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Campito Formation
Stratigraphic range: Lower Cambrian [1]
White Mountains mousetails, growing on substrate within the Campito Formation
TypeFormation
Sub-unitsSee: Members
UnderliesPoleta Formation[2]
OverliesDeep Spring Formation[2]
Thickness0–3,500 ft (0–1,067 m)[3]
Lithology
PrimaryQuartzite
OtherSiltstone, Sandstone
Location
RegionCalifornia, Nevada
CountryUnited States

The Campito Formation is a geologic formation in the Last Chance Range, California, and Esmeralda County, Nevada. It preserves fossils dating back to the Cambrian period.

Geology

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The Campito Formation is mainly composed of very fine to fine-grained quartzite, with small amounts of siltstone, getting up to 3,500 ft (1,100 m) thick.[3]

Members

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The formation is split into two distinct members, which are as follows, in ascending age:

  • Andrews Mountain Member: It is the thickest of the two members, getting up to 2,800 ft (850 m) thick. It is composed of olive-gray or greenish-gray very fine to fine grained silty quartzitic sandstone or quartzite and interbedded layers of dark-greenish-gray siltstones, which weather to a greenish-black or just black. The quartzite layers are composed of sub-angular very fine to fine grains of quartz, feldspar and other metallic minerals, all set within a muscovite, chlorite, and biotite.[3]
  • Montenegro Member: It is the thinnest of the two members, only getting up to 1,000 ft (300 m) thick. It is composed of dark-greenish-gray and greenish-gray siltstone composed of a mixture of quartz, muscovite, and chlorite. The siltstone is evenly laminated to thin-bedded. There are also commonly occurring archeocyathid-bearing limestone beds in the upper sections of the member.[3]

Paleobiota

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The Campito Formation contains a number of fossils, most of which are found within the Montenegro Member. They range from archeocyathid sponges like Ethmophyllum, to arthropod trilobites like Nevadia,[3] and a wealth of ichnogenera, from burrows like Skolithos, to resting traces like Rusophycus.[4]

Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Arthropoda

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Genus Species Notes Images
Fritzaspis[5]
  • Fritzaspis sp.
  • F. generalis
  • F. ovalis
 Fallotaspidoid trilobite.
Amplifallotaspis[5]
  • A. keni
 Fallotaspidoid trilobite.
Profallotaspis (?)[5]
  • Profallotaspis (?) sp.
 Fallotaspidoid trilobite.
Archaeaspis[6]
  • A. nelsoni
  • A. macropleuron
 Fallotaspidoid trilobite.
Cirquella[6]
  • C. nelsoni
 Fallotaspidoid trilobite.
Cambroinyoella[6]
  • C. wallacei
 Fallotaspidoid trilobite.
Fallotaspis[3][7][8][9]
  • Fallotaspis sp.
  • F. longa
 Fallotaspidoid trilobite.
Daguinaspis[3]
  • Daguinaspis sp.
 Fallotaspidoid trilobite.
Repinaella[9][5]
  • Repinaella sp.
 Fallotaspidoid trilobite.
Eofallotaspis[9]
  • Eofallotaspis sp.
 Fallotaspidoid trilobite.
Nevadia[3]
  • Nevadia sp.
 Nevadiid trilobite.
Judomia (?)[3]
  • Judomia (?) sp.
 Nevadiid trilobite, assignment to genus is very tentative.
Montezumaspis[10]
  • M. parallela
  • M. cometes
 Holmiid trilobite.
Esmeraldina[3][10][9]
  • E. rowei
  • E. elliptica
  • E. cometes (?)
 Holmiid trilobite. E. cometes was previously identified as Fallotaspis tazemmourtensis.[9]
Holmiella[10]
  • Holmiella sp.
  • H. millerensis
 Holmiid trilobite.
Palmettaspis[10]
  • P. consorta
  • P. lidensis
 Holmiid trilobite.
Grandinasus[10]
  • G. auricampus
  • G. patulus
 Holmiid trilobite.

Lobopodia

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Genus Species Notes Images
Microdictyon[11][12]
  • Microdictyon sp.
 Xenusid lopopod.

