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 Bathyuriscus–Elrathina 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 Peronopsis bonnerensis 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 |
| Furongian (Upper Cambrian) |
Stage 10 |
| Stage 9 |
| Paibian |
? (?) |
| Cedaria |
| Series 3 (Middle Cambrian) |
Guzhangian |
Bolaspidella ( / Ptychagnostus praecurrens ?? ).[6] |
| Drumian |
| Stage 5 |
Bathyuriscus–Elrathina (?) |
| Eokochaspis |
| Series 2 |
Stage 4 |
Olenellus |
| Stage 3 |
| Nevadella |
| Series 1 |
Stage 2 |
? |
| Stage 1 |
References
- ^ . 35. p. 323. ISSN 1480-3313. http://article.pubs.nrc-cnrc.gc.ca/ppv/RPViewDoc?issn=1480-3313&volume=35&issue=4&startPage=323.
- ^ 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. edit
- ^ 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. edit
- ^ https://engineering.purdue.edu/Stratigraphy/references/Drumian0.pdf
- ^ Robison, R. A. (1964). "Upper Middle Cambrian Stratigraphy of Western Utah". Geological Society of America Bulletin 75: 995–992. doi:10.1130/0016-7606(1964)75[995:UMCSOW]2.0.CO;2. ISSN 0016-7606. edit
- ^ a b This is just younger than the Bathyuriscus-Elrathina zone, or at least just younger than the Stephen Formation. See
- ^ Robison, R. A.; Wiley, E. O. (1995). "A New Arthropod, Meristosoma: More Fallout from the Cambrian Explosion". Journal of Paleontology 69 (3): 447–459. JSTOR 1306320. edit
- ^ Stoyanow, A. (1958). "Sonoraspis and Albertella in the Inyo Mountains, California". Geological Society of America Bulletin 69 (3): 347–342. doi:10.1130/0016-7606(1958)69[347:SAAITI]2.0.CO;2. ISSN 0016-7606. edit
- ^ 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. JSTOR 1306200. edit
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