T-4: T(A) Cascade Spr. (Triassic of the United States)

Where: Utah (40.0° N, 111.0° W: paleocoordinates 9.5° N, 36.2° W)

• coordinate based on nearby landmark

• small collection-level geographic resolution

When: Thaynes Formation, Spathian (251.3 - 247.2 Ma)

• Most recently, the Thaynes formation has been separated into four facies belts, which include a basinal facies, an outer shelf facies, an inner shelf facies, and a red bed facies. the basinal facies consists of dark grey to black very siltly lime mudstones and gray to loive drab siltstones and shales. The outer shelf facies belt is characterized by dark grayish brown whole fossil wackestone, ranging to light gray bioclastic grainstone, with minor interbedded sanstone, siltstone, and mudstone. The inner shelf facies includes a variety of lithologies, mainly fine-grained mudstone and silty limestone, along with less common dolomite, siltstone, and bioturbated mudstone.

• group of beds-level stratigraphic resolution

Environment/lithology: marine; lithified packstone

• low-relief shell banks or amalgamated shell beds, subject to wave action. these massive bioclastic packstones are dominated by nested large bivavles and bivalve fragments, held in a micrite matrix without any preferential orientation.

Size class: macrofossils

Primary reference: J. K. Schubert and D. J. Bottjer. 1995. Aftermath of the Permian-Triassic mass extinction event: Paleoecology of Lower Triassic carbonates in the western USA. Palaeogeography, Palaeoclimatology, Palaeoecology 116:1-39 [D. Bottjer/N. Bonuso/N. Bonuso]more details

Purpose of describing collection: paleoecologic analysis

PaleoDB collection 32972: authorized by David Bottjer, entered by Nicole Bonuso on 21.07.2003

Creative Commons license: CC BY (attribution)

Taxonomic list

Gastropoda
 Caenogastropoda - Coelostylinidae
Omphaloptychia sp. von Ammon 1893 snail
 Trochoidea - Colloniidae
Chartronella sp. Cossman 1902 snail
Bivalvia
 Myalinida - Myalinidae
Promyalina sp. Kittl 1903 clam
Echinoidea
 Cidaroida - Miocidaridae
Miocidaris sp. Döderlein 1887 pencil urchin
Crinoidea
 Holocrinida - Holocrinidae
Holocrinus sp. Wachsmuth and Springer 1886 Sea lily