Paleobiota of the Chinle Formation
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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
Archosauromorphs
Phytosaurs
| Phytosaurs of the Chinle Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | State | Member | Abundance | Notes | Images |
|
L. crosbiensis[1] |
|
A basal leptosuchomorph related to Smilosuchus. |  | |||
|
M. buceros[2] |
|
A mystriosuchin. The type species of Machaeroprosopus. |  | |||
| M. jablonskiae[3] |
|
|
Partial skull | An early-diverging mystriosuchin.[3] | ||
|
M. mccauleyi[2] |
|
A mystriosuchin. |  | |||
|
M. pristinus[2] |
|
A mystriosuchin. The type species of "Pseudopalatus", which is now considered a synonym of Machaeroprosopus. |  | |||
|
cf. Paleorhinus[4] |
Indeterminate[4] |
|
|
 | ||
| Pravusuchus[5] | P. hortus |
|
|
Three skulls. | A basal leptosuchomorph closely related to Mystriosuchini[5][6] or Nicrosaurus.[7] | |
| Protome[8] | P. batalaria |
|
|
Partial skull and jaw. | A phytosaur originally described as a juvenile Leptosuchus, but probably an unrelated non-leptosuchomorph[8] or mystriosuchin.[7] |  |
|
R. gregorii[9] |
A large late-surviving mystriosuchin. Either a close relative of Machaeroprosopus (formerly known as Pseudopalatus),[11] or a subgenus of that taxon.[10][6][7] | _gregorii_skeletal.png) | ||||
|
S. adamanensis[1] |
|
Known from a single skull |
Previously referred to Leptosuchus, actually referable to Smilosuchus.[5] |
 | ||
|
S. gregorii |
|
|
Known from a handful of skulls. |
A basal leptosuchomorph, split off from Leptosuchus. |
 | |
|
S. lithodendrorum[5] |
|
|
Known from only one skull. |
Previously considered synonymous with S. adamanensis. |
||
Suchians
Color key
|
Notes Uncertain or tentative taxa are in small text; |
| Suchians of the Chinle Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | State | Member | Abundance | Notes | Images |
| Acaenasuchus[12] | A. geoffreyi[12] |
|
Known from a handful of isolated osteoderms.[12] | A controversial suchian based primarily on osteoderms. Some paleontologists have considered Acaenasuchus to be juvenile Desmatosuchus haplocerus scutes, while others considered it a separate genus of small aetosaurs.[12] In 2020 it was redescribed as an aetosauriform related to, but not within, Aetosauria. It is also related to Revueltosaurus (also from the Chinle) and the armored reptile Euscolosuchus from Virginia.[13] |  | |
| Adamanasuchus | A. eisenhardtae |
|
|
Osteoderms and skull and postcranial fragments. | A basal desmatosuchine aetosaur related to Calyptosuchus and Scutarx.[14] | |
|
C. wellesi[16] |
|
|
Common, although "non-armor material is comparatively rare".[16] |
A basal desmatosuchine aetosaur originally considered a species of Stagonolepis. | ||
|
D. spurensis[18] |
|
|
Numerous osteoderms and other skeletal material | A large desmatosuchin aetosaur which was fairly common in the lower part of the Chinle Formation. Prior to 2008, fossils of D. spurensis were listed as the species D. haplocerus, until it was determined that D. haplocerus was a species name originally based on undiagnostic fossils.[14] |  | |
|
D. smalli[19] |
|
|
A single lateral osteoderm. | A desmatosuchin aetosaur which is very rare in the Chinle Formation. One of the youngest known occurrences of the genus Desmatosuchus.[14] | ||
|
E. okeeffeae |
|
|
A six-foot-long shuvosaurid from the Coelophysis quarry of Ghost Ranch. |  | ||
|
E. lacrimosa |
|
|
Partial skull, a cervical vertebra, pubes, left hindlimb and three osteoderms | An early crocodylomorph from the Coelophysis quarry of Ghost Ranch. It had a short and reinforced facial region, likely adapted for powerful bites. |  | |
|
H. agilis[21] |
|
An early-diverging crocodylomorph |  | |||
| Kryphioparma[22] | K. caerula |
|
|
Osteoderms. | An aetosaur described in 2023, probably related to other typothoracines.[22] | |
| Labrujasuchus[23] | L. expectatus |
|
|
Partial skeleton and other postcrania | A shuvosaurid from the Hayden Quarry of Ghost Ranch.[23] | |
|
P. andressorum[24] |
|
|
