Fig. 1From: The oldest described eurypterid: a giant Middle Ordovician (Darriwilian) megalograptid from the Winneshiek Lagerstätte of Iowa Pentecopterus decorahensis, prosomal ventral plate. a SUI 139914, posterior lobe of lateral portion of ventral plate. b SUI 139978, lateral portion of ventral plate showing carapace locking mechanism (arrowed). c SUI 139936, anterior portion of ventral plate including rostrum, retained on shale. d SUI 139936, posterior portion of ventral plate shown in Fig. 1c including linguoid projection, removed from sediment. e SUI 1139921, linguoid projection. f SUI 139917 part, ventral plate. g SUI 139917 counterpart, lateral portion of ventral plate. h SUI 139916, lateral portion of large ventral plate. Scale bars = 10 mmBack to article page