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.
Non-crurotarsan Archosauromorphs of the Chinle Formation | ||||||
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Genus | Species | State | Member | Abundance | Notes | Images |
C. harrisae [1] |
| 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. | ||||
Doswellia [2] | cf. D. kaltenbachi |
|
| Osteoderms, vertebrae, rib and hip fragments. | A doswelliid archosauriform. | |
Puercosuchus [3] | P. traverorum |
|
| Two monodominant bonebeds. | A carnivorous azendohsaurid archosauromorph. | |
Rugarhynchos [4] | R. sixmilensis |
|
| 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 |
|
| Vertebrae | Moderately-sized tanystropheid vertebrae from the Hayden Quarry, likely representing a new taxon closely related to Langobardisaurus and Tanytrachelos . [7] | |
|
| A small tanystropheid represented by several hundred fossil specimens. | ||||
T. murryi [9] |
|
| 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] |
|
| ||||
T. dornorum [12] |
|
| ||||
T. jacobsi [13] |
| |||||
T. phasmalophos [14] |
|
| ||||
V. campi [15] |
|
| A strange aquatic carnivorous archosauriform, represented by both articulated skeletons and scattered elements like osteoderms and vertebrae. [15] | |||
Miscellaneous amniotes of the Chinle Formation | ||||||
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Genus | Species | State | Member | Abundance | Notes | Images |
A. rectori [17] |
| 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 |
|
| Manual unguals (hand claws). | A drepanosaur related to Drepanosaurus. | |
Avicranium [19] | A. renestoi |
|
| 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] |
|
| 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 |
|
| Articulated vertebral and limb material. | A drepanosaur. | |
Drepanosaurus [21] | D. unguicaudatus |
|
| A drepanosaur. | ||
K. venetus |
|
| Partial dentaries. | A non-mammalian eucynodont. | ||
K. colberti [23] |
| 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] | |||
Microzemiotes [24] | M. sonselaensis |
|
| Partial left dentary with three teeth | A diapsid reptile of uncertain affinities. | |
Palacrodon [25] | Indeterminate |
|
| 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. [26] | |
P. hesternus [27] |
| Known from several hundred remains, but very rare outside of the highly concentrated Placerias Quarry. [27] | A placeriine stahleckeriid dicynodont. | |||
Skybalonyx [28] | S. skapter |
|
| Manual unguals (hand claws). | A drepanosaur which likely had a burrowing lifestyle. | |
U. schneideri [30] |
|
| 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." [31] | A reptile of unknown affinities, probably a carnivorous archosauromorph with venomous capabilities. | ||
Whitakersaurus [32] | W. bermani |
|
| A rhynchocephalian found at Ghost Ranch. | ||
Indeterminate procolophonid [33] | Indeterminate |
| ||||
Color key
| 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 [34] |
|
| Common in the Owl Rock and Petrified forest members. [34] Blue Mesa remains are fragmentary. [34] | A metoposaurid temnospondyl which is a junior synonym of Anaschisma | ||
| A. browni is "possibly the most common tetrapod fossil in the lower Chinle", although its presence in the upper Chinle is "unclear". [37] | 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. [35] [36] | ||||
C. jenkinsi |
| A temnospondyl in the group Stereospondyli, related to Rileymillerus from the Dockum Group of Texas. Possibly a stem-caecilian according to one analysis, [38] though others have disputed this finding | ||||
Funcusvermis [39] | F. gilmorei |
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| Numerous jaw fragments, as well as a referred maxillopalatine, vertebra, and femur | A stem-caecilian | |
Indeterminate |
|
| A stem-group frog. Might be more closely related to crown-group frogs (anurans) than to Early Triassic taxa Triadobatrachus and Czatkobatrachus . | |||
Chondrichthyans of the Chinle Formation | ||||||
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Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
Indeterminate [41] |
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| Only a single tooth is known. [41] | A hybodontiform shark. | ||
L. humblei [43] |
| A hybodontiform shark. Lonchidion remains are common throughout the Carnian microvertebrate sites of the American southwest. [43] | ||||
Palaeoxyris | P. humblei [44] |
|
| Several specimens | An egg capsule of a freshwater hybodont shark. | |
Indeterminate [45] |
|
| Only a single specimen has been recovered from the formation. [45] | |||
R. synergus [46] |
| The crown of its tooth bears a "reticulating ornamentation on [its] occlusal surface[.]" [46] Reticulodus remains are common throughout the Norian microvertebrate sites of the American southwest. [46] | ||||
M. moorei [47] |
