Reported there are cased of elongated skulls that are not the result of cranial deformation techniques (along side many examples that are) . Wild speculation arises to the cause, but I'm going to burst the bubble on the alien /x/ rejects.
It is far more likely if these natural skulls are real they are the result of the admixture between homo sapiens and neanderthals resulting in birth cranial movement that would change the trajectory of the sloped neander skill born through smaller homosapien vaginal cavity.
These eventually are then bread out as it likely faced higher infant mortality rates.