3.1" Cretaceous Ammonite (Mortoniceras) in Situ - Texas

This is a 3.1" wide ammonite (Mortoniceras) from the Cretaceous, Fort Worth Formation in Texas. The ridges on the shell are well preserved and the suture lines look very nice. The fossil was partially exposed from the rock it was found in and makes for an excellent stand.


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
Mortoniceras sp.
LOCATION
Tarrant County, Texas
FORMATION
Fort Worth Formation
SIZE
Ammonite:3.1" wide, Entire specimen: 4 x 2.5"
CATEGORY
ITEM
#198224
GUARANTEE
We guarantee the authenticity of all of our specimens.