Osteoderms |
A significant number of researchers feel that the North American material referred to the German Paratypothorax species P. andressorum by Hunt and Lucas in 1992 is actually distinct.[24] |
||
|
Indeterminate[25] |
|
Osteoderms and minor postcranial fragments. | A paratypothoracin typothoracine aetosaur known from isolated material similar to more complete specimens from Germany.[26] | |||
|
P. mccreai[27] |
|
A dubious genus of crocodylomorph, known from isolated vertebrae | ||||
|
P. gracilis[28] |
|
A poposaurid pseudosuchian. |  | |||
|
P. kirkpatricki[29] |
|
A rauisuchid. "Rauisuchian" fossils from the Chinle are commonly referred to Postosuchus, under the assumption that it was the only large rauisuchian in the formation. The recognition of Vivaron indicates that this is not the case. Less ambiguous Postosuchus fossils are known from Texas. |  | |||
|
R. callenderi[31] |
|
|
A suchian with extensive armor and adaptations for herbivory, including teeth initially mistaken as belonging to ornithischian dinosaurs. It was probably an aetosauriform (aetosaur relative). |  | ||
|
R. hunti[32] |
|
|
||||
|
R. chamaensis |
|
Osteoderms and possible ankle and vertebrae remains. |
A late-surviving paratypothoracin typothoracine aetosaur. Originally referred to Desmatosuchus, but later reinterpreted as a relative of Paratypothorax based on a phylogenetic analysis performed on the remains by Parker in 2003.[33] New genus names were erected independently by Parker (coining the name Heliocanthus) and Lucas et al. (coining the name Rioarribasuchus), prompting an investigation into reports of unethical taxonomic claim-jumping by the latter party. |
|||
|
Indeterminate[34] |
|
|
Jaw fragment. |
Identified from a fossil which has been reinterpreted as an indeterminate "rauisuchian". |
||
| Scutarx[14] | S. deltatylus[14] |
|
|
Four partial skeletons including skull fragments. | A large basal desmatosuchine aetosaur based on fossils originally referred to "Stagonolepis" (=Calyptosuchus) wellesi, a close relative. Fossils of Scutarx represent the highest stratigraphic occurrence of Stagonolepis-like aetosaurs in Petrified Forest National Park. |  |
|
S. inexpectatus[35] |
|
Following a rediagnosis of the genus and species, only shuvosaurid fossils from the Cooper Canyon Formation are reliably identifiable as Shuvosaurus itself.[36] |
||||
|
S. cedrus[37] |
|
|
More than 950 disassociated and non-articulated bones belonging to at least 36 individuals[37] |
A shuvosaurid that may have shifted from quadrupedal to bipedal locomotion through ontogeny.[37] |
||
| Stenomyti | S. huangae |
|
|
Partial skeleton including a well-preserved skull. | A small aetosaurine aetosaur similar to Aetosaurus. | |
|
T. coccinarum[38] |
|
Common in the Owl Rock and Petrified Forest Members.[38] |
A large, wide-bodied typothoracine aetosaur abundant throughout the Chinle Formation. Almost all of the known Chinle Typothorax fossils are isolated whole or fragmentary osteoderms.[38] |
 | ||
| Tecovasuchus[22] | T. chatterjeei |
|
|
Osteoderms. | A paratypothoracin aetosaur, previously thought to be more widespread in the formation.[22] | |
|
V. haydeni[39] |
|
|
Skull fragments and hip bones | A large rauisuchid from the Hayden Quarry of Ghost Ranch, similar to Postosuchus. |  | |
Ornithodirans
"Prosauropod" tracks are present in the Redonda, Sloan Canyon, and Sheep Pen Sandstone formations, though these geological units are typically regarded as part of the Dockum Group rather than the Chinle Formation. Prosauropod tracks might be present in the Rock Point Formation as well. Geographically, the tracks are present in New Mexico.[40]
Theropod tracks have been found in Utah and New Mexico recovered from the Redonda, Sloan Canyon, and Sheep Pen Sandstone formations.[40] Indeterminate theropod remains are present throughout unambiguous strata of the Chinle Formation, including the Petrified Forest, Bluewater Creek, and Rock Point members of New Mexico.[40]
Color key
|
Notes Uncertain or tentative taxa are in small text; |
