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Re: Exact length of Sue



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That is rather out-of-date thinking, actually.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