USNM 16000d, Tinu Formation, Oaxaca, Mexico - Robison and Pantoja-Alor 1968: Tremadoc, Mexico
List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
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Agnostida
- Agnostidae
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? Gymnagnostus mexicanus n. sp.
Robison and Pantoja-Alor 1968
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Trilobita
- Asaphida
- Dikelocephalidae
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Saukia globosa n. sp.
Robison and Pantoja-Alor 1968
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1 specimen | |||||||||
| 1 pygidium | ||||||||||
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Trilobita
- Olenida
- Olenidae
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Plicatolinella ocula n. sp.
Robison and Pantoja-Alor 1968
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Triarthrus tetragonalis
(Harrington 1938)
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10 specimens | |||||||||
| recombined as Bienvillia tetragonalis | ||||||||||
| 10 cranidia [originally entered as Triarthus tetragonalis] | ||||||||||
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Parabolinella argentinensis
Kobayashi 1936
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9 specimens | |||||||||
| 5 cranidia, 2 librigenae, 2 pygidia | ||||||||||
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Leptoplastides marianus
(Hoek 1912)
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| see common names | ||||||||||
Geography
| Country: | Mexico | State/province: | Oaxaca |
| Coordinates: | 17.4° North, 97.2° West (view map) | ||
| Paleocoordinates: | 16.2° South, 105.0° West | ||
| Geographic resolution: | outcrop |
Time
| 10 m.y. bin: | Cambrian-Ordovician | ||
| *Period: | Early/Lower Ordovician - Middle Ordovician | *Epoch: | Tremadoc |
| Key time interval: | Tremadoc | Zone: | Saukia |
| Age range of interval: | 485.00000 - 477.70000 m.y. ago | ||
| * legacy (obsolete) database fields | |||
Stratigraphy
Lithology and environment
| Primary lithology: | lithified siltstone |
| Lithology description: General for fossiliferous portion of member: Interbedded thin to medium bedded dark fossiliferous (bioclastic/skeletal) limestone and thin to medium beds of light, generally unfossiliferous shale. Specific for this collection: siltstone | |
Taphonomy
Collection methods and comments
| Collection excludes: | some macrofossils |
| Collection methods: | field collection |
| Reason for describing collection: | taxonomic analysis |
| Collection method comments: The fauna correlate (approximately) with the North American Saukia Zone (Late Cambrian), and with the lower Tremadoc of Europe and South America. However, probably less than 20% of the trilobite genera from the Tinu Formation have been reported from rocks either younger or older than the Tremadoc. On an end note, Robison talks of the differing opinions on the relative age placement of the Saukia Zone fauna. Conclusions are that the European Saukia Zone and those found in Mexico have an age of Early Ordovician and not Late Cambrian as determied for the ""North American Saukia Zone"". | |
| Taxonomic list comments:The taxonomic list only includes trilobites and fauna important for future biostratigraphy: cephalopods (16000_), conodonts (16000_,16001_,16002_), gastropods (16001_, 16002_). The section of study also includes echinoderms, sponges, ostracodes, and problematica, but there placement in the individual collections is not documented. | |
Metadata
| Database number: | 9826 | ||
| Authorizer: | M. Patzkowsky | Enterer: | P. Borkow | Research group: | marine invertebrate |
| Created: | 2001-01-24 09:56:51 | Last modified: | 2003-07-18 18:01:39 |
| Access level: | the public | Released: | 2001-01-24 12:01:00 |
| Creative Commons license: | CC BY |
Reference information
Primary reference:
| 853. | R. A. Robison and J. Pantoja-Alor. 1968. Tremadocian trilobites from the Nochixtlan Region, Oaxaca, Mexico. Journal of Paleontology 42(3):767-800 [M. Patzkowsky/P. Borkow] |