Scaphiocoelia Zone trilobites, Lower Belen Fmn., Belen-La Paz-Sicasica region (Devonian of Bolivia)

Where: La Paz, Bolivia (17.0° S, 68.0° W: paleocoordinates 63.9° S, 86.9° W)

• coordinate based on nearby landmark

• local area-level geographic resolution

When: Lower Belen Member (Belen Formation), Emsian (407.6 - 393.3 Ma)

• Scaphiocoelia Zone well recognized. Emsian age follows Isaacson (ref. 9680).

• member-level stratigraphic resolution

Environment/lithology: marine; micaceous, gray siltstone and micaceous, gray mudstone

• Isaacson (ref. 9681) interprets Scaph.-zone units as BA 2 in intracratonic basin, and succeeding units as deeper.
• From Isaacson (ref. 9681): "The lower quarter of [Lower Belen] is siltstone. Fresh surfaces gray to greenish, weathered surfaces brown...siltstone very micaceous...half-way through the unit are symmetrical ripple marks...The next half of the Lower Belen is a [gray] mudstone [micaceous]. Upper quarter of Lower Belen at Belen is a seq. of variable lithology. Predominating is siltstone, with fine-grained sandstone and mudstone appearing in interbeds...gray...[micaceous]"

Primary reference: N. Eldredge and L. Branisa. 1980. Calmoniid trilobites of the Lower Devonian Scaphiocoelia Zone of Bolivia, with remarks on related species. Bulletin of the American Museum of Natural History 165(2):181-289 [M. Foote/M. Foote/M. Foote]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 36133: authorized by Michael Foote, entered by Michael Foote on 14.01.2004

Creative Commons license: CC BY (attribution)

Taxonomic list

• Emphasis is on calmoniids, which make up the majority of Scaphiocoelia Zone trilobites, but other forms are treated as well.
 Phacopida - Calmoniidae
Kozlowskiaspis (Romanops) borealis n. subgen. n. sp. trilobite
Bainella (Belenops) insolita n. subgen. trilobite
Deltacephalaspis (Deltacephalaspis) magister n. gen. n. subgen. n. sp. trilobite
Deltacephalaspis (Prestalia) "sp. A" n. gen. n. subgen. Eldredge and Ormiston 1979 trilobite
Tarijactinoides tikaensis n. sp. trilobite
 Phacopida - Homalonotidae
"Burmeisteria" sp. Salter 1865 trilobite
"Burmeisteria s.l."