Bang Song Tho, Kanchanaburi, western Thailand (Ordovician of Thailand)

Where: Thailand (14.8° N, 98.8° E: paleocoordinates 21.6° N, 143.4° E)

• coordinate stated in text

• outcrop-level geographic resolution

When: Bo Ngam Formation (Song Tho Group), Middle Ordovician (470.0 - 458.4 Ma)

Environment/lithology: marine; lithified, gray limestone and lithified shale

• The Middle Ordovician Bo Ngam Formation is composed of dark grey, well-bedded limestones with intercalated phyllitic shales containing cephalopods and crinoids in some places.

Size classes: macrofossils, mesofossils

• The columnal fauna of this rock collection is undoubtedly richer and more diverse than can be described herein, but the crude mouldic preservation in argillaceous matrix limits the available information. Shell hashes in these rocks are rich in small columnals (Fig. 1G), amongst other fragments, but these are both too fragile and too poorly preserved to be accurately determined in such a friable substrate; similarly, they are unworthy of detailed illustration. Further, what might appear to be a columnal in such a setting may instead be a broken fragment of a decalcified tube of an annelid or a mollusc. Larger columnals are identifiable (Figs 1C, E, F, HK, L, 2D, E), but rarely have an identifiable counterpart.

Preservation: mold/impression

Collected by A. J. Boucot and W. Tansathien in 1997, 2004

Primary reference: C. R. C. Paul, A. J. Boucot, S. K. Donovan, R. Zhan, and W. Tansathien. 2019. Primitive stalked echinoderms from the Middle Ordovician (Darriwilian) of Bang Song Tho, Kanchanaburi, western Thailand. Geological Magazine 156(1):147-171 [S. Cole/S. Cole/P. Wagner]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 191371: authorized by Selina Cole, entered by Selina Cole on 24.01.2018

Creative Commons license: CC BY (attribution)

Taxonomic list

Rhombifera
 Glyptocystitoida - Cheirocrinidae
Cheirocystella sp. Paul 1972
Cheirocrinus indet. Eichwald 1856
 Rhombifera - Caryocrinitidae
Paracaryocrinites indet. Chen and Yao 1993
Diploporita
 Aristocystitoida - Aristocystitidae