The ornamental design for a squaredstaircasebaluster, as shown and described.
FIG. 1 is a side elevational view of a squared staircase baluster showing
my new design, the broken line showing is for illustrative purposes only
and forms no part of the claimed design; and
FIG. 2 is an end elevational view thereof, the broken line showing is for
illustrative purposes only and forms no part of the claimed design.