The Fracture. Dominion Earth: The Saurian Wars, #1

Sixty-five million years ago, Earth was not a chaotic wilderness-it was a planet divided into dynastic empires ruled by sentient dinosaur species. Each species evolved its own culture, technology, and philosophy, locked in a cold war of ideology and survival. In this world, the Rexan Dominion, a brutal monarchy of honor-bound warriors, rules supreme. But when a celestial anomaly is detected, threatening planetary extinction, the Rexan Dominion sees it as a divine test.
Meanwhile, the Raptari Syndicate, a collective of master tacticians, uncovers ancient tech that could deflect the threat. As tensions rise and alliances fracture, a war looms that may determine if the planet will unite or perish.