Final answer:
Andorra had a joint sovereignty with the French Count of Felix and the Spanish Bishop of Seu d'Urgell and was independent in 1278.
Step-by-step explanation:
The country that had a joint sovereignty with the French Count of Felix and the Spanish Bishop of Seu d'Urgell and was independent in 1278 was Andorra. Andorra is a small principality located in the eastern Pyrenees mountains between France and Spain.