Ngoc Xuyen, locality 2 (Silurian of Vietnam)

Where: Vietnam (20.7° N, 106.8° E: paleocoordinates 11.0° N, 128.3° E)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Do Son Formation, Pridoli (423.0 - 419.2 Ma)

• The relative homogeneity of the Do Son Formation first suggested that it was entirely Givetian-Frasnian in age, as indicated by the fishes and plants, supposedly from the lower member. However, the excavations made in the eurypterid-bearing locality at Ngoc Xuyen revealed some inconsistencies in this assessment. First, the eurypterid belongs to the genus Rhinocarcinosoma, hitherto known exclusively from the Upper Silurian, yet this very rare taxon may well have gone unnoticed and survived until the Late Devonian. Second, the fish remains found in crustacean burrows just above the eurypterid-bearing clay lens do not belong to any of the taxa described from the "lower member." One of these remains ... is strikingly similar to a placoderm found in the new Upper Silurian fish locality of My Duc. Third, some claystone horizons, presumably of the middle member, yield psilophyte remains which have been referred to Cooksonia and suggested an Early Devonian age. Fourth, palynological samples (mainly triradiate spores) that are diagnostic of Late Silurian age have been obtained from locality 2 .

• group of beds-level stratigraphic resolution

Environment/lithology: marginal marine; lithified, brown sandstone

• Contains acritarchs and scolecodonts, indicating marine incursions in this part of the sequence
• Lighter brown, sandier lithology within a sequence of interbedded coarse sandstones and shales

Size classes: macrofossils, mesofossils, microfossils

Preservation: soft parts, original chitin, amber

Collected by P. Janvier, S.J. Braddy, D.N. Truong in 1987, 1993

• Repository: Institute of Geology and Mineral Resources (IGMR), Do ng Da, Hanoi, Vietnam

Primary reference: S. J. Braddy, P. A. Selden, and D. N. Truong. 2002. A new carcinosomatid eurypterid from the upper Silurian of northern Vietnam. Palaeontology 45:897-915 [M. Clapham/M. Clapham]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 184695: authorized by Matthew Clapham, entered by Matthew Clapham on 19.03.2017

Creative Commons license: CC BY (attribution)

Taxonomic list

 Xiphosurida -
Hughmilleria sp. eurypterid
 Xiphosurida - Carcinosomatidae
Rhinocarcinosoma dosonensis Braddy et al. 2002 eurypterid