| Common in the lower Chinle Formation's microvertebrate localities. [47] | A xenacanthiform shark. | |||
Actinistians (coelacanths) of the Chinle Formation | ||||||
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Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
Indeterminate [50] |
| An actinisitan (coelacanth). | ||||
Color key
| 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 [51] | ||||||
Indeterminate [51] |
| Arganodus toothplates are the most common fossil in the formation from a non-tetrapod. [51] They are evenly distributed across strata, although some individual localities have very high concentrations. [51] | Most Chinlean Arganodus fossils are isolated tooth plates. [51] | |||
C. dorotheae [51] | Named by Case in 1921, in the 1980s it was referred to Arganodus. [51] | |||||
Actinopterygians (ray-finned fish) of the Chinle Formation | ||||||
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Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
Indeterminate [53] |
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| Known only from two vertebrae. [53] | |||
C. dunklei |
| A member of Redfieldiiformes. | ||||
H. weiri |
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| A member of Dapediiformes. [55] | |||
L. hillsi [54] |
| A member of Redfieldiiformes. | ||||
Indeterminate [57] |
| Represented by isolated scales. [57] | ||||
L. sanjuanensis [58] |
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| A member of Semionotiformes. | |||
L. chinleana [59] |
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| A member of Semionotiformes. | |||
Indeterminate |
|
| A member of Saurichthyiformes. | |||
S. stewarti |
| A member of Redfieldiiformes. | ||||
T. kalliokoskii |
| An enigmatic actinopterygian. [55] | ||||
T. dolorensis [54] |
| A member of Palaeonisciformes. [54] | ||||
Indeterminate [62] |
| Common. [62] | 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. [62] | |||
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. [63] Some Fort Wingate plant fossils belong to the "Lake Ciniza beds", a localized patch of grey mudstone corresponding to an ancient lake. [64]
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). [65] [66]
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. [67] [68]
Gymnosperms of the Chinle Formation | ||||||
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Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
Araucariorhiza [69] | A. joae | Uncommon | Roots of conifers similar to modern Araucariaceae. Possibly from the same plant as Araucarioxylon arizonicum . | |||
A. arizonicum, A. sp. [71] |
| Abundant | Petrified trunks of large conifers possibly related to modern Araucariaceae. [74] State fossil of Arizona. | |||
Araucarites | A. rudicula [75] |
|
| Very rare | Large female conifer cones similar to those of araucariacean conifers. | |
Aricycas [76] | A. paulae |
|
| Moderately common | Pinnate cycad leaves | |
Baiera | B. arizonica | Uncommon | Ginkgophyte leaves | |||
Brachyphyllum | B. sp, B. hegewaldia [78] | Uncommon | Conifer leaves and shoots | |||
Carpolithus | C. chinleana |
| Rare | Seeds of uncertain affinities | ||
Cephalotaxopsis | C. sp. |
| Conifer foliage | |||
Charmorgia | C. dijolli |
|
| Rare | Short cycad stems | |
Chilbinia [79] | C. lichii |
|
| Rare | An archaic seed fern with seeds and leaves more similar to Carboniferous-Permian seed ferns than to Triassic forms. | |
Creberanthus | C. bealeii [75] |
| Very rare | Pollen-bearing cones similar to those of some extinct "pteridosperms" (seed ferns). Associated with Alisporites opii, a common palynomorph. | ||
Dadoxylon | D. chaneyi |
|
| Very rare | Possible cordaitalean conifer wood. | |
Dechellyia [80] | 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. [81] [82] | |||
Dinophyton | D. spinosus [83] | 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 [82] |
|
| Uncommon | Leaf-bearing conifer shoots | |
Eoginkgoites | E. sp., E. davidsonii [84] |
| Common within its small stratigraphic range | A bennettitalean with palm-shaped fronds similar to some ginkgo species. | ||
Ginkgoites | G. sp. |
|
| Rare | A ginkgophyte | |
Lindleycladus | L. arizonicus [82] |
|
| 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). [81] | |||
Masculostrobus | M. clathratus [80] |
|
| Locally common | A pollen-bearing cone associated with lattice-shaped Equisetosporites chinleana pollen. | |
Nilssoniopteris | N. ciniza [64] [73] | Uncommon | Large smooth-edged bennettitalean leaves, some of which were originally identified as Macrotaeniopteris magnifola. | |||
Otozamites | O. macombii |
|
| Uncommon | Bennettitalean leaves | |
Pagiophyllum | P. sp., P. duttonia, [64] P. navajoensis, [64] P. readiana, [64] P. zuniana, [64] P. simpsonii [85] | 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, [86] P. yazzi [86] |
|
| Rare | Gymnosperm microsporophylls (pollen-bearing organs) | |