| Ornithodirans of the Chinle Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | State | Member | Abundance | Notes | Images |
|
C. arizonensis[40] |
|
|
A coelophysine coelophysid from the Placerias Quarry. |  | ||
|
C. bryansmalli[40] |
|
|
A large saurischian with similarities to herrerasaurids and Tawa hallae. |  | ||
|
C. bauri |
|
|
A coelophysid. Though originally based on rare fragments, in the 1940s numerous skeletons of C. bauri were discovered in a bonebed at Ghost Ranch in New Mexico |  | ||
| C. sp.[42] |
|
|
Originally assigned to C. bauri, but likely a different taxon.[42] |
|||
|
C. longicollis[40] |
|
|
Now considered a junior synonym of C. bauri. |
 | ||
|
C. willistoni |
|
|
Now considered a junior synonym of C. bauri. |
 | ||
| Dromomeron | D. romeri |
|
|
A lagerpetid pterosauromorph found at various Ghost Ranch quarries and elsewhere in the Chinle Formation. |  | |
|
D. chauliodus |
|
|
Skull and neck vertebrae fragments | A saurischian from the Coelophysis Quarry. with a short skull and enlarged teeth. |  | |
|
E. mcintireae |
|
|
Partial mandible, teeth, and wing finger bone |
An early-diverging pterosaur |
.png) | |
|
E. baldwini |
|
|
A silesaurid dinosauriform closely related to the Polish genus Silesaurus.[44] |
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K. williamparkeri |
|
|
A silesaurid dinosauriform with adaptations for herbivory. |
 | ||
|
P. bucculentus |
|
|
A single partial skull |
A short-skulled saurischian from the Coelophysis Quarry. Likely related to Chindesaurus, Daemonosaurus, and Tawa. |
 | |
|
T. hallae |
|
|
A saurischian showing a mosaic of features similar to neotheropods and herrerasaurids. |  | ||
Other archosauromorphs
| Non-crurotarsan archosauromorphs of the Chinle Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | State | Member | Abundance | Notes | Images |
|
A. oligos |
|
Cervical, dorsal, and caudal vertebrae |
A tanystropheid archosauromorph bearing elongated spikes on the vertebral neural spines[47] |
 | ||
|
C. harrisae[48] |
|
|
Teeth |
An archosauriform represented only by teeth.[48] It is treated as indeterminate archosauriform remains by Irmis in 2005.[48] It was originally thought to be an ornithischian dinosaur. |
 | |
| Doswellia[49] | cf. D. kaltenbachi |
|
|
Osteoderms, vertebrae, rib and hip fragments. | A doswelliid archosauriform. |  |
| Puercosuchus[50] | P. traverorum |
|
|
Two monodominant bonebeds. |
A carnivorous malerisaurine azendohsaurid archosauromorph. |
 |
| Rugarhynchos[51] | R. sixmilensis |
|
|
Skull and postcranial fragments. | A doswelliid archosauriform. Originally described as a species of Doswellia,[52] but subsequently transferred to a separate genus. |  |
| Syntomiprosopus[53] | S. sucherorum |
|
Two to four individuals from a single quarry.[53] |
A short-faced archosauriform from the Placerias / Downs' Quarry. Possibly an unusual early-diverging crocodylomorph. Appears convergent with some Late Cretaceous notosuchians.[53] |
||
| Tanystropheidae[54] | Indeterminate |
|
|
Vertebrae | Moderately-sized tanystropheid vertebrae from the Hayden Quarry, likely representing a new taxon closely related to Langobardisaurus and Tanytrachelos.[54] | |
| cf. Tanystropheus[47] | Indeterminate |
|
|
Cervical vertebrae | Tanystropheid neck vertebrae similar to Tanystropheus, but much smaller and later in time than any other Tanystropheus fossils.[47] | |
|
|
A small tanystropheid represented by several hundred fossil specimens. |
 | |||
|
T. murryi[56] |
|
|
An unknown amniote represented by scattered teeth formerly believed to be from an ornithischian dinosaur.[56] Later discoveries of similar teeth in pseudosuchians meant that these could no longer be regarded as anything more specific than some kind of archosauriform.[56] |
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|
T. buettneri[58] |
|
|
A trilophosaurid. | .jpg) | ||
|
T. dornorum[59] |
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A trilophosaurid. | |||
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T. jacobsi[60] |
