Buelna Fm., Cerro Rajon, Caborca Region, Mexico - Stewart et. al 1984 (Cambrian of Mexico)

Where: Mexico (30.4° N, 111.9° W: paleocoordinates 4.3° S, 102.8° W)

When: Buelna Formation (Bonnia-Olenellus Group), Dyeran (515.3 - 511.2 Ma)

• All lithology/stratigraphic details are based primarily on exposures of rocks in the Cerro Rajon area. Unit is 77.5m thick. Formation creates a conspicuous ridge or ledge in most areas. The broad facies included in the formation and a lack of information regarding the lithology containing the fossils prevents a single paleoenvironment from being selected.

• group of beds-level stratigraphic resolution

Environment/lithology: lithified, gray, green, yellow siltstone and lithified, brown, yellow sandstone

• Represents a southern extension of the Cordilleran miogeocline, rocks may be offset 700 to 800km along a left- lateral fault.
• Mixed rock types. Siltstone, greenish gray to yellowish gray, coarse silt. Quartzite, yellowish brown, fine to medium grained, laminated and cross stratified. Limestone and dolomite, sandy in parts, light-gray, commonly weathering moderate brown, laminated and cross stratified.

Size classes: macrofossils, mesofossils

Preservation: trace, original calcite

Collection methods: bulk,

Primary reference: J. Stewart, M. A. S. McMenamin, and J. M. Morales-Ramirez. 1984. Upper Proterozoic and Cambrian rocks in the Caborca Region, Sonora, Mexico - physical stratigraphy, biostratigraphy, paleocurrent studies, and regional relations. U. S. Geological Survey Professional Papers (1309)1-33 [M. Patzkowsky/P. Borkow]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 10684: authorized by Mark Patzkowsky, entered by Phil Borkow on 11.06.2001

Creative Commons license: CC BY (attribution)

Taxonomic list

 Archaeocyathida - Archaeopharetridae
Protopharetra sp. Bornemann 1884 archaeocyath sponge
 Capsulocyathida - Coscinocyathidae
Coscinocyathus sp. Bornemann 1884 archaeocyath sponge
  - Salterellidae
Salterella sp. Billings 1861
Salterella maccullochi
  - Salterellidae
Salterella maccullochi Murchison 1859
Salterella pulchella
  - Salterellidae
  - Antagmidae
Onchocephalus mexicanus Lochman 1952 trilobite
Onchocephalus buelnaensis Lochman 1952 trilobite
Sombrerella mexicana Lochman 1948 trilobite
Antagmus buttsi Resser 1939 trilobite
Antagmus solitarius Lochman 1952 trilobite
 Redlichiida -
Olenelloidea indet. Walcott 1890 trilobite
 Redlichiida - Wanneriidae
Wanneria sp. Walcott 1910 trilobite
Wanneria walcottana Wanner 1901 trilobite
 Redlichiida - Olenellidae
Olenellus puertoblancoensis Lochman 1952 trilobite
"Olenellus fremonti" = Mesonacis fremonti Walcott 1910 trilobite
 Corynexochida - Dorypygidae
Bonnia sonora Lochman 1952 trilobite
 Scenelloidea - Scenellidae
 Paterinida - Paterinidae
Paterina sp. Beecher 1891
 Hyolithida - Hyolithidae
Hyolithes sp., "Hyolithes whitei" = Nevadotheca whitei
Hyolithes sp. d'Eichwald 1840
"Hyolithes whitei" = Nevadotheca whitei Resser 1938
 Orthothecida - Orthothecidae
Orthotheca buelna Lochman 1952
 Oscillatoriales - Girvanellaceae
Girvanella sp. Nicholson and Etheridge 1878
Girvanella mexicana Cooper et al. 1952
 Ichnofossils -
Palaeophycus sp. Hall 1847
trace fossil
Cruziana sp. d'Orbigny 1842
trace fossil