Pterophyllum | P. sp., P. braunianum |
| Uncommon | Bennettitalean leaves | ||
Samaropsis | S. sp., S. puerca |
| 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). | |||
S. adamanica |
| Rare | Petrified stems of a conifer or gnetalean [74] | |||
Williamsonia | W. nizhonii [89] | Rare | A bennettitalean "flower" (female cone) | |||
W. arizonica |
| Uncommon | Stems and petrified wood of a conifer related to A. arizonicum. [74] [90] | |||
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. [81] Zamites powellii was formerly known as Otozamites powellii. | |||
Ferns of the Chinle Formation | ||||||
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Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
Apachea | A. arizonica |
|
| Rare | Dipteridacean fern leaves, possibly damaged specimens of Clathropteris walkeri. [93] | |
Cladophlebis | C. daughertyi, [93] C. subfalcata, C. yazzia, [78] C. sp. | Very common | Large sterile fern leaves of uncertain affinities | |||
Clathropteris | C. walkeri | Common | Dipteridacean fern leaves | |||
Cynepteris [93] | C. sp., C. lasiophora [93] | 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). [81] | |||
Itopsidema [94] | I. vancleavi |
|
| Uncommon | Stems of large osmundacean tree ferns. Some stems show evidence of being bored by oribatid mites. [95] | |
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. [97] | |||
Todites | T. fragilis | Uncommon | Osmundacean fern leaves | |||
Wingatea [93] | W. plumosa | Rare | Gleicheniacean fern leaves previously named as a species of Coniopteris . |
Other plants of the Chinle Formation | ||||||
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Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
Chinlea | C. sp., C. campii |
| Uncommon | Small lycopod stems similar to shrubby forms such as Pleuromeia . [98] | ||
Equisetites | E. sp., E. bradyi | Common | A horsetail indistinguishable from modern Equisetum . | |||
Equisetocalis [99] | E. muirii |
|
| Concentrated in a narrow stratigraphic range (the Newspaper Rock sandstone bed) | Small three-dimensional horsetail stems preserved in pyrite nodules. | |
Isoetites | I. circularis |
|
| Rare | Quillwort shoots | |
Lycostrobus | L. chinleana |
| 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 |
|
| Uncommon | Stems and leaves of a large sphenophyte (horsetail) more typical of Southern Hemisphere plant assemblages. | |
Selaginella | S. anasazia [80] |
|
| Uncommon | A low-growing lycopsid similar to modern broad-leaved species of Selaginella, such as S. kraussiana |
Arthropods of the Chinle Formation | ||||||
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Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
Enoplocytia | E. porteri [101] |
|
| Single well-preserved fossil | An erymid crayfish | |
P. divergus |
|
| A species of bark beetle, evidenced by trace fossils of tracks made on A. arizonicum specimens. | |||
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Parrishia is an extinct genus of sphenosuchian crocodylomorph known from the Late Triassic Chinle, Dockum, and Santa Rosa Formations in Arizona and New Mexico.
Uatchitodon is an extinct genus of Late Triassic reptile known only from isolated teeth. Based on the structure of the teeth, Uatchitodon was probably a carnivorous archosauromorph. Folded grooves on the teeth indicate that the animal was likely venomous, with the grooves being channels for salivary venom. The teeth are similar to those of living venomous squamates such as Heloderma and venomous snakes. Uatchitodon is the earliest known venomous reptile.
The Bull Canyon Formation is a geological formation of Late Triassic (Norian) age in eastern New Mexico and the Texas Panhandle. It is one of several formations encompassed by the Dockum Group.
The Colorado City Formation is a Late Triassic geologic formation in the Dockum Group of Texas, United States. It has previously been known as the Iatan Member, Colorado City Member or 'Pre-Tecovas Horizon'.
Land vertebrate faunachrons (LVFs) are biochronological units used to correlate and date terrestrial sediments and fossils based on their tetrapod faunas. First formulated on a global scale by Spencer G. Lucas in 1998, LVFs are primarily used within the Triassic Period, though Lucas later designated LVFs for other periods as well. Eight worldwide LVFs are defined for the Triassic. The first two earliest Triassic LVFs, the Lootsbergian and Nonesian, are based on South African synapsids and faunal assemblage zones estimated to correspond to the Early Triassic. These are followed by the Perovkan and Berdyankian, based on temnospondyl amphibians and Russian assemblages estimated to be from the Middle Triassic. The youngest four Triassic LVFs, the Otischalkian, Adamanian, Revueltian, and Apachean, are based on aetosaur and phytosaur reptiles common in the Late Triassic of the southwestern United States.