Get outside Great Britain, and look at such places as Puglia (squared menhirs, often tipped slightly; two styles of dolmen uprights absolutely congruent with the structural capabilities of local atone), the Languedoc (unique for its statue menhirs), Carnac (the fanning rows), Gobekli Tepe (t-shaped, sculpted stones in a radial pattern). Certainly there were regional styles of megaliths. These styles seem to me to have arisen fullblown: there aren't any trial periods, or examples of simpler "generic" models evolving into more explicitly regional ones.

It seems clear to me Mesolithic peoples had distinct local cultures that adapted the *idea* of "megalith" to their own local ideas of beauty and function. What, of course, those local ideas were remains pretty obscure.