They Shared the Stage

Mammals did not arrive after the dinosaurs left. The two groups lived side by side for over 150 million years, both getting their start back in the Triassic. Early mammals stayed small and mostly came out at night, dodging the reptilian giants that ruled the daylight.

Living in the dark for so long left a mark we still carry. Most mammals — humans included — see color worse than birds and many reptiles do. Our ancestors traded rich color vision for sharper night vision during those long dinosaur-dominated nights. We are still squinting through their compromise.