[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Concretions and dinosaur bones

This is a very underinvestigated phenomenon. I've had mind to start a project 
on British Wessex Fm dinosaur bone concretions and their occurrence, since we 
get alot of bones encased in siderite, with some very interesting associations 
(and lack of associations). I have not seen this occurring as much in the North 
American beds I have worked in, and I suspect this is due to the fact that the 
majority of the material we recover here is from sandstones. Chemically or 
biochemically formed concretions seem more prevalent in mudstones, especially 
when associated with anoxia. I discussed this with someone who had a poster on 
a similar topic at GSA 2001, but I can't remember his name, nor the poster 

In the wessex, we also get bones acting as local reducing agents: bones in Fe3+ 
rich red marls are often surrounded by a halo (<1.5cm) of blue reduced 
sediment. The iron from this sediment concentrates in the bone. The same occurs 
with wood in oxidised red marls; we use this phenomenon to help find bones 
before they are actually exposed. Iron in bone is in its reduced form, Fe2+, 
and we get pyrite preserved often also. there are all sorts of interesting 
preservational quirks depending on which facies you are working in here. I just 
don't have the lab facilities to do anything properly.

There isn't huge amounts of literature, but you might want to check out some of 
the work on the fossilisation process by Derek Briggs, or Clive Trueman. 
Weigelt mentioned fatty waxes that formed from hydrolysed organic tissue 
(adipocere). There was a good poster on this subject at SVP... 2004? about a 
dead rhino that had been buried for 15 years or so, and had recently been dug 

A good old ref on this (I have the pdf if anyone wants it: 402k):

Berner (1968), calcium carbonate concentrations formed by the decomposition of 
organic matter, Science, 195-197. 


----- Original Message ----
From: Robert Simon <dino_safaris@yahoo.com>
To: dinosaur@usc.edu
Sent: Wednesday, 15 March, 2006 7:55:18 PM
Subject: Concretions and dinosaur bones

Have there been any papers published on concretions
forming around dinosaur bones? Having prepared many
dinosaur bones from the Morrison formation of Wyoming,
I have noticed patterns. A number of bones are totally
encased in hard siliceous and lime concretions. Often,
the spinal cavites of vertebrae are filled with
exceptionally hard matrix, much harder than the matrix
surrounding the overall bones. There must be chemical
reactions occurring during the fossilization process
that is creating these matrix changes. Also, many
bones are separated from the encapsulating matrix by
rinds of crystalline gypsum. Larger bones have thicker
gypsum rinds. 

Bob Simon

Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around