Sikhiri River: Katian, Bolivia

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Protozoa
/Desmochitina minor cocca
Rhynchonellata - Orthida - Draboviidae
Strophomenata - Strophomenida - Rafinesquinidae
unclassified
see common names

Geography
Country:Bolivia
Coordinates: 17.2° South, 66.3° West (view map)
Paleocoordinates:47.4° South, 173.2° East (Wright 2013)
Basis of coordinate:estimated from map
Altitude:3900 meters
Geographic resolution:outcrop
Time
Period: Ordovician Epoch: Late Ordovician
Stage: Katian 10 m.y. bin: Ordovician 5
Key time interval: Katian
Age range of interval: 452.8 - 445.2 m.y. ago
Stratigraphy
Formation:San Benito
Local section:Sikhiri River Local bed:15-26 m
Local order:bottom to top
Stratigraphic resolution:group
Stratigraphy comments: The age of the San Benito Formation has been considered largely as Late Ordovician on the basis of its stratigraphic position below the Hirnantian/ Early Silurian Cancañiri Formation and above the Anzaldo Formation, which is significant because it yielded numerous articulated specimens of the pteraspidomorph agnathan Sacabambaspis janvieri Gagnier, Blieck and Rodrigo, 1986. Although the precise age of the Anzaldo Formation remains unclear, a late Darriwillian to early Sandbian age is accepted on the basis of its palynomorph content (Gagnier et al., 1986; Suárez Soruco, 2000; Davies et al., 2007) as well as its correlation with conodont-dated stratigraphic units of Argentina bearing microremains of Sacabambaspis (Albanesi et al., 1995; Albanesi and Astini, 2002). Unpublished palynomorphs and chitinozoans from the beds yielding the brachiopods described in this paper include Villosacapsula setosapellicula (Loeblich), Rhabdochitina cf. magna Eisenack, Ancyrochitina cf. ancyrea Eisenack and Desmochitina minor cocca Eisenack suggesting a Katian age (Pérez-Leyton, 1996).

Overall consensus: this is basal Katian.
Lithology and environment
Primary lithology: sandstone
Secondary lithology:micaceous siltstone
Includes fossils?Y
Lithology description: The San Benito Formation is a c. 500 m thick succession of shallow-water quartzitic sandstones with minor interbeds of dark gray micaceous siltstones. Shelly fossils have been found at few horizons and consist mainly of linguliformean brachiopods, bivalves(Suárez Soruco, 1976; Sánchez and Suárez Soruco, 1996), and a few homalonotid trilobite remains. Poorly preserved graptolites occur occasionally in the shaly beds.
Environment:shoreface
Taphonomy
Modes of preservation:cast
Size of fossils:macrofossils
Collection methods and comments
Reason for describing collection:taxonomic analysis
Metadata
Database number:167263
Authorizer:P. Wagner Enterer:P. Wagner
Research group:marine invertebrate
Created:2015-03-09 20:50:09 Last modified:2025-02-22 15:12:02
Access level:the public Released:2015-03-09 20:50:09
Creative Commons license:CC0
Reference information

Primary reference:
54570. J. L. Benedetto. 2013. Upper Ordovician Brachiopods from the San Benito Formation, Cordillera del Tunari, Bolivia. Ameghiniana 50(4):418-428 [P. Wagner/P. Wagner]