Fighting isn't an indication of a chick's sex. Males and females play and play at fighting to assert themselves into a fairly rigid social order. Marans can sometimes be a bit tricky, but I don't think I've ever had a pullet develop a comb or wattles that large so early. Additionally the legs are very thick, especially in the second image. Generally pullets don't show a lot of the red/copper in their hackles as quickly as cockerels. If you get any copper feathering in the saddle area you've most certainly got a young male.