Oeste do Éden, de Harry Harrison (primeiro livro de uma trilogia do Éden).
In the parallel universe of this novel, Earth was not struck by an asteroid 65 million years before the present. Consequently, the Cretaceous–Tertiary extinction event which wiped out the dinosaurs and other reptiles never happened, leaving the way clear for an intelligent species to eventually evolve from the mosasaur, a species of reptile related to the modern monitor lizards. This relationship would mean that the intelligent species are not dinosaurs but lizard-people.
The lizard-people are known as the Yilané, and are the dominant life form on most of the planet. However, during the evolutionary process, the species became non-viable on the two American continents, leaving them free of Yilané for millions of years and opening an ecological niche for a top predator. A human-like species, the Tanu, evolved to fill the niche in North America, but are only found on that continent. By the time the novel begins, the humanoids have reached a late stone age level of technology and culture, with a number of societies having developed farming skills.
The Yilané, having had millions of years of civilization, have a very advanced society primarily based on a mastery of the biological sciences, especially genetic engineering, so much so that almost every tool and artifact they use is a modified lifeform. Their boats were originally squids, their submarines are enhanced ichthyosaurs (here called uruketos), and their guns are evolved monitor lizards which eject projectiles using pressurised gas.