the larger species, "r. giganticus", is the largest mammal known from the cretaceous. "r. giganticus" was more than 1 metre (39 inches) long and weighed about 12–14 kg (26–31 lb). its skull measures 16 cm (6.25 in) long, its body 52 cm (20.5 in), and the preserved part of its tail 36 cm (14 in).