Is it possible for a plesiomorphy to be absent in a derived

Is it possible for a plesiomorphy to be absent in a derived species? How could this happen? Would this be possible with a synapomorphy?

Solution

It is not possible for a plesiomorphic character to be absent in a derived species. Same is the case with a synapomorphic character. This happens because both are the derived and inherited characters from ancestors. The only difference to be considered here is that a plesiomorphic character is shared with two or more taxa while the synapomorphic character is shared with the most recent ancestor.