Sella Formation Explained

Sella Formation
Type:	Geological formation
Period:	Dapingian
Age:	Dapingian-Darriwilian ~
Prilithology:	Siltstone, sandstone
Otherlithology:	Shale, limestone, coquina
Region:	Tarija Department
Country:	Bolivia
Coordinates:	-21.4°N -64.6°W
Paleocoordinates:	-42.8°N -131.6°W

The Sella Formation is a Dapingian to Darriwilian geologic formation of southern Bolivia. The grey to green bioturbated siltstones interbedded with thin sandstone layers bear lenticular shell beds. Other parts of the formation contain yellow-green limy shales and grey sandy limestones. Coquinas often fill gutter casts and included brachiopods, trilobites, bivalves and nautiloids. The sediments were deposited in an open marine environment.^{[1] [2] [3] [4] [5]} The species Coxiconchia sellaensis was named after the formation.

Fossil content

The formation has provided the following fossils:

• Baltograptus minutus^[6]
• Coxiconchia sellaensis
• Desmorthis segnis
• Glyptorthis imbrex
• Hemiprionodonta lusitanica
• Lingulocystis boliviensis
• Natasia boliviensis
• Pliomeridius sulcatus
• Redonia riojana
• Ribeiria spinosa
• Peelerophon cf. oehlerti
• Ampyx sp.
• Boeckaspis sp.
• Branisaspis sp.
• Bucania sp.
• Colpocoryphe sp.
• Cosmogoniophorina sp.
• Ctenodonta sp.
• Cyptendoceras sp.
• Didymograptus sp.
• Endoceras sp.
• Eothinoceras sp.
• Famatinolithus sp.
• Haploprimitia sp.
• Hoekaspis sp.
• Lecanospira sp.
• Lonchodomas sp.
• Maclurites sp.
• Quadrilobella sp.
• Parapyxion sp.
• Protocycloceras sp.
• Sibiritella sp.
• Suriaspis sp.
• Synhomalonotus sp.
• Technophorus sp.
• Trinucleus sp.

See also

• List of fossiliferous stratigraphic units in Bolivia

References

Bibliography

Further reading

• C. Babin and L. Branisa. 1987. Ribeiria, Peelrophon y otros molluscos del Ordovícico de Bolivia. 4˚ Congreso Latinoamericano de Paleontología 1:119-129
• L. Branisa. 1965. Los fosiles guias de Bolivia: I. Paleozoico. Boletin de Servicio Geologico de Bolivia. La Paz, Bolivia 6:1-282
• V. Havlicek and L. Branisa. 1980. Ordovician brachiopods of Bolivia: Succession of assemblages, climate control, affinity to Anglo-French and Bohemian provinces. Rozpravy Ceskoslovenske Akademie Ved. Rada Matematickych a Prirodnich Ved. Academia Praha, Prague, Czechoslovakia 90(1):1-54
• T. M. Sánchez and C. Babin. 2005. Lower Ordovician bivalves from southern Bolivia: paleobiogeographic affinities. Ameghiniana 42(3):559-566
• R. Suárez Soruco. 1976. El sistema ordovícico en Bolivia. Revista Tecnica YPF Bolivia 5(2):111-123

Notes and References

1. https://paleobiodb.org/classic/displayCollResults?collection_no=167377 Sella C
2. https://paleobiodb.org/classic/displayCollResults?collection_no=9104 Pantipampa, 3 kilometers east of Belle Vista
3. https://paleobiodb.org/classic/displayCollResults?collection_no=57172 Sella, Bed 1
4. https://paleobiodb.org/classic/displayCollResults?collection_no=9107 Sella
5. https://paleobiodb.org/classic/displayCollResults?collection_no=57173 Sella Bed 4
6. Suárez Riglos et al., 2018, p.64