Pitkin Formation

Geologic formation in Arkansas, United States From Wikipedia, the free encyclopedia

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 shales at the top of the Pitkin Formation to be a separate formation called the Imo Formation. More recently, others have considered the Imo to be informal member of the Pitkin Formation.

TypeFormation
Sub-unitsImo Shale
UnderliesHale Formation
OverliesFayetteville Formation
Quick facts Type, Sub-units ...
Pitkin Formation
Stratigraphic range: Upper Visean-Serpukhovian[1]
TypeFormation
Sub-unitsImo Shale
UnderliesHale Formation
OverliesFayetteville Formation
Thicknessup to and over 400 feet[2]
Lithology
PrimaryLimestone[1]
OtherShale
Location
RegionArkansas
CountryUnited States
Type section
Named forPitkin post office, Washington County, Arkansas[3]
Named byGeorge Irving Adams and Edward Oscar Ulrich
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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.'

Foraminifera

  • Archaediscus
A. stilus[5]
  • Asteroarchaediscus
A. rugosus[5]
E. kleina[6]
E. phrissa[5]
  • Endothyranella[6]
  • Eosigmoilina
E. explicata[5]
E. rugosa[5]
P. priscus[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.

Scyphozoa

  • Conularia Originally considered to be a gastropod.

Anthozoa, Corals

A. gracilis
  • Caninostrotion
C. variablilis
  • Kinkaidia[7]
  • Lesliella[7]
  • Leonardophyllum[7]
  • Lonsdaleia
L. major
L. minor
M. macerimuris[8]
P. eugenei
P. meekanum

Blastoidea

Pentremites godoni from the Lower Carboniferous of Illinois.
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]
L. floweri[10]
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]
S. braggsi[10]
S. dunlapi[10]
S. garfieldi[10]
T. whitfieldi[10]
  • Telikosocrinus
T. caespes
T. residuus
  • Zeusocrinus
Z. foveatus

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.

Worms

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

Bryozoa, "Moss-animals"

Quick facts Stereo image, Left frame ...
Stereo image
Left frame 
Right frame 
Parallel view ()
Cross-eye view ()
Fossilized skeleton of Archimedes Bryozoan.
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  • Anisotrypa
A. solida [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]
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]
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

  • Adectorhynchus
A. suspectum [12]
A. cestriensis
  • Buxtonia
B. arkansana
  • Camarophoria
C. cestriensis
C explanata
C. oklahomensis
C. sericeus
C. tumescens
Cliothyridina
  • C. sublamellosa
  • Composita (See unidentified section)
C. subquadrata
C. trinuclea
C. infimbriata
D. arkansanum
D. formosum
D. illinoisensis
D. shumardanum
D. whitfieldi
E. alternatus
  • Eumetria
E. costata
E. pitkinensis
E. vera
  • Girtyella
G. indianensis
  • Hustedia
H. multicostata
  • Krotavia
K. lucerna
L. newberryi var. moorefieldana and ovata
L. pileiformis
O. kaskaskiensis
O. stenopsis[12]
O. subglobosus (var. protensa)
O. uspectum
P. cestriensis
P. fasciculatus
R. setigera
S. leidyi
S. pellaensis
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
A. batesvillensis
A. eurekensis
A. keoughensis
A. morrowensis
A. multilineatus
A. pitkinensis
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
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

Gastropoda, Snails

E. incarinatus
  • Clabrocingulum
  • Gosseletina (See unidentified section)
  • Helcionopsis
H. reticulatus
H. newtonensis
  • Latischisma
  • Leptoptygma (See unidentified section)
  • Microptychis
  • Mourlonia
M. angulata
P. subrotundum
  • Pseudozygopleura
  • Sphaerodoma
S. subcorpulenta
  • Stegocoelia
  • Straparolus
S. planidorsatus
S. triliris
  • Strobeus (See unidentified section)
  • Strophostylus

Cephalopoda

A. furnishi[13]
C. hesperium
C. richardsonianum[13]
C. randolphensis
C. equoyahensis
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]
P. mucronatus

Ostracoda

  • Glyptopleurain
G. optina
  • Paraparchites
  • Primitia
P. fayettevillensis

Vertebrata

Plantae, Plants

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

A. cordillerensis[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

References

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