The dinosaurs once had a democratic form of government which then became a large, educated and scientifically advanced republic. Eventually, wealthy dinosaurs began to game the system until the meritocracy that had made the dinosaurs prosper fell into ruin as inbred and entitled bloodlines inherited rule. Through this nepotism, they appointed morons to head their armies and nations as they wanted blind loyalty over ability. They waged endless wars and made horrible music videos. Eventually, the dinosaurs learned to split the atom and nuclear bombs were created. Believing the concept of mutually assured destruction would keep the ruling inbred dipshits from starting a global nuclear war, they launched a massive exchange of ICBMs and completely wiped themselves off the face of the earth.
The mystery is over. You’re welcome.