Abstract Eocarcinus praecursor, the putative earliest member of Infraorder Brachyura of Early Jurassic age in Great Britain, cannot be accommodated within that infraorder. Numerous characters are inconsistent with placement within Brachyura, including: a lack of fusion of the epistome with the dorsal carapace; chelipeds on the first and putatively second pereiopods; lack of true orbits; development of large, strong antennae; notches in the carapace to accommodate the antennae; articulating rings on the pleomeres; development of prominent epimeres; and orientation of the chelipeds. Rather, E. praecursor must be referred to its own superfamily and family within Infraorder Anomura.