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A trilophosaurid. | ||||
|
T. phasmalophos[61] |
|
|
A late-surviving trilophosaurid. | |||
|
V. campi[62] |
|
|
A strange aquatic carnivorous archosauriform, represented by both articulated skeletons and scattered elements like osteoderms and vertebrae.[62] |
 | ||
Other reptiles
| Other reptiles of the Chinle Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | State | Member | Abundance | Notes | Images |
|
A. rectori[64] |
|
Known only from a partial skull.[64] |
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.[64] |
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| Ancistronychus[65] | A. paradoxus |
|
|
Manual unguals (hand claws). | A drepanosaur related to Drepanosaurus. | |
| Avicranium[66] | 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. |  |
|
cf. C. tenertesta |
|
|
Parts of carapaces, cervical osteoderms, a skull roof fragment, left pelvic girdle, a caudal vertebra, a possible squamosal |
A terrestrial testudinate (shelled stem-turtle). |
||
|
C. obscurus[67] |
|
|
Known only from a jaw fragment and some isolated teeth.[67] |
Originally believed to be a fish, Colognathus was a strange amniote with distinctive fluted teeth.[67] |
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| Dolabrosaurus | D. aquatilis |
|
|
Articulated vertebral and limb material. | A drepanosaur. | |
| Drepanosaurus[68] | D. unguicaudatus |
|
|
A drepanosaur. |  | |
| Fabanychus[69] | F. monos |
|
|
A drepanosaur. | ||
| Microzemiotes[70] | M. sonselaensis |
|
|
Partial left dentary with three teeth | A diapsid reptile of uncertain affinities. | |
| Palacrodon[71] | P. parkeri[71] |
|
|
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.[72] | |
| Skybalonyx[73] | S. skapter |
|
|
Manual unguals (hand claws). | A drepanosaur which likely had a burrowing lifestyle. | |
|
U. schneideri[75] |
|
|
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."[76] |
A reptile of unknown affinities, probably a carnivorous archosauromorph with venomous capabilities. | ||
| Whitakersaurus[77] | W. bermani |
|
|
A rhynchocephalian found at Ghost Ranch. | ||
| Leptopleuronine indet. | Indeterminate |
|
|
An incomplete skull (specimen MNA V9953)[78] |
Inteterminate leptopleurine procolophonids. | |
|
|
Two skulls (specimens MCZ 9312 and 9313)[79] |
||||
|
Sphenodontia sp.[43] |
Indeterminate |
|
|
A dentary. |
An indeterminate rhynchocephalian. | |
Synapsids
| Synapsids of the Chinle Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | State | Member | Abundance | Notes | Images |
|
K. venetus |
|
|
Partial dentaries. |
A non-mammalian eucynodont. |
||
|
K. colberti[81] |
|
Known only from two teeth.[81] |
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.[81] |
|||
|
P. hesternus[82] |
|
Known from several hundred remains, but very rare outside of the highly concentrated Placerias Quarry bonebed.[82] |
A placeriine stahleckeriid dicynodont. |  | ||
Amphibians
Color key
|
Notes Uncertain or tentative taxa are in small text; |
| Amphibians of the Chinle Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | State | Member | Abundance | Notes | Images |
|
A. gregorii[83] |
|
|
Common in the Owl Rock and Petrified forest members.[83] Blue Mesa remains are fragmentary.[83] |
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".[86] |
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.[84][85] |
 | |||
|
C. jenkinsi |
|
|
A temnospondyl in the group Stereospondyli, related to Rileymillerus from the Dockum Group of Texas. Originally interpreted as a stem-caecilian,[87] though others have disputed this finding. |
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| Funcusvermis[88] | F. gilmorei |
|
|
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. |
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Cartilaginous fish
| Chondrichthyans of the Chinle Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
|
Indeterminate[90] |
|
|
Only a single tooth is known.[90] |
A hybodontiform shark. |  | |
|
