5.4" Ammonite (Physodoceras) Fossil on Rock - Germany

This is a beautiful ammonite fossil of the genus Physodoceras sp., collected from the Gräfenberg Quarry of Bavaria, Germany. It's upper Jurassic in age, or approximately 155 million years old. Most of the rock has been removed to expose this large ammonite. There are a variety of other smaller marine fossils scattered throughout the rock.

The Gräfenberg Quarry is famous for the green ammonites (mostly Ardescia) that are found within the sedimentary rock. The green coloration of the ammonites is caused by the mineral glauconite. When exposed to weathering or erosion, glauconite will change color to orange, brown and/or yellow.

Ammonites were predatory mollusks that resembled a squid with a shell. These cephalopods had eyes, tentacles, and spiral shells. They are more closely related to a living octopus, though the shells resemble that of a nautilus. True ammonites appeared in the fossil record about 240 million years ago. The last lineages disappeared 65 million years ago at the end of the Cretaceous.

What an ammonite would have looked like while alive.
What an ammonite would have looked like while alive.

Physodoceras sp.
Gräfenberg Quarry, Bavaria, Germany
5.4" wide ammonite on 4.6 x 4.8" rock
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