Where: Nei Mongol, China (42.1° N, 116.6° E: paleocoordinates 43.2° N, 118.6° E)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Yixian Formation, Late/Upper Valanginian (140.2 - 136.4 Ma)

• The precise age of Sandaogou in Duolun County has been unknown for a long time. This area, as a member of the Yixian Formation, consists of two rock members: the lower one (K1y1) is a set of acidic volcanic-sedimentary rock strata, and the upper one (K1y2) is a set of trachytic volcanic rock strata. In 2019, LA-ICP-MA zircon U-Pb ages of 132.2 ± 0.6 Ma and 132.8 ± 0.8 Ma were obtained in the rhyolite of the K1y1 rock member by Xue et al. Considering that the sedimentary rocks in this area exist in K1y1, we tentatively treat 132 Ma as the age of the fossil material in this study.

•The base of the Hauterivian was calculated at as 131.29 Ma by Mutterlose et al. (2021), placing this locality in the latest Valanginian.

• group of beds-level stratigraphic resolution

Environment/lithology: lacustrine - large; lithified, tuffaceous mudstone

Size classes: macrofossils, mesofossils

Preservation: adpression

Collection methods: Repository: Capital Normal University, Beijing

Primary reference: L. Y. Dai, A. P. Rasnitsyn, C. K. Shih, M. Wang, and D. Ren. 2022. New fossil Xyelidae (Insecta, Hymenoptera) from the Lower Cretaceous Yixian Formation of northeast China. Cretaceous Research 137(105249) [M. Clapham/M. Clapham]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 226075: authorized by Matthew Clapham, entered by Matthew Clapham on 15.06.2022

Creative Commons license: CC BY (attribution)