Pitkin Formation

Pitkin Formation Stratigraphic range: Carboniferous (Serpukhovian and Upper Visean)[1]
Type	Formation
Sub-units	none
Underlies	Hale Formation
Overlies	Fayetteville Formation
Lithology
Primary	Limestone[1]
Location
Region	Arkansas
Country	United States

The Pitkin Formation is a geologic formation in Arkansas. It preserves fossils dating back to the Carboniferous period.^[2]

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

• Endothyra

Porifera, Sponges

• Cliona

Scyphozoa

• Conularia Originally considered to be a gstropod.

Anthozoa, Corals

Amplexus Aulopora A. gracilis Caninostrotion C. variablilis Kinkaidia[3] Lesliella [3] Leonardophyllum[3]

Lonsdaleia L. major L. minor Michellinia [4] M. macerimuris[4] Parvaxon [3] Pleurodictyum P. eugenei P. meekanum Syringopora Triplophyllum

Blastoidea

• Pentremites

P. laminatus

P. platybasis

Crinoidea, Sea Lilies

Agassizocrinus (see unidentified section) Carcinocrinus C. stevensi Castillocrinus Cosmetocrinus Cromyocrinus Cyathocrinus Delocrinus

Hydreionocrinus Linocrinus L. floweri Pachylocrinus Pelecocrinus P. stereostoma Phanocrinus P. cooksoni

Poteriocrinus Pterotocrinus Scytalocrinus (see unidentified section) S. braggsi S. dunlapi S. garfieldi

Ophiuroidea, Brittle Stars

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

• Aganaster

A. singulatus

• Schoenaster

Echinoidea, Sea Urchins

• Archaeocidaris

Worms

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

• Spirorbis

Bryozoa, "Moss-animals"

Anisotrypa A. solida Archimedes (called Archimedipora in early studies) [1] A. communis A. distans A. intermedia A. invaginata A. proutana A. swallovana Batostomella Chilotrypa C. regularis

Dichotrypa D. levis Dyscritella Fenestella Fistulipora F. introspinosa Glyptopora G. michilinia G. crassa Lyropora L. solida

Meekopora M. abrupta M. tenuis Polypora P. whitei Rhombopora Septopora S. biserialis S. cestriensis S. subquadrans

Tabulopora T. cestriensis T. microfistulata T. poculoformis T refiexa T. subtilis

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.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

• Coloceras (see unidentified section)
• Cravenoceras

C. hesperium

• Cycloceras

C. randolphensis

C. equoyahensis

• Dolorthoceras (See unidentified section)

D. eurekensis

• Eoasianites

E. globosus

• Mooreoceras

Trilobita

• Grifithides

G. pustulosus

• Kaskia

K. chesterensis

• 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]

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. Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to thefix Paleobiology Database". Retrieved 8 July 2014.
3. Webb, Gregory., 1987., The Coral Fauna of the Pitkin Formation (Chesterian), Northeastern Oklahoma and Northwestern Arkansas. Journal of Paleontology vol. 61:3
4. Webb., Gregory., 1990., A New Tabulate Coral Species from the Pitkin Formation (Chesterian) of north-central Arkansas. Journal of Paleontology vol. 64:4.