Campito Formation

Campito Formation
Campito Formation
Stratigraphic range: Lower Cambrian PreꞒ Ꞓ O S D C P T J K Pg N
	White Mountains mousetails, growing on substrate within the Campito Formation
Type	Formation
Sub-units	See: Members
Underlies	Poleta Formation
Overlies	Deep Spring Formation
Thickness	0–3,500 ft (0–1,067 m)
Lithology
Primary	Quartzite
Other	Siltstone, Sandstone
Location
Region	California, Nevada
Country	United States

Last updated December 26, 2025

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

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

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

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

Genus	Species	Notes
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]^[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

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

Lophotrochozoa

Genus	Species	Notes
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

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

Cnidaria

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

Porifera (Sponges)

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

Echniodermata

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

Foraminifera

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

incertae sedis

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

Ichnogenera

Genus	Species	Notes
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.

References

1 2 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.
1 2 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.
1 2 3 4 5 6 7 8 9 10 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.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 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.
1 2 3 4 5 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.
1 2 3 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.
1 2 3 4 Firby, Jean B.; Durham, J. Wyatt (1974). "Molluscan Radula from Earliest Cambrian". Journal of Paleontology. 48 (6): 1109–1119. ISSN 0022-3360.
1 2 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.
1 2 3 4 5 6 7 8 9 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.
1 2 3 4 5 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.
↑ 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.
1 2 3 4 5 6 7 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.
1 2 3 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.
↑ Tynan, Mark C. (1983). "Coral-like Microfossils from the Lower Cambrian of California". Journal of Paleontology. 57 (6): 1188–1211. ISSN 0022-3360.
↑ 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.
↑ 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.

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[Pruss2025-1] 1 2 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.

[McKee-2] 1 2 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.

[Stewart1970-3] 1 2 3 4 5 6 7 8 9 10 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.

[Alpert1976-4] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 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.

[Stewart2007-5] 1 2 3 4 5 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.

[Lieberman_2002-6] 1 2 3 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.

[Firby1974-7] 1 2 3 4 Firby, Jean B.; Durham, J. Wyatt (1974). "Molluscan Radula from Earliest Cambrian". Journal of Paleontology. 48 (6): 1109–1119. ISSN 0022-3360.

[Signor1988-8] 1 2 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.

[Stewart2005-9] 1 2 3 4 5 6 7 8 9 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.

[Hollingsworth2006-10] 1 2 3 4 5 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.

[Wotte2017-12] 1 2 3 4 5 6 7 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.

[Rowell1977-13] 1 2 3 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.

[Tynan1983-14] 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.

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