oh yeah. But the believe is that actually the cubones are the babies that sit in the pouches of the Kangaskan, and you can't tell its them because they have a mask on the entire time. which very easily could be the skull of a dead kangaskhan. because otherwise they match up pretty well.
kind of like. oh what is it... shellder is gastly with a shell?
Except this is the new mega kangaskhan
and the theory was based on what it looked like in the pouch. Which technically the belly could have been given something because of the megastone.
and here is Cubone

original khangaskhan baby.
so really it could just be evolution.