Cretaceous Fossil Ammonite Cluster - South Dakota

This is a fossil ammonite cluster from the Fox Hills Formation of South Dakota. It's been wonderfully prepared on the hard concretion it was found in. It contains a 1.7" Hoploscaphites nicolletti, a 2.9" Hoploscaphites spedeni and a 1.2" Discoscaphites gulosus. The total height of this cluster is 3.2" In addition to the ammonites, there are a number of fragments and shells still partially concealed in the stone. The ammonites are iridescent and stand out nicely against the dark stone.

There are crack repairs through the Hoploscaphities nicolletii and both the Hoploscaphites spedeni and Discoscaphites gulosus ammonites were removed from the rock, prepped and then remounted to the original portion of the rock they were found in.

Ammonites were predatory cephalopod mollusks that resembled squids with spiral shells. They are more closely related to living octopuses, though their shells resemble that of nautilus species. True ammonites appeared in the fossil record about 240 million years ago during the Triassic Period. 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.
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DETAILS
SPECIES
Hoploscaphities nicolletii, Hoploscaphites spedeni, Discoscaphites gulosus
LOCATION
South Dakota
FORMATION
Fox Hills Formation
SIZE
1.7" H. nicolletti, 2.9" H. spedeni, 1.2" D. gulosus, 3.2" tall
ITEM
#115363
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