Australosomus sp." Irmis (2005) p. 66-67
- "Vertebrate Fauna; Osteichthyes; Cf. Australosomus sp." Irmis (2005) p. 66-67
- Bobb Schaeffer (1967). "Late Triassic fishes from the western United States". Bulletin of the American Museum of Natural History. 135: 285–342. hdl:2246/1125.
- Sarah Z. Gibson (2016). "Redescription and Phylogenetic Placement of †Hemicalypterus weiri Schaeffer, 1967 (Actinopterygii, Neopterygii) from the Triassic Chinle Formation, Southwestern United States: New Insights into Morphology, Ecological Niche, and Phylogeny". PLOS ONE. 11 (9): e0163657. Bibcode:2016PLoSO..1163657G. doi:10.1371/journal.pone.0163657. PMC 5033578. PMID 27657923.
- Listed as "cf. Lasalichthyes" in "Vertebrate Fauna; Osteichthyes; Cf. Lasalichthyes sp." Irmis (2005) p. 66
- "Vertebrate Fauna; Osteichthyes; Cf. Lasalichthyes sp." Irmis (2005) p. 66
- Sarah 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): 1037–1050. doi:10.1080/02724634.2013.758125. S2CID 129797885.
- Sarah Z. Gibson (2013). "Biodiversity and Evolutionary History of †Lophionotus (Neopterygii: †Semionotiformes) from the Western United States". Copeia. 2013 (4): 582–603. doi:10.1643/CI-12-028. S2CID 85755730.
- 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. S2CID 134301176.
- Listed as "cf. Turseodus" in "Vertebrate Fauna; Osteichthyes; Cf. Turseodus sp." Irmis (2005) p. 66
- "Vertebrate Fauna; Osteichthyes; Cf. Turseodus sp." Irmis (2005) p. 66
- Lucas, S.G.; Hayden, S.N. (1989). "Triassic stratigraphy of west-central New Mexico" (PDF). New Mexico Geological Society Field Conference Guidebook. 40: 191–211.
- Ash, 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.
- Ash, Sidney R. (1989). "A catalog of Upper Triassic plant megafossils of the western United States through 1988" (PDF). In Lucas, S.G.; Hunt, A.P. (eds.). Dawn of the age of dinosaurs in the American Southwest. Albuquerque: New Mexico Museum of Natural History. pp. 189–222.
- 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, Cham: Springer International Publishing, vol. 46, pp. 545–622, doi:10.1007/978-3-319-68009-5_13, ISBN 978-3-319-68008-8, retrieved 2022-11-21
- Parker, William G. (2006). "The stratigraphic distribution of major fossil localities in Petrified Forest National Park, Arizona" (PDF). In Parker, William G.; Ash, Sidney R.; Irmis, Randall B. (eds.). A century of research at Petrified Forest National Park : geology and paleontology. Vol. 62. Museum of Northern Arizona. pp. 46–64. ISBN 0-89734-120-1. OCLC 71015548.
- 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: 354–365.
- Daugherty, Lyman H. (1963). "Triassic Roots from the Petrified Forest National Park". American Journal of Botany. 50 (8): 802–805. doi:10.1002/j.1537-2197.1963.tb10649.x. hdl:2027.42/141301. ISSN 0002-9122.
- Frank H. Knowlton (1889). "New species of fossil wood (Araucarioxylon arizonicum) from Arizona and New Mexico" (PDF). Proceedings of the United States National Museum. 11 (676): 1–5. doi:10.5479/si.00963801.11-676.1.
- Ash, 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): 95–105. JSTOR 40024387.
- Ash, Sidney R. (1974). "Upper Triassic plants of Canon del Cobre, New Mexico". New Mexico Geological Society Guidebook. 25: 179–184.
- Ash, Sidney R. (1989). "The upper Triassic Chinle flora of the Zuni Mountains, New Mexico" (PDF). New Mexico Geological Society. 40: 225–230. doi:10.56577/ffc-40.225. S2CID 251985942.
- "Trees to Stone" (PDF). National Park Service. 2006. Archived (PDF) from the original on September 7, 2015. Retrieved October 3, 2010.
- Axsmith, Brian J.; Ash, Sidney R. (2006). "Two rare fossil cones from the Upper Triassic Chinle Formation in Petrified Forest National Park, Arizona, and New Mexico". Museum of Northern Arizona Bulletin. 62: 82–94.
- Ash, Sidney R. (1991). "A New Pinnate Cycad Leaf from the Upper Triassic Chinle Formation of Arizona". Botanical Gazette. 152 (1): 123–131. doi:10.1086/337871. ISSN 0006-8071. S2CID 83627771.
- Ash, Sidney R. (1967). "The Chinle (Upper Triassic) megaflora of the Zuni Mountains, New Mexico" (PDF). New Mexico Geological Society Fall Field Conference Guidebook. 18: 125–131. doi:10.56577/ffc-18.125. S2CID 11630110.
- Ash, Sidney R. (1973). "Two New Late Triassic Plants from the Petrified Forest of Arizona". Journal of Paleontology. 47 (1): 46–53. JSTOR 1302865.
- Ash, Sidney R. (2006). "Chilbinia Gen. Nov., an Archaic Seed Fern in the Late Triassic Chinle Formation of Arizona, USA". Palaeontology. 49 (2): 237–245. doi:10.1111/j.1475-4983.2006.00542.x. ISSN 0031-0239. S2CID 129438630.
