no......they aren't.......your assumptions link them together.....assumptions which cannot be proven scientifically......
the fact that a creature with nostrils in a certain location had teeth is not proof of transition between a creature that had teeth and a creature that had nostrils......its merely proof that there was a creature with nostrils in a certain location that had teeth.....
They are proof of transition in the line. There is NO alternative explanation for them and you have offered none.