Thanatocoenose

This sort of thanatocoenose is typical of lakes with a semi-arid climate (Early Triassic period in the Kuznetsk Basin, Middle Jurassic- Lower Cretaceous of Middle Asia).

The fossil diatom assemblage or thanatocoenose found in sediments typially represents as little as 1-5% of the original living assemblage or biocoenose.

Given that paleozoologists sample the geological record (i.e., where faunal remains are deposited as a particular kind of sedimentary particle), they don't always have a complete thanatocoenose lying on the lab table.