I keep reading that the cause of certain fossil graveyards are due to anoxic conditions of some body of water, whereby the lack of oxygen means reduced scavengers and bacteria that would contribute to decomposition, and thus greater preservation of fossils.  This seems to make sense, but I'm having trouble finding the empirical studies that demonstrate this effect.

Are there documented decomposition tests where a caracass (or perhaps varying types/sizes of caracasses) remained well preserved in a natural anoxic body of water for months/years to confirm this? 

Also, aren't there still types of scavengers and/or bacteria that live in waters with very low levels of oxygen?   Would something as delicate as a the wings of a fly really bypass decomposition in water, anoxic or not?

Hi Bill,

I don’t know about any studies that you’ve asked for however I can try to answer the part about insect wings.

You’re right to be skeptical as wings are fragile and likely to become broken during the fossilization process. However, there are a couple of methods by which this can happen, the most common one being preservation in amber (which is relatively non-destructive and even the animal’s parasites are sometimes well preserved in this condition).

There is also another process called premineralization in which the insect is preserved inside a mineralized nodule, where a nodule grows around the insect preserving it in 3D and protecting it from any outside influences examples include those from the Santana Formation in Brazil. It also helps if the original soft tissue is re-mineralized quickly.

Last edited by Kyle Freeman (18th Sep 2013 20:59:28)