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Re: Exact length of Sue



Dan

Thanks! Schopf’s paper is behind a paywall, unfortunately,: 
http://www.sciencedirect.com/science/article/pii/0034666775900056

All best,

Jerry

On Apr 21, 2015, at 9:56 PM, Dan Chure <danchure@easilink.com> wrote:

> Back in the late 1970s USGS personnel did a chemical analysis of dinosaur 
> bone samples from the Carnegie quarry face and they were about 85% identical 
> BY VOLUME (not weight) with the composition of bone when the animal was 
> alive. That seems to be about standard fare, maybe even less depending on the 
> post mortem history of the bone.  Schopf did a paper in the late? 1970s 
> entitled "Modes of fossilization" in Paleo3 (as I recall) which was an 
> excellent review of the subject. Maybe there have been better ones since 
> then. Sorry I can't provide a better citation at the moment but I don't have 
> it at hand.  I know I don't have a pdf.
> 
> Dan
> 
> On 4/21/2015 7:24 PM, tholtz wrote:
>> That is rather out-of-date thinking, actually. Most fossil bone is 
>> permineralized: the original bony mineral (hydroxylapatite) and even 
>> collagen is still present, but the pore space is filled to some degree with 
>> minerals from ground water. Some fossil bone is unaltered: nothing added, 
>> nothing lost except the greasy organics. Actual honest-to-goodness 
>> replacement is very rare for fossil bone, although more common in fossils of 
>> some other groups.
>> 
>> So the real bone is there. But there is other stuff added.
>> 
>> On 2015-04-21 21:13, Victoria & Jerrold Alpern wrote:
>>> Dan,
>>> 
>>> What I meant was that the organic bones that supported the dinosaur in
>>> life were replaced underground by minerals that formed an exact cast
>>> of the originals. These are precise enough replicas that they carry
>>> the information, including isotope signatures, LAGs, etc. that provide
>>> the raw material of paleohistology. If I am wrong, or have stated the
>>> process incorrectly, please tell me. Many who come to AMNH are
>>> interested in dinosaurs but have never considered the process of
>>> fossilization.  My only wish is to convey accurate information to AMNH
>>> visitors.
>>> 
>>> Thank you!
>>> 
>>> Jerry Alpern
>>> 
>>> On Apr 21, 2015, at 8:51 PM, Dan Chure <danchure@easilink.com> wrote:
>>> 
>>>> I don't think this is quite true: "most fossils are themselves casts of 
>>>> the original bones." If it was, there would be no discipline of 
>>>> paleohistology.
>>>> 
>>>> Dan
>>>> 
>>>> 
>>>> On 4/21/2015 10:37 AM, Victoria & Jerrold Alpern wrote:
>>>>> Thanks! I had thought both legs of AMNH 5027 were replicas of CM 9380, 
>>>>> which I assume is the holotype we sold to the Carnegie in the 1940s. Now 
>>>>> I’m going to have to revise what I tell visitors!  They often assume that 
>>>>> what they see are “fakes”, by which they mean copies. They are happy to 
>>>>> learn that most of our 4th Floor fossils are genuine, although I always 
>>>>> add that most fossils are themselves casts of the original bones.
>>>>> 
>>>>> Jerry Alpern
>> 
> 
>