From the earliest reptiles, cotylosaurs, who branched out into pelycosaurs, who gave rise to the mammal-like therapsids, among whom were several plant-eating anomodonts and various meat-eating theriodonts. . . well, around the time of brachiosaurus, allosaurus, and the other dinosaurs, from those therapsids emerged --at last!--tiny mammals. Among those that survived the Jurassic (we'll skip some that didn't) were the pantotheres; and from them came, eventually, today's monotremes, marsupials, and placental mammals. It's not just a string of long names; Ricciuti does present the evolutionary changes as adaptations. Still, some sorting out and hanging on is required to follow him this far, which happens to be about a third of the way through the book. The second third, on the age of mammals, is easier to follow, with ancestors of familiar animals emerging and with the mammals' divergent development viewed in the light of continental drift. When Ricciuti gets to the Ice Ages, he uses the findings at the La Brea Tar Pits as the basis for a more vivid and dramatic recreation of mammalian life as it was then; and his last chapter on early primates has the advantage of its narrower focus. With up-to-date information that supersedes earlier mammal books, this could serve as a useful reference for studious kids--and they do exist--who like to see the separate pieces laid out in order. (They'll just glide over the tacked-on, obligatory regrets about today's endangered mammals.) The casual prehistoric-monster audience attracted by the readable-looking format won't survive the Age of Reptiles.