Lamellaptychus

Jurassic

Solnhofen Limestone

Solnhofen, Germany.

30mm aptychus of a haploceratoid ammonite on 82mm matrix.

Ammonite.  Cephalopod.

Lamellaptychus is a genus erected for an aptychus form not associated with a particular ammonite taxon.  An aptychus is a shelly plate sometimes found in pairs that has been interpreted as an opening and closing structure at the aperture of the ammonite shell and/or a part of the jaw structure.  Aptychi are usually found separated from the shell but sometimes found preserved inside it.  Paleontologists find them throughout the fossil record of ammonites all the way to the end of the Cretaceous.