preabdominal

As such, Megalograptus has been considered to represent the plesiomorphic condition within eurypterids for a number of characters, including the occurrence of the opisthosomal preabdominal/postabdominal constriction at the sixth and seventh segment as opposed to the seventh and eighth [ 5 ], the possession of an extra podomere on prosomal appendages II–V [ 72 ], and the morphology of the prosomal ventral plates [ 37 ].