I will give brainliest to whoever can answer this science riddle first and accurately :) I’m at the beginning of earth’s timeline, but at the end of life’s start. I was there when a T-rex began, but in the middle of it’s asteroid end. What am I?

I believee it's the Cretaceous Period?

All of the dinosaur periods are at the start of Earth's timeline, and "the end of life's start" suggests the end of dinosaurs, meaning, when the asteroid hit. So it's probably one of the Mesozoic periods.

The T-rex first appeared in the Cretaceous Period, and the asteroid hit somewhat during middle of the Cretaceous Period.

I hope I'm right, and I hope this helps!