Archer City Formation
Archer City Formation | |
---|---|
Type | Formation |
Unit of | Bowie Group |
Underlies | Nocona Formation |
Overlies | Markley Formation |
Lithology | |
Primary | mudstone |
Other | sandstone, siltstone |
Location | |
Region | Texas |
Country | United States |
Type section | |
Named for | Archer City, Texas |
Named by | Hentz & Brown, 1987 |
The Archer City Formation is a
The sediments of the Archer City Formation reconstruct a coastal
The Archer City Formation preserves a diverse fauna of fossil
History and stratigraphy
Fossil bonebeds in the vicinity of Archer City were first investigated in detail by Alfred Romer and Llewellyn Price, starting in the late 1920s.[3][4][5][6] At the time, these bonebeds were assigned to the Pueblo, Moran, or Putnam formations of the Cisco Group. The Archer City Formation was first named in a 1987 geologic map seeking to update the stratigraphy of North Texas.[7] The formation and its stratigraphic placement were formalized in text a year later.[8]
The formation outcrops in an arc from Montague County in the east, through Clay, Archer, and Young counties, as far as Throckmorton County in the west. It is most broadly exposed in Clay and Archer counties, including under its namesake of Archer City.[7][8][9]
The Archer City Formation is a unit of the Bowie Group, lying above the Markley Formation and below the Nocona Formation of the Wichita Group.[7][8][1] Some publications have labelled the Nocona Formation as the "Upper Archer City Formation", thus considering the Archer City Formation to be a unit of the Wichita Group.[10] This proposal is not widely agreed upon.[11][9] The Cisco Group and its constituent formations have been restricted to marine strata further south and west. Of these strata, the Archer City Formation is roughly equivalent in time to the uppermost Pueblo Formation, the Moran Formation, the Sedwick Formation, and the Santa Anna Branch shale (= Putnam Formation), from oldest to youngest.[7][8][2]
Age
Based on correlations with coastal strata further west, the Carboniferous-Permian boundary is positioned near the top of the Markley Formation. This suggests that the Archer City Formation occupies most of the Asselian (299–293 Ma), the first global stage of the Permian Period.
Paleoenvironment
As with the rest of the Texas red beds, the Archer City Formation was deposited on a coastal plain between an inland marine basin in the west and patches of steadily eroding mountains in the north and east. Some of the mountains are still standing in the present day, such as the Wichita Mountains and Arbuckle Mountains, while others have been fully eroded or buried, such as the Texan portion of the Ouachita Mountains. The marine basin is formally known as the Midland Basin, a major component of the Permian Basin oil field.[8][2] Rising sea levels through the Early Permian allowed the coastline to gradually transgress northward and eastward. The major bonebed sites of the Archer City Formation were probably 40–60 km (25–37 miles) away from the coast.[2]
During the Permian, the area was near the
Geology
In terms of their
Sandstone beds
By volume, the most prevalent sandstone beds are
Some sandstone beds are isolated straight channel fills, without corresponding riverbank deposits.
Paleosols
Four different types of paleosol (labelled types E through H) have been identified in the Archer City Formation.[2][13] Three (F, G, and H) first appear in this formation, while type E paleosols are retained from the underlying Markley Formation. All four continue to persist through the Texas Lower Permian up until an aridification event in the mid-Clear Fork Group. The paleosols are generally dark red or brown, with only intermittent gleying in the type E variety. The Archer City Formation mostly lacks the high-humidity paleosol varieties of the Markley Formation (types A through D).[2][13]
Type E paleosols are silty or fine sandy soils with persistent mottling, hematite nodules, and few distinct horizons. They are a type of entisol, young soils corresponding to isolated, frequently disturbed areas with a high water table, such as riverbanks.[2][13] Type F paleosols are alfisols, patterned with deep root casts and numerous horizons, including intermediate layers with calcareous nodules and smectite clay. They develop in stable forested uplands with a low water table and a semi-arid to subhumid climate (~70 cm of annual precipitation).[2][13] Type G paleosols are similar, with sandy vertical cracks and abundant calcareous nodules. They qualify as vertisols, inundated and dried at a seasonal frequency along the margins of a floodplain.[2][13] Type H paleosols have an even greater proportion of calcareous minerals, forming blocky crusts interspersed among chlorite- and mica-rich clay. They could be termed aridisols or (more broadly) inceptisols, deposited in dry upland areas free from the influence of groundwater.[2][13]
Paleobiota
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Synapsids
