The Paleo Atlantid type is a very archiac Northwestern sub type. It is probably one of the third oldest sub-type that is native to that part of Europe and it seems to have had its origins in the later part of the mesolithic period. This was a time frame in which the UP influences upon the British Isles and most of Northern Europe were quite considerable. The Paleo Atlantids absorbed some of the UP traits most likely of Alpinized Brunns/Borrebys. This probably added to their already robust Cro Magnonform configurment.
The Mediterranid influences might have occured near the time the Paleo Atlantids started showing up as a sub type in the British Isles and probably increased in influence into the Neolithic time frame. The North Atlantid type probably had influences on the Paleo Atlantid type slightly since they lived in close quarters to each other and it is possible that both sub-types Mediterranid strains might connect these sub types together back to the early Mesolithic time frame.
That said the evolution of the Paleo Atlantid types in Norway has probably developed a little differently than in the British Isles and is the result of an archiac Mediterranid Cro-Magnonform(Tydal) type probably merging with a UP Component like Borreby to create a heavier and stonier appearance to the type in Scandanavia. This type is very old throughout Northern Europe and unlike the Brunn which has survived not being altered by other types for the most part the Paleo Atlantid type has been altered by multiple Pre-Neolithic strains.