"Trilobite zone", Ross Formation, sec. 1A (Devonian of the United States)

Where: Tennessee (36.0° N, 88.0° W: paleocoordinates 36.6° S, 48.2° W)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Birdsong Shale Member (Ross Formation), Gedinnine (416.0 - 412.3 Ma)

• Sampled zone only 2.5 feet thick, but bluff 160 yards long (approx. 9-11.5 feet from top of formation, of which 22.5 feet are exposed). Listed as Gedinnian

• group of beds-level stratigraphic resolution

Environment/lithology: offshore shelf; poorly lithified, shelly/skeletal, blue, argillaceous, calcareous shale and lithified, calcareous wackestone

• Background sedimentation with obrution deposits and tempestites in low energy, muddy environment
• Highly fossiliferous, soft, bluish, calcareous clay shale occasionally interbedded with limestone (packstones and wackestone)

Size classes: macrofossils, mesofossils

Primary reference: C.O. Dunbar. 1919. Stratigraphy and correlation of the Devonian of western Tennessee. Geological Survey Tennessee, Bulletin 21:1-127 [G. Webster/G. Webster]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 75628: authorized by Phil Novack-Gottshall, entered by Paul Hearn on 23.10.2007

Creative Commons license: CC BY (attribution)

Taxonomic list

Anthozoa
 Favositida - Favositidae
Favosites conicus tabulate coral
Crinoidea
 Disparida - Synbathocrinidae
Phimocrinus sp. n. sp. Schultze 1867 Sea lily
Strophomenata
 Strophomenida - Leptaenoideidae
 Strophomenida - Strophonellidae
 Strophomenida - Leptostrophiidae
 Strophomenida - Rafinesquinidae
Leptaena rhomboidalis Wahlenberg 1818
Rhynchonellata
 Orthida - Orthidae
 Orthida - Dalmanellidae
"Dalmanella pygmaea" = Isorthis pygmaea Dunbar 1919
 Orthida - Rhipidomellidae
"Rhipidomella oblata" = Rhipidomelloides oblata Hall 1857
 Orthida - Dicoelosiidae
"Bilobites varicus" = Dicoelosia varica
"Bilobites varicus" = Dicoelosia varica Conrad 1842
 Spiriferida - Delthyrididae
 Athyridida - Rhynchospirinidae
"Rhynchospira formosa" = Rhynchospirina
"Rhynchospira formosa" = Rhynchospirina
 Athyridida - Meristellidae
 Athyridida - Anoplothecidae
 Atrypida - Atrypinidae
 Rhynchonellida - Eatoniidae
 Rhynchonellida - Uncinulidae
Trilobita
 Phacopida - Phacopidae
"Phacops logani" = Paciphacops logani
"Phacops logani" = Paciphacops logani Hall 1860 trilobite
"Common"