The caudal limb of the postcentral is joined by a transparietal piece.
So they got more tail and spliced it on to his caudal appendage.
He named it falcata, or "scythe-shaped," from the curving of the caudal fin.
The caudal extremity of both is furnished with a rudimentary claw.
This brings you to where the dorsal and caudal fins are inserted.
They are last traceable ...