LAS VEGAS – All the pre-fight activities are in the books for UFC Fight Night 211 following Friday’s official weigh-ins and faceoffs. In the main event, Mackenzie Dern (12-2 MMA, 7-2 UFC) takes on Yan Xiaonan (15-3 MMA, 6-2 UFC) in a key women’s strawweight bout. In the welterweight co-feature, Randy Brown (15-4 MMA, 9-4 UFC) meets Francisco Trinaldo (28-8 MMA, 18-7 UFC) At the conclusion of the official weigh-ins, the fighters came face to face for final staredowns. Check out the highlights in the video above and a photo gallery from the weigh-ins and faceoffs below. UFC Fight Night…