Lophotrochozoa

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Genus Species Notes Images
Microcornus[12]
  • Microcornus sp.
 Lophotrochozoan hyolith.
Ladatheca[9]
  • Ladatheca sp.
 Lophotrochozoan hyolith.
Parkula[12]
  • Parkula sp.
 Lophotrochozoan hyolith.
Hyolithellus (?)[12]
  • Hyolithellus (?) sp.
 Lophotrochozoan hyolith.
Obolella[13]
  • O. excelsis
 Obelellid brachiopod.
Pelagiella[12]
  • P. subangulata
 Pelagiellid mollusc.
Nisusia (?)[13][9]
  • Nisusia (?)sp.
 Kutorginid brachiopod.
Sabellidites (?)[9]
  • Sabellidites (?) sp.
 Tubular fossil.
Brachiopod indet.[13]
  • ???
 Indeterminate brachiopod, most likely an internal mold, possibly a poorly preserved Nisusia (?)sp. specimen, or another kutorginid brachiopod.
Obelellid molds[9]
  • ???
 Molds of obelellid brachiopods.

Chancelloriidae

[edit]
Genus Species Notes Images
Allonia[12]
  • Allonia sp.
 Chancelloriid organism.
Chancelloria[12]
  • Chancelloria sp.
 Chancelloriid organism.


Cnidaria

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Genus Species Notes Images
Paiutitubulites[14]
  • P. variabilis
 Anthozoan cnidarian.

Porifera (Sponges)

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Genus Species Notes Images
Ethmophyllum (?)[1]
  • Ethmophyllum (?) sp.
 Archeocyathid sponge.

Echniodermata

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Genus Species Notes Images
Helicoplacus[7]
  • Helicoplacus sp.
 Oblong echinoderm.
Isolated plates[15]
  • Eocrinoidea (?)
 Isolated plates, possibly of eocrinoid origin.

Foraminifera

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Genus Species Notes Images
Platysolenites[7]
  • P. antiquissimus
 Agglutinated hyperamminid foraminiferan.

incertae sedis

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Genus Species Notes Images
Onuphionella[8]
  • O. durhami
 Tubular fossil.
Volborthella[16]
  • V. titanius
 Tubular fossil, originally described as Campitius.[7]

Ichnogenera

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Genus Species Notes Images
Cruziana[4]
  • Cruziana sp.
 Trails.
Planolites[4]
  • Planolites sp.
 Burrows.
Helminthopsis[4]
  • Helminthopsis sp.
 Feeding trails.
Belorhaphe[4]
  • Belorhaphe sp.
 Burrows.
Cochlichnus[4]
  • Cochlichnus sp.
 Burrows.
Scolicia[4]
  • Scolicia sp.
 Burrows.
Rusophycus[4]
  • R. didymus
  • R. radwanskii
 Resting trace of trilobites.
Bergaueria[4]
  • Bergaueria sp.
 Resting trace of cnidarians.
Zoophycus[4]
  • Zoophycus sp.
 Polychaete feeding traces.
Arthrophycus[4]
  • Arthrophycus sp.
 Polychaete trace.
Teichichnus[4]
  • Teichichnus sp.
 Feeding trace.
Treptichnus[4]
  • Treptichnus sp.
 Burrow, originally described as Phycodes.
Diplichnites[4]
  • Diplichnites sp.
 Arthropod trackways.
Skolithos[4]
  • Skolithos sp.
 Burrows.

