Depending upon who you ask, the common belief on right posture for meditation begins with a straight back and legs crossed lotus style. Nothing could be further from the truth.
Meher Baba lay down to meditate, Osho sat in a comfortable chair, and Krishnmurti walked. And if you research the Zen masters, meditation happens when chopping wood, carrying water, or releasing an arrow.
There is no right or wrong posture for meditation, there is only what works for you.