Re: Preservation bias

[dis@gj.net]

Sam Girouard wrote:
> 
> All,
> 
> >Are there any instances of both plant and animal fossils being found at
> >the same time? Can they occur in the same strata and circumstances?
> 
>         Yeah, lots of times. It is very common to find fossil foliage
> jumbled up around fossil bone. I got a pile of references on this, If I
> could dig 'em up. 

HOWEVER....

        Preservational bias is very common. Plants do not preserve well 
in alkaline sediments so our records of plants and pollen in 
environments with less than 20 inches of rain a year is very poor.
        Acid is bad for bones. Thus bones are rarely found in sediments 
closely associated with coal. Bone is more tolerant than shell to many 
organic acids however. I have seen bone from a coal seam. One hadrosaur 
leg bone had no mineral portion left. It was incrushed and so light that 
when it was handed to me, I almost through it up into the air.
        Because of this microenvironments with the right chemistry are 
very important to fill out the biota.

Jim K.