L. humblei[92] |
|
A hybodontiform shark. Lonchidion remains are common throughout the microvertebrate sites of the American southwest.[92] | ||||
| L. minimorsus[93] |
|
|
Teeth | |||
| Palaeoxyris | P. humblei[94] |
|
|
Several specimens | An egg capsule of a freshwater hybodont shark. | |
|
Indeterminate[95] |
|
|
Only a single specimen has been recovered from the formation.[95] |
Triassic records of "Phoebodus" from Europe are reclassified to genus Keuperodus,[96] and if this specimen also can be attributed to Keuperodus, this would be the first record from North America.[97] | ||
|
Reticulodus[98] |
R. synergus[98] |
|
The crown of its tooth bears a "reticulating ornamentation on [its] occlusal surface[.]"[98] Reticulodus remains are common throughout the Norian microvertebrate sites of the American southwest.[98] | |||
|
M. moorei[99] |
|
Common in the lower Chinle Formation's microvertebrate localities.[99] |
A xenacanthiform shark. | |||
Lobe-finned fish
Coelacanths
| Actinistians (coelacanths) of the Chinle Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
| Chinlea[101] | C. sorenseni[102] |
|
|
AMNH 5657; AMNH 5652, 5656, 5660, 5704; AMNH 5653 | A freshwater actinisitan (coelacanth). |  |
|
Indeterminate[104] |
|
MNA V346, scale; MNA V7045-7048, isolated quadrates | ||||
Lungfish
Color key
|
Notes Uncertain or tentative taxa are in small text; |
| Dipnoans (lungfish) of the Chinle Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | State | Stratigraphic position | Abundance | Notes | |
|
A. dorotheae[105] |
||||||
|
Indeterminate[105] |
|
Arganodus toothplates are the most common fossil in the formation from a non-tetrapod.[105] They are evenly distributed across strata, although some individual localities have very high concentrations.[105] |
Most Chinlean Arganodus fossils are isolated tooth plates.[105] | |||
|
C. dorotheae[105] |
Named by Case in 1921, in the 1980s it was referred to Arganodus.[105] | |||||
Ray-finned fish
| Actinopterygians (ray-finned fish) of the Chinle Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
|
Indeterminate[107] |
|
|
Known only from two vertebrae.[107] |
 .jpg) | ||
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C. dunklei |
|
A member of Redfieldiiformes. | ||||
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H. weiri |
|
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A member of Dapediiformes.[108] | |||
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L. hillsi[102] |
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A member of Redfieldiiformes. | ||||
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Indeterminate[110] |
|
Represented by isolated scales.[110] | ||||
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Lophionotus[111] |
L. sanjuanensis[111] |
|
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A member of Semionotiformes. | ||
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L. chinleana[112] |
|
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A member of Semionotiformes. | |||
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Indeterminate |
|
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A member of Saurichthyiformes. | |||
|
Synorichthys[102] |
S. stewarti |
|
A member of Redfieldiiformes. | |||
|
T. kalliokoskii |
|
An enigmatic actinopterygian.[108] | ||||
|
T. dolorensis[102] |
|
A member of Palaeonisciformes.[102] | ||||
|
Indeterminate[115] |
|
Common.[115] |
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.[115] | |||
Arthropods
| Arthropods of the Chinle Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
| Enoplocytia | E. porteri[116] |
|
|
Single well-preserved fossil | An erymid crayfish | |
|
Paleoscolytus[117] |
P. divergus |
|
|
A species of bark beetle, evidenced by trace fossils of tracks made on A. arizonicum specimens. |
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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.[118] Some Fort Wingate plant fossils belong to the "Lake Ciniza beds", a localized patch of grey mudstone corresponding to an ancient lake.[119]
