In many bird and mammal species, males are significantly larger than females. The prevailing explanation for larger-sized males is that sexual selection drives increased male size. In addition, researchers commonly assume that the extent of dimorphism indicates the strength of selection for increased size in males. Here, through reconstruction of ancestral morphology for males and females of on...

The muskrat (Ondatra zibethicus) lives in both modern and prehistoric wetlands. Sexual dimorphism is a characteristic of many species that is relevant to both modern behavior, such as the partitioning of resources, and the accurate assessment of fossil populations. If sexual dimorphism is present in muskrats, what is known about their interaction with the environment may be inaccurate, as could...