Pachydiscidae

Pachydiscidae Temporal range: 99.6–65.5 Ma PreЄ Є O S D C P T J K Pg N - Albian - Maastrichtian
Eupachydiscus isculensis from Cretaceous – Bergamo (Italy)
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	Ammonoidea
Order:	Ammonitida
Superfamily:	Desmocerataceae
Family:	Pachydiscidae Spath 1922

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.

Genera

• Anapachydiscus † Yabe and Shimizu 1926
• Baskaniceras † Wright and Kennedy 1984
• Canadoceras † Spath 1922
• Eupachydiscus † Spath 1922
• Lewesiceras † Spath 1939
• Menuites † Spath 1922
• Nowakites †
• Pachydiscus † Zittel 1884

Distribution

Fossils of Pachydiscidae are found in the Cretaceous marine strata throughout the world, including Angola, Antarctica, Armenia, Australia, Austria, Belgium, Brazil, Bulgaria, Chile, Czech Republic, Denmark, France, Germany, Haiti, India, Jamaica, Japan, Mexico, Netherlands, Nigeria, Oman, Russia, South Africa, Spain, Turkey, United States and Uzbekistan.

References

• Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology, Part L (1957), p L377-L380. Geological Society of America.
• Paleobiology Database