- Ash, Sidney R. (1972). "Late Triassic plants from the Chinle Formation in north-eastern Arizona" (PDF). Palaeontology. 15 (4): 598–618.
- Ash, Sidney (1996). "Evidence of arthropod-plant interactions in the Upper Triassic of the southwestern United States". Lethaia. 29 (3): 237–248. doi:10.1111/j.1502-3931.1996.tb01657.x. ISSN 0024-1164.
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- Ash, Sidney R. (1970). "Dinophyton, a problematical new plant genus from the Upper Triassic of the south-western United States" (PDF). Palaeontology. 13 (4): 646–663.
- Ash, Sidney R. (1977). "An unusual bennettitalean leaf from the Upper Triassic of the south-western United States" (PDF). Palaeontology. 20 (3): 641–659.
- Ash, Sidney R. (1970). "Pagiophyllum simpsonii, a New Conifer from the Chinle Formation (Upper Triassic) of Arizona". Journal of Paleontology. 44 (5): 945–952. JSTOR 1302730.
- Ash, Sidney; Litwin, Ronald J. (1996). "Two new species of the pinnate microsporophyll Pramelreuthia from the upper Triassic of the southwestern United States". American Journal of Botany. 83 (8): 1091–1099. doi:10.1002/j.1537-2197.1996.tb12807.x.
- Ash, Sidney R.; Hasiotis, Stephen T. (2013-04-01). "New occurrences of the controversial Late Triassic plant fossil Sanmiguelia Brown and associated ichnofossils in the Chinle Formation of Arizona and Utah, USA". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 268 (1): 65–82. doi:10.1127/0077-7749/2013/0316. ISSN 0077-7749.
- Ash, 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): 751–754. JSTOR 1304404.
- Ash, Sidney R. (1968). "A new species of Williamsonia from the Upper Triassic Chinle Formation of New Mexico". Journal of the Linnean Society of London, Botany. 61 (384): 113–120. doi:10.1111/j.1095-8339.1968.tb00108.x.
- "Fossil Trees or Petrified Wood" (PDF). University of Arizona. 2012. Retrieved October 14, 2021.
- Herrick, Alisa S.; Fastovsky, David E.; Hoke, Gregory D. (1999). "OCCURRENCES OF ZAMITES POWELLII IN OLDEST NORIAN STRATA IN PETRIFIED FOREST NATIONAL PARK, ARIZONA" (PDF). National Park Service Paleontological Research. 4: 91–95.
- Milner, 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: 410–413.
- Ash, S.R. (1969). "Ferns from the Chinle Formation (Upper Triassic) in the Fort Wingate area, New Mexico" (PDF). United States Geological Survey, Professional Paper. Professional Paper. 613-D: 1–40. doi:10.3133/pp613d. ISSN 2330-7102.
- Daugherty, Lyman H. (1960). "Itopsidema, A New Genus of the Osmundaceae from the Triassic of Arizona". American Journal of Botany. 47 (9): 771–777. doi:10.1002/j.1537-2197.1960.tb07164.x.
- Ash, Sidney (2000). "Evidence of oribatid mite herbivory in the stem of a Late Triassic tree fern from Arizona". Journal of Paleontology. 74 (6): 1065–1071. doi:10.1666/0022-3360(2000)074<1065:EOOMHI>2.0.CO;2. ISSN 0022-3360. S2CID 86324641.
- Ash, Sidney; Litwin, Ronald J.; Traverse, Alfred (1982). "The Upper Triassic fern Phlebopteris smithii (Daugherty) Arnold and its spores". Palynology. 6 (1): 203–219. doi:10.1080/01916122.1982.9989242. ISSN 0191-6122.
- Ash, Sidney (1999). "An Upper Triassic Sphenopteris Showing Evidence of Insect Predation from Petrified Forest National Park, Arizona". International Journal of Plant Sciences. 160 (1): 208–215. doi:10.1086/314115. ISSN 1058-5893. S2CID 85020560.
- Miller, Charles N. (1968). "The Lepidophytic Affinities of the Genus Chinlea and Osmundites Walkeri". American Journal of Botany. 55 (1): 109–115. doi:10.1002/j.1537-2197.1968.tb06950.x.
- Rothwell, Gar W.; R. Ash, Sidney (2015). "Internal anatomy of the Late Triassic Equisetocaulis gen. nov., and the evolution of modern horsetails". The Journal of the Torrey Botanical Society. 142 (1): 27–37. doi:10.3159/TORREY-D-14-00042.1. ISSN 1095-5674. S2CID 86841184.
- Holt, Edward L. (1947). "Upright Trunks of Neocalamites from the Upper Triassic of Western Colorado". The Journal of Geology. 55 (6): 511–513. doi:10.1086/625462. ISSN 0022-1376. S2CID 129374986.
- Miller, Gary L.; Ash, Sidney R. (1988). "The oldest freshwater decapod crustacean, from the Triassic of Arizona" (PDF). Palaeontology. 31 (2): 273–279.
- Sidney R. Ash & Geoffrey T. Creber (2000). "The Late Araucarioxylon arizonicum Trees of the Petrified Forest National Park, Arizona, USA". Palaeontology. 43: 22–23. doi:10.1111/1475-4983.00116. S2CID 128691956.
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