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).[120][121]
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.[122][123]
Gymnosperms
| Gymnosperms of the Chinle Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
| Araucariorhiza[124] | A. joae | Uncommon | Roots of conifers similar to modern Araucariaceae. Possibly from the same plant as Araucarioxylon arizonicum. | |||
|
A. arizonicum, A. sp.[126] |
|
Abundant | Petrified trunks of large conifers possibly related to modern Araucariaceae.[129] State fossil of Arizona. | _-_National_Museum_of_Natural_History,_United_States_-_DSC08540.JPG) | ||
| Araucarites | A. rudicula[130] |
|
|
Very rare | Large female conifer cones similar to those of araucariacean conifers. | |
| Aricycas[131] | A. paulae |
|
|
Moderately common | Pinnate cycad leaves | |
| Baiera | B. arizonica | Uncommon | Ginkgophyte leaves | |||
| Brachyphyllum | B. sp,
B. hegewaldia[133] |
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[134] | 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[130] |
|
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[135] | 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.[136][137] | |||
| Dinophyton | D. spinosus[138] | 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[137] |
|
|
Uncommon | Leaf-bearing conifer shoots | |
| Eoginkgoites | E. sp.,
E. davidsonii[139] |
|
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[137] |
|
|
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).[136] | |||
| Masculostrobus | M. clathratus[135] |
|
|
Locally common | A pollen-bearing cone associated with lattice-shaped Equisetosporites chinleana pollen. | |
| Nilssoniopteris | N. ciniza[119][128] | 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,[119] P. navajoensis,[119] P. readiana,[119] P. zuniana,[119] P. simpsonii[140] |
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,[141] P. yazzi[141] |
|
|
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). | |||
|
Schilderia |
S. adamanica |
|
Rare | Petrified stems of a conifer or gnetalean[129] | ||
| Williamsonia | W. nizhonii[144] | Rare | A bennettitalean "flower" (female cone) | |||
|
Woodworthia |
W. arizonica |
|
Uncommon |
Stems and petrified wood of a conifer related to A. arizonicum.[129][145] |
||
| 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.[136] Zamites powellii was formerly known as Otozamites powellii. | |||
Ferns
| Ferns of the Chinle Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
| Apachea | A. arizonica |
|
|
Rare | Dipteridacean fern leaves, possibly damaged specimens of Clathropteris walkeri.[148] | |
| Cladophlebis | C. daughertyi,[148] C. subfalcata,
C. yazzia,[133] C. sp. |
Very common | Large sterile fern leaves of uncertain affinities | |||
| Clathropteris | C. walkeri | Common | Dipteridacean fern leaves | |||
| Cynepteris[148] | C. sp.,
C. lasiophora[148] |
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).[136] | |||
| Itopsidema[149] | I. vancleavi |
|
|
Uncommon | Stems of large osmundacean tree ferns. Some stems show evidence of being bored by oribatid mites.[150] | |
| 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.[152] | |||
| Todites | T. fragilis | Uncommon | Osmundacean fern leaves | |||
| Wingatea[148] | W. plumosa | Rare | Gleicheniacean fern leaves previously named as a species of Coniopteris. | |||
Other plants
| Other plants of the Chinle Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | State | Stratigraphic position | Abundance | Notes | Images |
| Chinlea | C. sp.,
C. campii |
|
Uncommon | Small lycopod stems similar to shrubby forms such as Pleuromeia.[153] | ||
| Equisetites | E. sp.,
E. bradyi |
Common | A horsetail indistinguishable from modern Equisetum. | |||
| Equisetocalis[154] | 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 Equicalastrobus | ||
| 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[135] |
|
|
Uncommon | A low-growing lycopsid similar to modern broad-leaved species of Selaginella, such as S. kraussiana | |