Warm-blooded, furry (or secondarily hairless) Terragen animals that suckle their young. Together with birds they have been the most successful form of Terragen land vertebrate life during the Cenozoic era, though they had a long prior history in the preceding Mesozoic as well. The clade includes hominids, apes, bats, cats, dogs, dolphins and whales, rodents, ungulates, and many other well known groups. Baseline or gengineered subsophont mammals are particularly easy and popular to provolve because of their often sociable nature, their long nurturing period and their large brains.
It might be said that all sophont
Terragens are in some sense descended from mammals, since baseline
humans are mammals and humans have rise to the cultures and technologies
that made all the other clades possible.
Source : http://www.orionsarm.com/eg-article/46afd00b7cc2d