Pachydiscidae is a family of middle and upper Cretaceous ammonites in the superfamily Desmoceratoidea.
Morphology Pachydiscidae species are moderate to large in 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.
Pachydischidae evolved from Desmoceratidea, during the Lower Cenomanian, about the same time as the Kossmaticeratidae; however, they lived 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 Eopachydiscus Wright, 1955 Eupachydiscus Spath, 1922 Lewesiceras Spath, 1939 Menuites Spath, 1922 Nowakites Pachydiscus Zittel, 1884 Urakawites Matsumoto, 1955
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