576303.fig.002a
(a)
576303.fig.002b
(b)
Figure 2: (a) Examples of male polyphenism in O. taurus (top) and O. nigriventris (bottom). Large males are shown on the left and small males on the right. Note that females (not shown) are entirely hornless in both species. (b) Rare reversed sexual dimorphism in O. sagittarius. Males also lost ancestral male dimorphism.