Baissa (PIN collection 1668, layer 19) (Cretaceous of Russian Federation)

Where: Buryatia, Russian Federation (53.3° N, 112.1° E: paleocoordinates 56.0° N, 108.5° E)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Zaza Formation, Aptian (125.0 - 113.0 Ma)

• C. longipoda, E. trisetalis and Lycoptera all occur in the Zaza Formation indicating that this formation could be correlated with the upper Yixian Formation and the lower Jiufotang Formation in western Liaoning, which have a duration of 122.5-120 Ma. So it is possible to assign the Zaza Formation to an Aptian age. Also correlated with Barremian-Aptian based on plants and pollen.

• group of beds-level stratigraphic resolution

Environment/lithology: lacustrine - large; lithified 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: M. B. Mostovski. 1995. New taxa of Ironomyiidae (Diptera, Phoromorpha) from the Cretaceous of Siberia and Mongolia. Paleontological Journal 30:318-331 [M. Clapham/M. Clapham/M. Clapham]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 125792: authorized by Matthew Clapham, entered by Matthew Clapham on 24.03.2012, edited by Jered Karr

Creative Commons license: CC BY (attribution)

Taxonomic list

 Hemiptera - Mimarachnidae
Saltissus eskovi3 Shcherbakov 2007 planthopper
PIN 1668/2550
 Hemiptera - Notonectidae
"Clypostemma xyphiale" = Notonecta xyphiale2
"Clypostemma xyphiale" = Notonecta xyphiale2 Popov 1964 true bug
 Diptera - Ironomyiidae
Hermaeomyia bisaetigera Mostovski 1995 ironic fly
PIN 1668/1997
 Diptera - Eremochaetidae
Eremomukha (Eremocreta) sorosi1 Mostovski 1996 fly
PIN 1668/1968