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Mule Spring Limestone
Stratigraphic range: Lower Cambrian [1]
TypeFormation
Underlies
Overlies
Thickness0–1,000 feet (0–305 m)[1]
Lithology
PrimaryLimestone
OtherSiltstone, Shale,
Location
RegionMojave Desert, California, Nevada
CountryUnited States

The Mule Spring Limestone is a geologic formation in the Saline Range of eastern California and Split Mountain and Goldfield Hills of Nevada.

It is also to be found in the Inyo Mountains and White Mountains.

It preserves fossils, such as trilobites, and algal structures like Girvanella, dating back to the Cambrian period.[2][1]

Geology

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The Mule Spring Limestone, as its name suggests, is mainly composed of limestone rocks. These rocks are medium-gray to light-medium-gray, as well as very fine to fine crystalline, and is thin to very thin-bedded in most areas. In the lower sections of the formation, there are also occasional layers, up to 500 ft (150 m) thick, of pale-yellowish-brown or greenish-gray shale, limy siltstone and silty limestone.[1] In the Split Mountain, the formation overlies the Harkless Formation and underlies the Emigrant Formation,[1][3] whilst in other areas it overlies the Saline Valley Formation and underlies the Monola Formation.[1]

Paleobiota

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The Mule Spring Limestone contains examples of Archaeocyatha, a clade of sponges that went extinct during this time,[4] as well as a collection of trilobites.[2][1]

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
Bristolia[1][2][5][3]
  • Bristolia sp.
  • B. harringtoni
  • B. insolens
  • B. bristolensis
  • B. anteros
  • B. fragilis
 Biceratopsid trilobites.
Peachella[1][2][5]
  • Peachella sp.
 Biceratopsid trilobite.
Mesonacis[2]
  • Mesonacis sp.
 Olenellid trilobite. Mesonacis sp. previously described as Fremontia sp. which was later synonymised into Mesonacis.[1]
Olenellus[2][5][6][3]
  • Olenellus sp.
  • O. puertoblancoensis(?)
 Olenellid trilobite. Olenellus sp. previously described as Paedumias sp. which was later synonymised into Olenellus.[1]
Onchocephalus[2][5]
  • Onchocephalus sp.
 Ptychoparid trilobite.
Ptychoparioid[2][6][3]
  • Ptychoparioid sp. A
  • Ptychoparioid sp. B
  • Ptychoparioid sp. C
  • Ptychoparioid sp. D
 Ptychoparid trilobites.
Bonnia[1][2][5][3]
  • Bonnia sp.
 Dorypygid trilobite.
Crassifimbra[3]
  • Crassifimbra sp.
 Trilobite, family unknown.

Porifera (Sponges)

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Genus Species Notes Images
Archaeocyathus[4]
  • Archaeocyathus sp.
 Archaeocyathide sponge.

Flora

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Genus Species Notes Images
Girvanella[1]
  • Girvanella sp.
 Cyanobacteria structures.

See also

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References

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  1. ^ a b c d e f g h i j k l m 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.
  2. ^ a b c d e f g h i Mule Spring Limestone Formation Trilobites
  3. ^ a b c d e f Sundberg, Frederick A.; Webster, Mark (July 2022). ""Ptychoparioid" trilobites of the Harkless Formation and Mule Spring Limestone (Cambrian Series 2, Stage 4), Clayton Ridge, Nevada". Journal of Paleontology. 96 (4): 886–920. doi:10.1017/jpa.2021.124.
  4. ^ a b Pruss, Sara B.; Karbowski, Grace; Zhuravlev, Andrey Yu; Webster, Mark; Smith, Emily F. (30 June 2024). "DEAD CLADE WALKING: THE PERSISTENCE OF ARCHAEOCYATHUS IN THE AFTERMATH OF EARLY CAMBRIAN REEF EXTINCTION IN THE WESTERN UNITED STATES". Palaios. 39 (6): 210–224. doi:10.2110/palo.2024.005.
  5. ^ a b c d e 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.
  6. ^ a b Sundberg, Frederick A.; McCollum, Linda B. (September 2003). "Early and Mid Cambrian trilobites from the outer‐shelf deposits of Nevada and California, USA". Palaeontology. 46 (5): 945–986. doi:10.1111/1475-4983.00328.