Species Regression: Roosters are Weak? I'm a Regressed Tyrannosaurus Rex

Earth Online has descended into another world, and each nation must select one participant to enter the game. Each participant must choose a creature to observe in antiquity on behalf of their nation. All selected creatures are released into an antiquated continent, where they will fight alongside their ancestors. The stronger the creature after antiquity, the greater its chances of survival, the longer it survives, and the more likely it is to win; conversely, the weaker it is, the more likely it is to fail, bringing natural disasters upon its nation. Towering elephants, incredibly fast cheetahs, the lion, the king of the grasslands… each creature possesses immense power. In this world where prehistoric biological knowledge is zero, and everyone believes that creatures strong now will be strong in antiquity, Bai Zhou didn't choose powerful carnivores like the other participants; instead, he chose the unassuming fighting rooster! Looking at the thin fighting rooster, the people of the Dragon Kingdom felt utterly hopeless. "Did I see wrong? Bai Zhou chose a rooster?" [It's over, we're going to be the first country to be eliminated!] Everyone thought fighting cocks would be the first species to go extinct, but as time went on, they discovered that fighting cocks grew larger and larger, their beaks transformed into mouths full of fangs, reverting to the form of a Tyrannosaurus Rex. Facing an attacking saber-toothed tiger, they simply roared and drove it away. Only then did they realize how wise their choice of fighting cocks had been. Tyrannosaurus Rex: Before the reversion, I didn't mind you calling me Brother Chicken, but after the reversion, what should you call me?