import maya.cmds as mc
lsT=mc.ls(type="transform")
Group=[]
for i in lsT:
lsS=mc.listRelatives(i,shapes=1)
if(not lsS):
if mc.nodeType(i)!="joint":
Group+=[i]
for s in Group:
mc.select(s,add=1)
lsT=mc.ls(type="transform")
Group=[]
for i in lsT:
lsS=mc.listRelatives(i,shapes=1)
if(not lsS):
if mc.nodeType(i)!="joint":
Group+=[i]
for s in Group:
mc.select(s,add=1)