Synapsids of the Archer City Formation
| |||
---|---|---|---|
Species | Material | Notes | Images |
Apsisaurus witteri[14] | A partial skeleton | A varanopid,[15] originally identified as a diapsid reptile.[14] | |
Dimetrodon milleri[16] | Nearly complete skeleton[16][5][1][17] | A small sail-backed sphenacodontid | |
Edaphosaurus boanerges[5] | Isolated neural spines and at least one partial skeleton[1][17] | A common medium-sized edaphosaurid, often confused with Edaphosaurus cruciger.[5] | |
Lupeosaurus kayi[16] | Limb and hip bones and vertebrae[16][5][17] | A small basal edaphosaurid[18] | |
Ophiacodon retroversus | Rare fragments[5] | A large ophiacodontid, also described under the names Theropleura and Diopeus. | |
Ophiacodon uniformis | A partial skeleton with a well-preserved skull[1][5] | A medium-sized ophiacodontid, also described under the name Poliosaurus.[5] | |
Stereophallodon ciscoensis[16] | Skull fragments and vertebrae[5][17][10] | A large ophiacodontid |
Reptiles
Reptiles of the Archer City Formation | |||
---|---|---|---|
Species | Material | Notes | Images |
Bolosaurus striatus | A jaw[1][17] | A bolosaurid parareptile | |
Protorothyris archeri[19] | Five skulls with associated postcranial material[20][17] | A protorothyridid eureptile | |
Romeria prima[20] | A skull[20] | A captorhinid eureptile | |
Romeria texana[19] | A partial skull and partial skeleton[1][20] | A captorhinid eureptile |
Temnospondyls
Temnospondyls of the Archer City Formation | |||
---|---|---|---|
Species | Material | Notes | Images |
Acheloma cumminsi | Partial skull and postcrania[21][1] | A trematopid | |
Aspidosaurus sp. | Neural spine armor fragments[22][23] | A dissorophid | |
Broiliellus brevis[22] | Two skulls, one with a partial skeleton[22] | A dissorophid | |
Brevidorsum profundum[22] | Partial skull and postcrania[22][17][23] | A dissorophid | |
Diploseira angusta[24] | A partial skeleton[22] | A dissorophid, formerly considered a species of Dissorophus.[22] | |
Edops craigi | Several skulls and postcrania[25][17][10] | An edopoid | |
Eryops megacephalus | Jaws and other fragments[1][17][10][26] | A common eryopid | |
Neldasaurus wrightae[27] | Four partial skulls and postcania[27][17][10][28] | A trimerorhachid dvinosaur | |
"Parioxys" bolli[29] | A partial skeleton[29][17] | A temnospondyl of uncertain affinities. Parioxys ferricolus, the more complete type species of Parioxys, has variably been interpreted as an eryopoid or a dissorophid."Parioxys" bolli is based on more fragmentary fossils and may belong to an unrelated genus, perhaps a trematopid related to Ecolsonia cutlerensis.[30] | |
Pasawioops cf. mayi | A skull[31] | A micropholid amphibamiform | |
Phonerpeton pricei[32] | At least seven skulls with associated postcranial fragments[32] | A trematopid, formerly considered a species of Acheloma.[21] | |
Reiszerpeton renascentis | A skull[31] | A dissorophid | |
Tersomius texensis | A skull[17][31] | A micropholid amphibamiform | |
Trimerorhachis sp. | A trimerorhachid dvinosaur. Reports from the Archer City Formation[17][10] are unsubstantiated, though it is known from time-equivalent strata in New Mexico.[33] | ||
Zatrachys serratus | Skull fragments[1][17][10] | A zatracheid |
Other amphibians
Non-temnospondyl amphibians of the Archer City Formation | |||
---|---|---|---|
Species | Material | Notes | Images |
Archeria crassidisca | Jaws and vertebrae[34][17][1] | An | |
Diadectes sideropelicus | Jaws and vertebrae[3][4][17][1] | A diadectomorph | |
Diplocaulus sp. | Vertebrae[4][17] | A diplocaulid nectridean | |
Pantylus cordatus | Multiple skeletons in varying states of completeness[35][17][1] | A pantylid microsaur | |
Sauropleura bairdi | Partial skeleton[36] | A urocordylid nectridean | |
Seymouria baylorensis | Vertebrae[1] | A seymouriamorph |
Fish
Scales of indeterminate
Fish of the Archer City Formation | |||
---|---|---|---|
Species | Material | Notes | Images |
Ectosteorhachis nitidus | Scales, jaws, and a skull[40][1][39] | A megalichthyid tetrapodomorph | |
Orthacanthus compressus | Teeth[39] | A xenacanth "shark" | |
Orthacanthus texensis | Teeth, fin spines, cartilage fragments, and a skull[1][39] | A xenacanth "shark" | |
Sagenodus sp. | Tooth plates[1] | A lungfish |
Plants
Plant fossils in the Archer City Formation are concentrated at two sites in Clay County: Kola Switch and Sanzenbacher Ranch.[9][41] Both sites were discovered in 1940–1941 by Adolph H. Witte, a local geologist working for the WPA. Though Witte's original collections have been lost, he sampled the sites further in 1961, along with USGS geologists Sergius H. Mamay and Arthur D. Watt. On behalf of the USNM, Mamay led another expedition in 1990–1991.[9][41]
The floral diversity of the Archer City Formation strongly overlaps with other Asselian-Sakmarian formations in the southwestern United States. These include the
Kola Switch
The Kola Switch site is divided into three different layers in a 1.4 meter (4.6 feet) thick interval, each with a different set of fossils. The lower bed is pale upwards-fining siltstone, the middle bed is dark shale with carbonaceous impressions, and the upper bed is greenish claystone.[9]
