Echinoidea - Cassiduloida - Cassidulidae
Alternative spelling: Rhynchopygus
Parent taxon: Cassidulus according to W. S. W. Kew 1920
See also Clark and Twitchell 1915, Grant and Hertlein 1938, Holmes 2004, Kier 1962, Kier 1966 and Sepkoski 2002
Sister taxa: Cassidulus (Cassidulus), Cassidulus (Galerolampas), Cassidulus abruptus, Cassidulus amygdala, Cassidulus caribaearum, Cassidulus gouldii, Cassidulus mercedensis, Cassidulus rojasi, Cassidulus yoshiwarai, Nucleolites (Cassidulus) elatus
Subtaxa: Cassidulus (Rhynchopygus) californicus Cassidulus (Rhynchopygus) depressus Cassidulus (Rhynchopygus) ellipticus Cassidulus (Rhynchopygus) evergladensis Cassidulus (Rhynchopygus) mexicanus Cassidulus (Rhynchopygus) ynezensis Rhynchopygus arumaensis Rhynchopygus lapiscancri Rhynchopygus marmini Rhynchopygus peruvianus
Distribution:
• Quaternary of United States (2: Florida collections)
• Miocene of Mexico (1), United States (1: North Carolina)
• Eocene of Peru (1), United States (7: California, Georgia, North Carolina)
• Cretaceous to Paleogene of the Netherlands (1)
• Cretaceous of Belgium (1), the Netherlands (2), Saudi Arabia (1), Spain (2)
Total: 19 collections each including a single occurrence