AMM276 Ammonite in Matrix (South Dakota)

This ammonite specimen comes from South Dakota during the Cretaceous period when the area was submerged by the Western Interior Seaway millions of years ago. They are typically preserved in hard concretions that must be carefully removed. This fossil shows the ammonite partially within its matrix as it was naturally found, with treatment where it joins on the back to increase stability. The ammonite has well-preserved ridges and a mostly intact pearly outer shell layer with strong rainbow iridescence. A small section on the back where the shell is eroded shows leafy suture patterns. Approx. 2.5" x 1.5" x 1.25"2.9oz (82g) Ammonites are prehistoric nautilus related to the modern day nautilus, squid, and octopus family. These squid-like creatures lived in the sea between 65 - 415 millions years ago. Ammonites are called cephalopods because their heads and tentacles protruded out of the same opening; they grew by building larger chambers on their shells. Some species have been found at alm