One of these State of Qatar seals is not like the others

The state seals below are from Qatar money in a private museum here in Qatar from the the past to the present, from the oldest on the left to the most recent on the right. What you will notice is that the oil rig on the oldest seal has dissappeared in subsequent seals including the present seal. What does this mean? Identity of state includes sanitizing/disappearing the past? Was the oil rig seen as a western symbol or just one that didn't fit into the image of who/what the country should be? Are the symbols of the dhow ((the boat) and palm tree more authentic or are they idealistic whereas the oil rig is realistic. One interesting thing to note is that the sails on the dhow have changed from an authentic three sails to a symbolic/idealistic one sail. One other interesting thing to note is that the fishing industry whose symbol is the dhow is not the primary industry anymore...that would be oil production, yet the symbol for oil production has been taken off the state seal.