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Baissa (PIN collection 1668, layer 25) (Cretaceous of Russian Federation)

Where: Buryatia, Russian Federation (53.3° N, 112.1° E: paleocoordinates 57.1° N, 110.8° E)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Zaza Formation, Berriasian (145.5 - 140.2 Ma)

• group of beds-level stratigraphic resolution

Environment/lithology: lacustrine - large; lithified, carbonaceous siltstone and lithified marl

• "The water body is reconstructed as an intermontane lake with the depth of 20 - 30 meters (LYAMINA 1980) situated within a granite massif. The presence of thick layers of the bituminous shales shows that the lake was meromictic, with the oxygen deficiency and high hydrogen sulphur level in the hypolimnion. However, the oxygenated epilimnion should be thick, with a lower boundary well beneath the limit of episodic wave action because no suffocation events are documented. The abundance of caddisflies, dobsonfly larvae and other groups intolerant to oxygen deficiency shows that in more shallow areas the water was clear and well-oxygenated even near the bottom. The lake ecosystem was highly productive as indicated by its complex trophic structure (Fig. 2) with several levels of predators up to the large sturgeon-like fish Stychopterus as well as by the extremely high abundance of planetonivorous phantom midges (SINICHENKOVA & ZHERIKHIN 1996)." ZHERIKHIN et al., 1999

Size class: macrofossils

Preservation: mold/impression

Collected by PIN institute in 1959; reposited in the PIN

Primary reference: V. N. Vishnyakova. 1976. Relict Archipsyllidae (Insecta, Psocoptera) in the Mesozoic fauna. Paleontological Journal 10:180-188 [M. Clapham/M. Clapham] more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 124523: authorized by Matthew Clapham, entered by Matthew Clapham on 17.02.2012, edited by Jered Karr

Creative Commons license: CC BY-NC-ND (attribution-noncommercial-no derivatives)