Pitkin Formation

The Pitkin Formation, or Pitkin Limestone, is a fossiliferous geologic formation in northern Arkansas that dates to the Chesterian Series of the late Mississippian.[4] This formation was first named the "Archimedes Limestone" by David Dale Owen in 1858, but was replaced in 1904.[3] The Pitkin conformably overlies the Fayetteville Shale and unconformably underlies the Pennsylvanian-age Hale Formation. Some workers have considered the top of the Pitkin Formation to be a separate formation called the Imo Formation. However more recently, others have considered it as an informal member of the Pitkin Formation.

Pitkin Formation Stratigraphic range: Upper Visean-Serpukhovian[1]
Type	Formation
Sub-units	Imo Shale
Underlies	Hale Formation
Overlies	Fayetteville Formation
Thickness	up to and over 400 feet[2]
Lithology
Primary	Limestone[1]
Other	Shale
Location
Region	Arkansas
Country	United States
Type section
Named for	Pitkin post office, Washington County, Arkansas[3]
Named by	George Irving Adams and Edward Oscar Ulrich

Paleofauna

Early work aimed at creating a comprehensive list for all fossils found in the Pitkin Formation was done by Easton in 1943.[1] Unless otherwise stated, all species below can be found in his 'Fauna of the Pitkin Formation.'

Formanifera

Archaediscus A. stilus[5] Asteroarchaediscus A. rugosus[5] Earlandia[5] Endothyra[1] E. kleina[6] E. phrissa[5] Endothyranella[6] Eosigmoilina E. explicata[5] E. rugosa[5] Eostaffella[5] Eotuberitina[5] Monotaxinoides[5]

Neoarchaediscus[5] Nodosarchaediscus[5] Paramillerella[6] Planospirodiscus[5] Plectogyra[6] Priscella[5] Pseudoammodiscus P. priscus[5] Pseudoglomospira[5] Tetrataxis[5] T. corona[6] Trepeilopsis[5] Zellerina Z. designata[5] Z. discoidea[5]

Porifera, Sponges

A modern Cliona from the coastal waters of northern France.

• Cliona

Scyphozoa

• Conularia Originally considered to be a gstropod.

Anthozoa, Corals

Amplexus Aulopora A. gracilis Caninostrotion C. variablilis Kinkaidia[7] Lesliella[7] Leonardophyllum[7]

Lonsdaleia L. major L. minor Michellinia[8] M. macerimuris[8] Parvaxon[7] Pleurodictyum P. eugenei P. meekanum Syringopora Triplophyllum

• 
  Aulopora from the Silica Formation of Ohio.
• 
  Pleurodictyum americanum from the Givetian Kashong Shale (Hamilton Group) of Livingston County, New York.
• 
  Syringopora from the Boone Formation of Arkansas.

Blastoidea

Pentremites godoni from the Lower Carboniferous of Illinois.

• Pentremites

P. elongatus[9]

P. godoni[9]

P. laminatus[9]

P. obesus[9]

P. platybasis[1]

Crinoidea, Sea Lilies

Agassizocrinus (see unidentified section) A. patulus [10] Aphelecrinus A. planus[10] Bronaughocrinus B. figuratus[10] Camptocrinus[10] Carinocrinus C. stevensi[10] Castillocrinus Catillocrinus[10] Cosmetocrinus C. eventus[10] Cromyocrinus Culmicrinus[10] Cyathocrinus Delocrinus

Dichocrinus[10] Hydreionocrinus Linocrinus L. floweri[10] Onychocrinus O. pulaskiensis[10] Pachylocrinus Paianocrinus P. aptus[10] P. durus[10] Paracymbiocrinus P. pitkini[10] Pelecocrinus P. stereostoma[10] Pentaramicrinus P. modulus[10] Phacelocrinus[10]

Phanocrinus P. cooksoni[10] P. irregularis[10] Poteriocrinus Pterotocrinus P. tridecibrachiatus[10] Scytalocrinus (see unidentified section) S. braggsi[10] S. dunlapi[10] S. garfieldi[10] Taxocrinus T. whitfieldi[10] Telikosocrinus T. caespes T. residuus Zeusocrinus Z. foveatus

• 
  Cyathocrinus goniodactylus, on display at Galerie de paléontologie et d'anatomie comparée in Paris.
• 
  Fossil of Scytalocrinus from Carboniferous of the United States

Ophiuroidea, Brittle Stars

This group was originally place under Stelleroidia in early studies.[1]

• Aganaster

A. singulatus

• Schoenaster

Echinoidea, Sea Urchins

An upper Carboniferous species of Archaeocidaris.

