From Newsgroup: talk.origins

https://www.science.org/content/article/scientists-directly-date-dino-eggshells-first-time

https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2025.1638838/full

I don't know how well this method can work. Calcium crystals are formed
in an egg shell, but Uranium is known to replace bone minerals during fossilization. The Dino paleontologist that found a bunch of Utah dinos
used to look for fossils using a geiger counter. The fossils were more radioactive than the surrounding matrix. They claim to have dated the biogenic crystals in the dino egg shell, but the egg was also filled
with calcite crystals that they claimed did not give consistent results.
They noted that the calcite crystals were less permiable than the egg shells, so they are relying on uranium accumulation after burial.

This does not seem to be a reliable dating method.

Ron Okimoto

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From Newsgroup: talk.origins

On 14/09/2025 14:05, RonO wrote:

https://www.science.org/content/article/scientists-directly-date-dino- eggshells-first-time

https://www.frontiersin.org/journals/earth-science/articles/10.3389/ feart.2025.1638838/full

I don't know how well this method can work.-a Calcium crystals are formed
in an egg shell, but Uranium is known to replace bone minerals during fossilization.-a The Dino paleontologist that found a bunch of Utah dinos used to look for fossils using a geiger counter.-a The fossils were more radioactive than the surrounding matrix.-a They claim to have dated the biogenic crystals in the dino egg shell, but the egg was also filled
with calcite crystals that they claimed did not give consistent results.
-aThey noted that the calcite crystals were less permiable than the egg shells, so they are relying on uranium accumulation after burial.

This does not seem to be a reliable dating method.

Ron Okimoto

The process appears to be

1) Calcite, from carbonate-bearing fluids, is deposited within the eggs.
The calcite contains traces of uranium.
2) This uranium decays over time to radiogenic lead.
3) Assuming that the system has been closed since deposition the age of
the calcite can be measured by U-Pb dating.

In principle isochron dating could be used to test the assumption of
closure, but it seems likely that all samples have a common composition
and history which strikes me as making isochron dating unworkable.
--
alias Ernest Major

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From Newsgroup: talk.origins

On 9/14/2025 10:52 AM, Ernest Major wrote:

On 14/09/2025 14:05, RonO wrote:

https://www.science.org/content/article/scientists-directly-date-dino-
eggshells-first-time

https://www.frontiersin.org/journals/earth-science/articles/10.3389/
feart.2025.1638838/full

I don't know how well this method can work.-a Calcium crystals are
formed in an egg shell, but Uranium is known to replace bone minerals
during fossilization.-a The Dino paleontologist that found a bunch of
Utah dinos used to look for fossils using a geiger counter.-a The
fossils were more radioactive than the surrounding matrix.-a They claim
to have dated the biogenic crystals in the dino egg shell, but the egg
was also filled with calcite crystals that they claimed did not give
consistent results. -a-aThey noted that the calcite crystals were less
permiable than the egg shells, so they are relying on uranium
accumulation after burial.

This does not seem to be a reliable dating method.

Ron Okimoto

The process appears to be

1) Calcite, from carbonate-bearing fluids, is deposited within the eggs.
The calcite contains traces of uranium.
2) This uranium decays over time to radiogenic lead.
3) Assuming that the system has been closed since deposition the age of
the calcite can be measured by U-Pb dating.

In principle isochron dating could be used to test the assumption of closure, but it seems likely that all samples have a common composition
and history which strikes me as making isochron dating unworkable.

It was the probably contaminated egg shell calcium that gave them the
date. The calcite that formed within the egg gave them different
results. They claimed that the calcite crystals that formed inside of
the egg were less permiable to infiltration, so they knew that they had
to consider uranium coming in and contaminating the egg shell calcite.
The calcite inside of the egg would contain the uranium that was in
solution when those crystals were forming after the egg had been buried.
Dino bones are known to concentrate uranium. It seems to replace bone minerals. If the lead isotope does not accumulate in fossils they would expect to get a younger more recent date than when the egg had actually
been produced. They need to find out the possible uranium content of a
birds like emu or ostrich and see if there is too much uranium and decay product in their samples.

Ron Okimoto

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