Hapoloceratoid ammonite and Lamellaptychus

Jurassic

Solnhofen Limestone

Solnhofen, Germany.

48mm haploceratoid ammonite with 19mm aptychus on 97mm matrix.

Ammonite.  Cephalopod.

Hapoloceras is an ammonite genus known from the Jurassic of Europe.  “Hapoloceratoid” means an ammonites similar to Hapoloceras.

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.