• Archaeocidaris

Worms

Previous studies have grouped these diverse animals into a single, obsolete taxon: Vermes.[1]

• Spirorbis

Bryozoa, "Moss-animals"

Stereo image

Left frame

Right frame

Parallel view ()

Cross-eye view ()

Fossilized skeleton of Archimedes Bryozoan.

Anisotrypa A. solida [1] Archimedes (called Archimedipora in early studies)[1] A. communis [1][11] A. compactoides [11] A. compactus [11] A. distans [1][11] A. fosteri [11] A. fragilis [11] A. intermedia (A. intermedius) [1][11] A. invaginata (A. invaginatus) [1][11] A. lunatus [11] A. magnus [11] A. meekanus [11] A. moorei [11] A. pitkinensis [11]

A. proutana (A. proutanus) [1][11] A. sublaxus [11] A. swallovana (A. swallovanus) [1][11] A. terebriformis [11] Batostomella [1] Chellotrypa C. distans [11] Chilotrypa C. regularis [1] Dichotrypa D. levis [1][11] Dyscritella [1] Fenestella [1] F. cumingsi [11] F. matheri [11]

F. rectangularis [11] F. serratula [11] F. tenax [11] Fistulipora F. introspinosa [1][11] Glyptopora G. crassa [1][11] G. michilinia [1][11] Lyropora L. solida [1][11] Meekopora M. abrupta [1][11] M. tenuis [1][11] Polypora P. whitei [1]

Rhombopora [1] Septopora S. biserialis [1] S. cestriensis [1] S. subquadrans [1] Tabulopora T. cestriensis [1][11] T. microfistulata [1][11] T. poculoformis [1][11] T refiexa [1][11] T. subtilis [1][11]

A Devonian Fenestella from Belgium.

Brachiopoda

Athyris A. cestriensis Buxtonia B. arkansana Camarophoria C. cestriensis C explanata Chonetes C. oklahomensis C. sericeus C. tumescens Cliothyridina C. sublamellosa Composita (See unidentified section) C. subquadrata C. trinuclea

Crania C. infimbriata Diaphragmus Dielasma D. arkansanum D. formosum D. illinoisensis D. shumardanum D. whitfieldi Echinoconchus (See unidentified section) E. alternatus Eumetria E. costata E. pitkinensis E. vera Girtyella G. indianensis

Hustedia H. multicostata Krotavia K. lucerna Lingula Lingulidiscina L. newberryi var. moorefieldana and ovata Linoproductus L. pileiformis Martinia Orthotetes O. kaskaskiensis O. stenopsis[12] O. subglobosus (var. protensa) O. uspectum Productus P. cestriensis P. fasciculatus

Pustula Reticularia R. setigera Spirifer S. leidyi S. pellaensis Spiriferina S. spinosa Streptorhynchus Syringothyris S. aequalis Tetracamera T. neogenes

Bivalvia, Bivalves

This group was also referred to by another name in earlier studies: Pelecypoda.[1]

Allorisma A. walkeri Astartella Aviculopecten A. batesvillensis A. eurekensis A. keoughensis A. morrowensis A. multilineatus A. pitkinensis Conocardium C. peculiare

Cypricardella (See unidentified section) Edmondia E. crassa (Along with E. crassa var. suborbiculoidea) E. pitkinensis Leda L. vaseyana Leiopteria Leptodesma

Myalina M. compressa M. longicardinalis Nucula N. illinoisensis Parallelodon Pteronites Schizodus (See unidentified section) S. arkansanus S. chesterensis S. depressus S. insignis

Solenomya Sphenotus S. cherokeense S. gibsonense S. quadriplicatum

Scaphopoda, Tusk Shells

• Laevidentalium

Gastropoda, Snails

Bellerophon (See unidentified section) B. pitkinensis Bucanella Colpites Euphemites E. incarinatus Clabrocingulum Gosseletina (See unidentified section)

Helcionopsis H. reticulatus Hemizyga Holopea H. newtonensis Latischisma Leptoptygma (See unidentified section) Microptychis

Mourlonia M. angulata Naticopsis Neilsonia Phanerotremas Platyceras P. subrotundum Pseudozygopleura

Sphaerodoma S. subcorpulenta Stegocoelia Straparolus S. planidorsatus S. triliris Strobeus (See unidentified section) Strophostylus

Cephalopoda

Arcanoceras A. furnishi[13] Coloceras (see unidentified section) Cravenoceras C. hesperium C. richardsonianum[13] Cycloceras C. randolphensis C. equoyahensis Dolorthoceras (See unidentified section) D. eurekensis

Eoasianites E. globosus Eumorphoceras E. bisulcatum[13] Metadimorphoceras[13] Mooreoceras Syngastrioceras[13] Trizonoceras[13]

