>>13301195Loss of vegetation meant the only reliable food sources were meat and eggs. This meant a shitton of egg poaching, and thus a shitton of selection for minimal incubation time, which meant a shitton of selection against teeth. The vast majority of, if not all, land animals that survived the extinction event had evolved to be born without teeth.
To put the issue into perspective: if humans were born with all their teeth, the average pregnancy would last over 3 years.
Mammals have internal gestation with lactation so they were on easy street to dominate via live birth and milk rearing until teeth development.
Birds had beaks to reduce incubation time, and were able to hide their eggs in hard to reach places thanks to flight.
Monotremes were flightless egg layers and functionally went extinct, but the handful that survived have beaks.
Turtles and alligators both hide their eggs, and alligators are incredibly protective of their young, carrying them in their mouths which is likely why they were able to survive and keep their teeth.
Dinosaurs as we know them were flighless, tooth-having motherfuckers with long incubation times and poorly guarded nests. They likely god raided non-stop by early mammals and died out pretty fast.
