Two hundred million years after the solar collision innumerable species of sub-human grazers with long sheep-like muzzles, ample molars, and almost ruminant digestive systems, were competing with one another on the polar continent. Upon these preyed the sub-human carnivora, of whom some were built for speed in the chase, others for stalking and a sudden spring. But since jumping was no easy matter on Neptune, the cat-like types were all minute. They preyed upon man's more rabbit-like and rat-like descendants, or on the carrion of the larger mammals, or on the lusty worms and beetles. These had sprung originally from vermin which had been transported accidentally from Venus. For of all the ancient Venerian fauna only man himself, a few insects and other invertebrates, and many kinds of micro-organisms, succeeded in colonizing Neptune. Of plants, many types had been artificially bred for the new world, and from these eventually arose a host of grasses, flowering plants, thick-trunked bushes, and novel sea-weeds. On this marine flora fed certain highly developed marine worms; and of these last, some in time became vertebrate, predatory, swift and fish-like. On these in turn man's own marine descendants preyed, whether as sub-human seals, or still more specialized subhuman porpoises.
Source: tatoeba (8858009)