Trilobita

• Grifithides

G. pustulosus

• Kaskia

K. chesterensis

K. pitkinensis[14]

• Paladin

P. mucronatus

Ostracoda

• Glyptopleurain

G. optina

• Paraparchites
• Primitia

P. fayettevillensis

Vertebrata

• Cladodus
• Deltodus
• Petalodus

Plantae, Plants

"Encrusting Algae" has been reported but not assigned to any genus.[1]

• Archaeolithophyllum[6]
• Asphaltina

A. cordillerensis[5]

• Girvanella[5]
• Rectangulina[5]

Unidentified

Following is a list of fossils also found in the Pitkin by Easton in 1943 that have gone unidentified.[1]

• A "Cup Coral"
• A member of the genus Pentremites
• Three species within Agassizocrinus
• Two species within Scytalocrinus
• A totally unidentifiable Crinoid
• Two species of Bellerophon
• Two species of Gosseletina
• Two species of Leptoptygma
• Two Species of Strobeus
• One species each of Composita and Echinoconchus
• Two species of Cypricardella
• Two species of Coloceras, one of which may actually be Leuroceras
• One species of Dolorthoceras
• An unnamed shark spine

See also

• List of fossiliferous stratigraphic units in Arkansas
• Paleontology in Arkansas

References

1. Easton, William H., The Fauna of the Pitkin Formation of Arkansas., Journal of Paleontology: vol. 17:2. March, 1943.
2. McFarland, John David (2004) [1998]. "Stratigraphic summary of Arkansas" (PDF). Arkansas Geological Commission Information Circular. 36: 12–13. Archived from the original (PDF) on 2016-12-21. Retrieved 2018-05-31.
3. Adams, G.; Ulrich, E. (1904). "Zinc and lead deposits of northern Arkansas". U.S. Geological Survey Professional Paper. 24: 27, 109.
4. Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to thefix Paleobiology Database". Archived from the original on 31 July 2014. Retrieved 8 July 2014.
5. Brenckle, Paul (1977). "Foraminifers and other calcareous microfossils from Late Chesterian (Mississippian) strata of northern Arkansas" (PDF). Oklahoma Geological Survey Guidebook. 18: 73–87. Retrieved 3 February 2018.
6. Nodine-Zeller, Doris E. (1977). "Microfauna from Chesterian (Mississippian) and Morrowan (Pennsylvanian) rocks in Washington County, Arkansas, and Adair and Muskogee Counties, Oklahoma" (PDF). Oklahoma Geological Survey Guidebook. 18: 89–99. Retrieved 3 February 2018.
7. Webb, Gregory., 1987., The Coral Fauna of the Pitkin Formation (Chesterian), Northeastern Oklahoma and Northwestern Arkansas. Journal of Paleontology vol. 61:3
8. Webb., Gregory., 1990., A New Tabulate Coral Species from the Pitkin Formation (Chesterian) of north-central Arkansas. Journal of Paleontology vol. 64:4.
9. Horowitz, Alan S.; Macurda Jr, D. B. (1977). "Late Mississippian and Early Pennsylvanian blastoids from northeastern Oklahoma and northwestern Arkansas" (PDF). Oklahoma Geological Survey Guidebook. 18: 169–170. Retrieved 31 January 2018.
10. Strimple, Harrell L. (1977). "Chesterian (Upper Mississippian) and Morrowan (Lower Pennsylvanian) crinoids of northeastern Oklahoma and northwestern Arkansas" (PDF). Oklahoma Geological Survey Guidebook. 18: 171–176. Retrieved 30 January 2018.
11. Horowitz, Alan S. (1977). "Late Mississippian and Early Pennsylvanian bryozoan faunas of Arkansas and Oklahoma: a review" (PDF). Oklahoma Geological Survey Guidebook. 18: 101–105. Retrieved 3 February 2018.
12. Henry, Thomas W.; Gordon Jr., Mackenzie (January 1985). "Chesterian davidsoniacean and orthotetacean brachiopods, Ozark region of Arkansas and Oklahoma". Journal of Paleontology. 59 (1): 32–59. JSTOR 1304826.
13. Saunders, W. Bruce; Manger, Walter L.; Gordon Jr., Mackenzie (1977). "Upper Mississippian and Lower and Middle Pennsylvanian ammonoid biostratigraphy of northern Arkansas" (PDF). Oklahoma Geological Survey Guidebook. 18: 117–137. Retrieved 1 February 2018.
14. Brezinski, David K. (31 March 2017). "Some New Late Mississippian Trilobites from Oklahoma and Arkansas". Annals of Carnegie Museum. 84 (2): 173–178. doi:10.2992/007.084.0203.