Weird. It really has no
spring, just bends over to form a pin. A crude bird or
pelta manufactured by some local smith or soldier-blacksmith?? So crude and unique that it is hard to tell age. But iron
fibulae were relatively
rare in
Roman times and more common in late
celtic (unlikely here) or post-Roman -
Byzantine and Germanic from 6th-7th c. Maybe that is when this fits in but that is just a guess.
SC