The hindlimb hypertrophy and augmented power in the limb extensor musculature of bipedal rodents, like kangaroo rats and jerboas, hypothetically better equip them to escape depredation than their quadrupedal counterparts. Visualizing and measuring hindlimb musculature allows us to better understand the differences that elicit rapid responses in bipedal rodents needed to escape from incoming predators. We used DiceCT and digital segmentation to visualize and measure the volume of the ankle extensor muscle of 14 rodent species, representing two bipedal lineages alongside quadrupedal outgroups. Generally, bipedal rodents had larger ankle extensors relative to their body size. For example, Dipodomys ordii, a North American Heteromyid, has the most massive lateral gastrocnemius relative to body size. However, Napaeozapus insignis also has large ankle extensors relative to body size. They represent an “intermediate” between quadrupeds and bipeds and are known for explosive jumps. We report a reduced or absent soleus muscle in bipedal Dipodidae. Our data supports the hypothesis that bipedal rodents have larger and thus more powerful ankle extensor muscles that facilitate powerful leaps in order to escape from potential threats such as those from an owl or rattlesnake attack. We propose that bipedal hopping likely coevolved with larger ankle extensors to perform these explosive, high-powered jumps. We contrast the putatively convergent morphological adaptations of kangaroo rat and jerboa lineages and discuss their evolutionary trajectories relative to quadrupedal counterparts.