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4.05" Highly Iridescent Fossil Ammonite (Sphenodiscus) - South Dakota
This is a 4.05" Sphenodiscus sp. ammonite specimen that was collected from the Fox Hills Formation of South Dakota. The shell is still intact and exhibits phenomenal iridescence. It's been wonderfully prepared free from the hard concretion it was found in.
There is a repaired crack with some minor gap fill and the ammonite has been coated in a thin layer of sealant/epoxy. It comes with an acrylic display stand.
There is a repaired crack with some minor gap fill and the ammonite has been coated in a thin layer of sealant/epoxy. It comes with an acrylic display stand.
These 70 million year old ammonites lived when South Dakota was a shallow inland sea. They were found preserved in concretions when split open. They then had to be hand-prepared to remove the hard rock surrounding them from their shells, a very time consuming task.
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.
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.
SPECIES
Sphenodiscus sp.
LOCATION
South Dakota
FORMATION
Fox Hills Formation - Trail City Member
SIZE
Ammonite 4.05" Wide
CATEGORY
SUB CATEGORY
ITEM
#144816
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