Pachydiscidae
Encyclopedia
Pachydiscidae comprise a family of middle and upper Cretaceous ammonites (order Ammonitida
) which makes up part of the Desmocerataceae.
Pachydiscidae are of moderate to large size, evolute to rather involute, and vary in section from inflated and depressed to high-whorled and compressed. They are distinguished from the Desmoceratidae
by strong ribbing at some growth stage, that normally crosses the venter uninterrupted, and by the tendency to develop strong tuberculation, at least on the umbilical shoulder.
The Pachydischidae are derived from the Desmoceratidea, in the upper Albian, about the same time as the Kossmaticeratidae, but extend further into the Maastrichtian, virtually to the end of the Cretaceous.
Ammonitida
The Ammonitida is an order of more highly evolved ammonoid cephalopods from the Jurassic and Cretaceous time periods, commonly with intricate ammonitic sutures....
) which makes up part of the Desmocerataceae.
Pachydiscidae are of moderate to large size, evolute to rather involute, and vary in section from inflated and depressed to high-whorled and compressed. They are distinguished from the Desmoceratidae
Desmoceratidae
Desmoceratidae is a family belonging to the ammonite subclass. They are an extinct group of ammonoids, shelled cephalopods related to squid, belemnites, octopuses, and cuttlefish, and more distantly to the nautiloids.-References:* accessed on 10/01/07...
by strong ribbing at some growth stage, that normally crosses the venter uninterrupted, and by the tendency to develop strong tuberculation, at least on the umbilical shoulder.
The Pachydischidae are derived from the Desmoceratidea, in the upper Albian, about the same time as the Kossmaticeratidae, but extend further into the Maastrichtian, virtually to the end of the Cretaceous.