See also

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References

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  1. ^ a b Pruss, Sara B.; Smith, Emily F.; Zhuravlev, Andrey Yu; Nolan, Rhiannon Z.; McGann, Tessa C. (June 2025). "Rise and fall of archaeocyath reefs shaped early Cambrian skeletal animal abundance". Palaeogeography, Palaeoclimatology, Palaeoecology. 667 112852. doi:10.1016/j.palaeo.2025.112852.
  2. ^ a b Edwin H. McKee (1968). "Geology of the Magruder Mountain area, Nevada-California" (PDF). U.S. Geological Survey Bulletin: H7. doi:10.3133/B1251H. ISSN 8755-531X. Wikidata Q57805921.
  3. ^ a b c d e f g h i j Stewart, J. H. "Upper Precambrian and Lower Cambrian Strata, in the Southern Great Basin California and Nevada" (PDF). U.S. Geological Survery. Geological Survey Professional.
  4. ^ a b c d e f g h i j k l m n o Alpert, Stephen P. (1976). "Trilobite and Star-like Trace Fossils from the White-Inyo Mountains, California". Journal of Paleontology. 50 (2): 226–239. ISSN 0022-3360.
  5. ^ a b c d Stewart, H. J. (2007). "Fallotaspidoid trilobite assemblage (Lower Cambrian) from the Esmeralda Basin (western Nevada, U.S.A.): The oldest trilobites from Laurentia". Alcheringa: An Australasian Journal of Palaeontology. 31: 123–140. doi:10.1080/03115510701586897.
  6. ^ a b c Lieberman, B.S. (2002). "Phylogenetic analysis of some basal early Cambrian Trilobites, the biogeographic origins of the Eutrilobites, and the timing of the Cambrian radiation" (PDF). Journal of Paleontology. 76 (4): 692–708. doi:10.1666/0022-3360(2002)076<0692:paosbe>2.0.co;2. Archived from the original (PDF) on 2011-08-12. Retrieved 2012-08-14.
  7. ^ a b c d Firby, Jean B.; Durham, J. Wyatt (1974). "Molluscan Radula from Earliest Cambrian". Journal of Paleontology. 48 (6): 1109–1119. ISSN 0022-3360.
  8. ^ a b Signor, Philip W.; Mcmenamin, Mark A. S. (March 1988). "The Early Cambrian worm tube Onuphionella from California and Nevada". Journal of Paleontology. 62 (2): 233–240. doi:10.1017/S0022336000029863.
  9. ^ a b c d e f g h i Stewart Hollingsworth, J. (May 2005). "The earliest occurrence of trilobites and brachiopods in the Cambrian of Laurentia". Palaeogeography, Palaeoclimatology, Palaeoecology. 220 (1–2): 153–165. doi:10.1016/j.palaeo.2004.08.008.
  10. ^ a b c d e Hollingsworth, J. Stewart (2006). "Holmiidae (Trilobita: Olenellina) of the Montezuman Stage (Early Cambrian) in Western Nevada". Journal of Paleontology. 80 (2): 309–332. ISSN 0022-3360.
  11. ^ Skovsted, Christian B.; Balthasar, Uwe; Vinther, Jakob; Sperling, Erik A. (May 2021). "Small shelly fossils and carbon isotopes from the early Cambrian (Stages 3–4) Mural Formation of western Laurentia". Papers in Palaeontology. 7 (2): 951–983. doi:10.1002/spp2.1313.
  12. ^ a b c d e f g Wotte, Thomas; Sundberg, Frederick A. (2017). "Small shelly fossils from the Montezuman–Delamaran of the Great Basin in Nevada and California". Journal of Paleontology. 91 (5): 883–901. ISSN 0022-3360.
  13. ^ a b c Rowell, A. J. (1977). "Early Cambrian Brachiopods from the Southwestern Great Basin of California and Nevada". Journal of Paleontology. 51 (1): 68–85. ISSN 0022-3360.
  14. ^ Tynan, Mark C. (1983). "Coral-like Microfossils from the Lower Cambrian of California". Journal of Paleontology. 57 (6): 1188–1211. ISSN 0022-3360.
  15. ^ Ubaghs, Georges (May 1975). "Early Paleozoic Echinoderms". Annual Review of Earth and Planetary Sciences. 3 (1): 79–98. doi:10.1146/annurev.ea.03.050175.000455.
  16. ^ Yochelson, Ellis L.; Kisselev, Gennadii N. (March 2003). "Early Cambrian Salterella and Volborthella (Phylum Agmata) re‐evaluated". Lethaia. 36 (1): 8–20. doi:10.1080/00241160310001254.