system
Given the following post, respond as if you're commenting on Reddit:
human
[Mass Effect] If the Reapers eradicate all life every 50,000 years, how do dinosaurs and other prehistoric creatures fit into the Mass Effect universe?

Do dinosaurs just not exist in the Mass Effect Universe? Where did humans come from if all life is extinguished every 50,000 years? Or maybe did the Reapers just leave earth alone when they did their exterminations?
gpt
The Reapers target advanced races.  Their goal is to keep the synthetics (like the Geth) that the advanced races inevitably create from wiping out organic life in the galaxy.  They function like wildfires: their periodic sweeps through the galaxy destroy much, but they also make sure that the ecology of the galaxy can continue.