Zone 1 [Barail Gp] (Oligocene of India)

Where: India (23.0° N, 93.0° E: paleocoordinates 14.9° N, 95.2° E)

• coordinate stated in text

• local area-level geographic resolution

When: Barail Group, Early/Lower Oligocene (33.9 - 28.4 Ma)

• STRATIGRAPHIC RELATIONS: From the Barail Group (Oligocene), for which a lower contact is not observed, and is overlain by sediments of the Lower Bhuban Group (Late Oligocene-Early Miocene). THICKNESS: From bed of 11.5 m in thickness within 40-50 m thick section. AGE: Late Eocene-Oligocene. Fossils are from above Eocene portion, and given that the overlying unit also contains Oligocene-age facies, it is here assigned to a Early Oligocene age. STRATIGRAPHIC POSITION: From near top of section.

• bed-level stratigraphic resolution

Environment/lithology: offshore; lithified, silty sandstone

• ENVIRONMENT: Shallow marine, siliciclastic environment.
• SPECIFIC LITHOLOGY: Grey silty sandstone. LITHIFICATION: Lithified, on the basis of figured specimens (casts and molds).

Size class: macrofossils

Preservation: cast, mold/impression

Collected by Tiwari; reposited in the GSI

Collection methods: surface (in situ),

• COLLECTORS: R. P. Tiwari (unknown date). REPOSITORY: Geological Survey of India (GSI), Pachhunga University College (PUC)

Primary reference: R. P. Tiwari and R. P. Kachhara. 2003. Molluscan biostratigraphy of the Tertiary sediments of Mizoram, India. Journal of the Paleontological Society of India 48:65-88 [A. Hendy/A. Hendy]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 78616: authorized by Austin Hendy, entered by Austin Hendy on 11.02.2008

Creative Commons license: CC BY (attribution)

Taxonomic list

• COVERAGE: Exhaustive for gastropoda and bivalvia. NOMENCLATURE: Not an authoritative publication, but with fairly modern nomenclature, subgenus and species resolution assignments
Bivalvia
 Nuculanida - Yoldiidae
Yoldia sp. Möller 1842 clam
 Ostreida - Ostreidae
Ostrea sp. Linnaeus 1758 oyster
 Pectinida - Pectinoidae
Chlamys sp. Röding 1798 scallop
 Cardiida - Cardiidae
Cardium sp. Linnaeus 1758 cockle
 Cardiida - Tellinidae
Tellina sp. Linnaeus 1758 tellin clam
 Cardiida - Veneridae
Venus pasokensis venus clam
Sunetta yethana venus clam
Meretrix agrestis venus clam
Gastropoda
 Sorbeoconcha - Ficidae
Ficus sp. Röding 1798 fig shell
Ficus conditus Brongniart 1823 fig shell
Echinoidea
 Cidaroida - Cidaridae
Cidaris sp. Leske 1778 pencil urchin