1.9" Carboniferous Ammonite (Muensteroceras) Fossil - Indiana

This is 1.9" wide fossil ammonite of the species Muensteroceras parallelum, collected from the Rockford Formation of Rockford, Indiana. The outer shell is gone leaving the chamber patterns exposed.

About Ammonites

Ammonites were ancient marine cephalopods, similar to today's squids and octopuses, but with a defining feature: their distinctive, tightly coiled spiral shells. These shells, resembling those of modern nautiluses, served as both a protective home and a buoyancy aid, allowing ammonites to navigate the prehistoric seas with ease. First emerging around 240 million years ago in the Triassic Period, ammonites thrived for over 175 million years, adapting through numerous forms and sizes. As predatory creatures, they likely fed on smaller marine organisms, using their tentacles to capture prey. However, their long reign came to an end 65 million years ago at the close of the Cretaceous, coinciding with the mass extinction event that also eliminated the dinosaurs.

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

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DETAILS
SPECIES
Muensteroceras parallelum
LOCATION
Rockford, Indiana
FORMATION
Rockford Formation
SIZE
1.9" Wide
CATEGORY
ITEM
#126192
GUARANTEE
We guarantee the authenticity of all of our specimens.