4.8" Wide Ammonite Cluster - South Dakota

This is a 1.9" Sphenodiscus ammonite specimen from the Fox Hills Formation of South Dakota. It's been nicely prepared from the hard concretion in which it was found and the base is flat enough that it will display nicely without the use of a stand. This ammonite has a number of "friends" still buried in the rock. The entire piece measures 4.8 x 3.7"

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
Sphenodiscus
LOCATION
South Dakota
FORMATION
Fox Hills Formation
SIZE
Largest Ammonite 1.9" Wide, Rock 4.8 x 3.7"
ITEM
#98707
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