Re: [dinosaur] I can't see the skull

[Ben Creisler <bcreisler@gmail.com>]

Ben Creisler

bcreisler@gmail.com

In the case of the Corral Bluffs mammal skulls, it's a freshwater river and floodplain environmentÂwith mudstone and sandstone. The Science paper says:

Most are three-dimensionally preserved in hydroxyapatite concretions and are found in all observed facies, often as articulated skeletons or skulls with intact delicate structures such as middle ear and hyoid elements.

===

This free paper from last year fills in details about marine concretions around organic remains. It's marine, but I assume something similar happened.

Hidekazu Yoshida, Koshi Yamamoto, Masayo Minami, Nagayoshi Katsuta, Sirono Sin-ichi & Richard Metcalfe (2018)
Generalized conditions of spherical carbonate concretion formation around decaying organic matter in early diagenesis.
Scientific Reports 8, Article number: 6308 (2018)
doi:10.1038/s41598-018-24205-5
https://www.nature.com/articles/s41598-018-24205-5

Virus-free. www.avg.com

On Tue, Oct 29, 2019 at 3:06 PM David Marjanovic <david.marjanovic@gmx.at> wrote:

> What process causes the concretion?

Precipitation of minerals from groundwater in the acidic-or-whatever microenvironment created by the decay of soft tissue. (Remember that most fossils are fossils of rotting cadavers.) Or maybe just crystal growth on the skull itself.