Cauda galli \Cau"da gal*li\, . [L., tail of a cock.] (Paleon.) A plume-shaped fossil, supposed to be a seaweed, characteristic of the lower Devonian rocks; as, the cauda galli grit. {Cauda galli epoch} (Geol.), an epoch at the begining of the Devonian age in eastern America, so named from the characteristic gritty sandstone marked with impressions of {cauda galli}. See the Diagram under {Geology}.