Complex sentence: Henry Baker Tristram (1867) proposed it to be the Saharan antelope addax and described it as a large animal, over 3½ feet high at the shoulder, and, with its gently-twisted horns, 2½ feet long.
Split into simpler sentences: Henry Baker Tristram (1867) proposed it to be the antelope Addax. It is described as a large animal, over 3½ feet high at the shoulder, and, with its gently-twisted horns, 2½ feet long.