The
Conversely, the middle bed is almost entirely marattialean ferns. These include Pecopteris cf. jongmansii, Aphlebia erdmannii, Asterotheca sp, and several more unnamed species. Sphenophytes such as Sphenophyllum are also present.[9] Vesicaspora and Potonieisporites continue to make up a significant portion of the palynomorphs, though Knoxisporites cf. ruhlandii (indeterminate spores), Cyclogranisporites spp. (marattialean spores), and Punctatisporites spp. (marattialean spores) are even more dominant. The middle bed represents foliage washed into a nearby stagnant pond.[9]
The upper bed has the greatest portion of sphenophytes, not just sphenophylls (Sphenophyllum cf. thonii) but also
Sanzenbacher Ranch
The Sanzenbacher flora occupies a narrow layer of greyish claystone coarsening upwards to buff-colored siltstone.[41] The most abundant plants are dry-soil species of seed ferns and conifers. Seed fern species include Autunia conferta, Sphenopteris germanica, Neurodontopteris auriculata, Odontopteris subcrenulata, and Rhachiphyllum schenkii, among others. Walchia is the most common conifer, followed by Cordaites.[41] Riparian plants are less common but far from rare, giving Sanzenbacher a 'mixed' ecosystem character similar to, but drier than, the upper bed of Kola Switch.[9] Marattialean ferns such as Pecopteris and Asterotheca are occasionally prevalent. Sphenophytes include Calamites, Annularia spicata, and to a lesser extent species of Sphenophyllum. The most common palynomorphs are seed fern pollen (Vesicaspora, Wilsonites, Anguisporites), while conifer pollen (Potonieisporites) and spores are rarer.[41] Still, the palynomorph diversity of Sanzenbacher is much greater than at Kola Switch.[9]
See also
- Red Beds of Texas and Oklahoma
- List of fossiliferous stratigraphic units in Texas
- Paleontology in Texas
- Permian
References
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- ^ a b Romer, A.S. (1928). "Vertebrate faunal horizons in the Texas Permo-Carboniferous red beds" (PDF). University of Texas Bulletin. 2801: 67–108.
- ^ ISSN 0016-7606.
- ^ doi:10.1130/spe28-p1
- ^ Romer, Alfred Sherwood (27 November 1974). "The stratigraphy of the Permian Wichita redbeds of Texas". Breviora. 427: 1–31.
- ^ a b c d Hentz, Tucker F.; Brown, L.F. Jr (1987), "Wichita Falls-Lawton sheet", Geologic atlas of Texas, Austin: The University of Texas and Bureau of Economic Geology
- ^ a b c d e Hentz, Tucker F. (1988). "Lithostratigraphy and Paleoenvironments of Upper Paleozoic Continental Red Beds, North-central Texas: Bowie (new) and Wichita (revised) Groups". The University of Texas at Austin, Bureau of Economic Geology, Report of Investigations. 170.
- ^ PMID 34262228.
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- ^ Wardlaw, Bruce R. (2005). "Age assignment of the Pennsylvanian-Early Permian succession of North Central Texas" (PDF). Permophiles. 46: 21–22.
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- ^ a b c d e Romer, A.S. (1937). "New genera and species of pelycosaurian reptiles" (PDF). Proceedings of the New England Zoological Club. 16: 89–97.
- ^ a b c d e f g h i j k l m n o p q r Hook, Robert W. (1989). "Stratigraphic distribution of tetrapods in the Bowie and Wichita Groups, Permo-Carboniferous of north-central Texas". Permo-Carboniferous Vertebrate Paleontology, Lithostratigraphy, and Depositional Environments of North-Central Texas. Field Trip Guidebook No. 2, 49th Annual Meeting of the Society of Vertebrate Paleontology. Austin. pp. 47–53.
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- ^ a b Llewellyn Ivor Price (1937). "Two new cotylosaurs from the Permian of Texas". Proceedings of the New England Zoölogical Club. 11: 97–102.
- ^ a b c d J. Clark; R. L. Carroll (1973). "Romeriid Reptiles from the Lower Permian". Bulletin of the Museum of Comparative Zoology. 144 (5): 353–407.
- ^ JSTOR 30080836.
- ^ a b c d e f g Carroll, Robert L. (1964). "Early evolution of the dissorophid amphibians". Bulletin of the Museum of Comparative Zoology. 131 (7): 161–250.
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- ^ a b Chase, J.N. (1965). "Neldasaurus wrightae, a new rhachitomous labyrinthodont from the Texas Lower Permian". Bulletin of the Museum of Comparative Zoology. 133 (3): 153–225.
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- ^ a b Carroll, Robert L. (21 February 1964). "The relationships of the rhachitomous amphibian Parioxys". American Museum Novitates (2167).
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- ^ Thomson, Keith Stewart (1964). "Revised generic diagnoses of the fossil fishes Megalichthys and Ectosteorhachis (family Osteolepidae)". Bulletin of the Museum of Comparative Zoology at Harvard University. 131 (9): 283–311.
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- Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Retrieved 17 December 2021.