Trilobite zone

Trilobites are used as index fossils to subdivide the Cambrian period. Assemblages of trilobites define trilobite zones.[1] The Olenellus-zone has traditionally marked the top of the Lower Cambrian,[2] and is followed by the Eokochaspis zone.[3]

The last two zones of the Middle Cambrian are the BathyuriscusElrathina-zone (contemporaneous with the Burgess Shale) and the subsequent Bolaspidella-zone (starting at the base of the Drumian stage[4]). These are overlain by the lowermost Upper Cambrian Cedaria-zone.[5]

Alternative zoning names place the Burgess Shale in the Peronopsis bonnerensis-zone, which is underlain by the Oryctocephalus indicus-zone (e.g. Spence Shale) and overlain (perhaps not directly) by the Ptychagnostus punctuosus-zone.[6]

The lower Middle Cambrian[7] Glossopleura-zone (Spence Shale) is above the Albertella-zone.[8]

The Elvinia-zone is upper Cambrian.[9]

Series Stage Trilobite zone Trilobite GSSP
Furongian Stage 10 Saukia-zone (upper part), Eurekia apopsis-zone, Tangshanaspis-Zone, Parakoldinioidia-zone, Symphysurina-zone[10] Lotagnostus americanus (undecided)
Jiangshanian Ellipsocephaloides-zone, Saukia-zone (lower part) [10] Agnostotes orientalis
Paibian ? (?) Glyptagnostus reticulatus
Miaolingian Guzhangian Bolaspidella ( / Ptychagnostus praecurrens ?? ).[6] Lejopyge laevigata
Drumian Ptychagnostus atavus
Wuliuan BathyuriscusElrathina (?) Oryctocephalus indicus
Series 2 Stage 4 Olenellus Olenellus or Redlichia (undecided)
Stage 3
Fallotaspis, Nevadella First appearance of trilobites (undecided)
Terreneuvian (Pre-Trilobitic Cambrian) Stage 2 ?
  1. ^ Palmer, A.R. (1998). "A proposed nomenclature for stages and series for the Cambrian of Laurentia". Canadian Journal of Earth Sciences. 35 (4): 323–328. Bibcode:1998CaJES..35..323P. doi:10.1139/cjes-35-4-323. ISSN 1480-3313.
  2. ^ Sundberg, F. A. (2005). "The Topazan Stage, a New Laurentian Stage (Lincolnian Series_ "Middle" Cambrian)". Journal of Paleontology. Paleontological Society. 79 (1): 63–71. doi:10.1666/0022-3360(2005)079<0063:TTSANL>2.0.CO;2. JSTOR 4094961. S2CID 130681546.
  3. ^ Sundberg, F. A.; McCollum, L. B. (2000). "Ptychopariid Trilobites of the Lower-Middle Cambrian Boundary Interval, Pioche Shale, Southeastern Nevada". Journal of Paleontology. Paleontological Society. 74 (4): 604–630. doi:10.1666/0022-3360(2000)074<0604:PTOTLM>2.0.CO;2. JSTOR 1306942. S2CID 130102939.
  4. ^[bare URL PDF]
  5. ^ Robison, R. A. (1964). "Upper Middle Cambrian Stratigraphy of Western Utah". Geological Society of America Bulletin. 75 (10): 995–1010. Bibcode:1964GSAB...75..995R. doi:10.1130/0016-7606(1964)75[995:UMCSOW]2.0.CO;2. ISSN 0016-7606.
  6. ^ a b This is just younger than the Bathyuriscus-Elrathina zone, or at least just younger than the Stephen Formation. See
  7. ^ Robison, R. A.; Wiley, E. O. (1995). "A New Arthropod, Meristosoma: More Fallout from the Cambrian Explosion". Journal of Paleontology. 69 (3): 447–459. Bibcode:1995JPal...69..447R. doi:10.1017/s0022336000034855. JSTOR 1306320. S2CID 133177339.
  8. ^ Stoyanow, A. (1958). "Sonoraspis and Albertella in the Inyo Mountains, California". Geological Society of America Bulletin. 69 (3): 347–352. Bibcode:1958GSAB...69..347S. doi:10.1130/0016-7606(1958)69[347:SAAITI]2.0.CO;2. ISSN 0016-7606.
  9. ^ Stitt, J. H.; Rucker, J. D.; Diane Boyer, N.; Hart, W. D. (1994). "New Elvinia Zone (Upper Cambrian) Trilobites from New Localities in the Collier Shale, Ouachita Mountains, Arkansas". Journal of Paleontology. 68 (3): 518–523. Bibcode:1994JPal...68..518S. doi:10.1017/s0022336000025890. JSTOR 1306200. S2CID 133418468.
  10. ^ a b Landing, E.; Westrop, S.R.; Adrain, J.M. (19 September 2011). "The Lawsonian Stage - the Eoconodontus notchpeakensis FAD and HERB carbon isotope excursion define a globally correlatable terminal Cambrian stage". Bulletin of Geosciences: 621–640. doi:10.3140/bull.geosci.1251.

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