According to the American Geological Institute's Glossary of Geology, 4th edition, the definition of thanatocoenosis is the following:
"thanatocoenosis (n): a) a set of fossils brought together after death by sedimentary processes, rather than by virtue of having originally lived there collectively; b)...all the fossils present at a particular place in a sediment" [note: I trimmed some of the definition a bit]
The word comes from the Greek thanatos ("death") and koinos ("general" or "common").
Thanatocoenosis shares a root with thanatology (the study of death), thanatophobia (the fear of death), and thanatopsis (a view or thought about death).
This was also another word I considered as a title for this blog, but rejected because it's hard to spell...
7 years ago