You can see the nice ceratitic suture pattern on this specimen with his smooth lobes and frilly saddles. The sutures would have increased the strength of the shell and allowed Ceratites (de Haan, 1825) to dive deeper, bearing the additional pressure of the sea in search of food.
Ammonite shells are made up predominantly of calcium carbonate in the form of aragonite and proteinaceous organic matrix or conchiolin arranged in layers: a thin outer prismatic layer, a nacreous layer and an inner lining of prismatic habitat. While their outer shells are generally aragonite, aptychus — those hard shelly plates you see — are distinct as they are composed of calcite.
These ammonites lived in open shallow, to subtidal and basinal environments some 247 to 221 million years ago. We've found them, thus far, in just over forty collections from nearly ninety fossil deposits around the globe. Fossils of species have been found in the Triassic of Austria, Canada, China, France, Germany, Hungary, India, Israel, Italy, Pakistan, Poland, Russia, Thailand, Turkey and the United States.
The parent taxon is Ceratitinae according to E. T. Tozer 1981. That's our own Tim Tozer, one of the great knights-errant of the Triassic timescale. Born a Brit but spent his life exploring the wilds of Canada and the Arctic Archipelago. It was Tim Tozer and Norm Silberling who published the classic milestones of the Triassic timescale, "Biostratigraphic Classification of the Marine Triassic in North America, Geological Society of America, Special Paper 110." The Global Triassic: Bulletin 41 from the New Mexico Museum of Natural History and Science by Lucas and Spielmann honours them in their work. Collection of Ange Mirabet, Strasbourg, France.
