Clymeniida

Clymeniida is an order of ammonoid cephalopods from the Upper Devonian characterized by having an unusual dorsal siphuncle. They measured about in diameter and are most common in Europe, North Africa, and South China but are known from North America (New York, Ohio, Oklahoma, and Utah) and Australia (New South Wales) as well.

== Morphologic characteristics == Clymeniids produced a variety of shells ranging from smooth to ribbed and spinose, from evolute with all whorls exposed to strongly involute with the last whorl covering the previous. Some were even triangular in lateral view. With the exception of the first few chambers, all have a siphuncle that runs along the dorsal margin, i.e., along the inner edge of each whorl, rather than the outer edge as in most ammonoids.