Why didn’t the dinosaurs recover?

Question

Why didn’t the small post apocalypse survivor dinosaurs just refill the niches? Did the asteroid alter the planet in some way fundamentally different than the prior 200M years?

Edit: (collaborative clarification with my 5yo, with paraphrasing): Birds are boring dinosaurs. Why didn’t the big dinosaurs (non bird) come back? Why are there no mammal-sized (non bird) dinosaurs? (e.g., mouse through elephant-sized or even whale size)

In: 77

Answer 1

After the Asteroid Hit, earth was changed Forever. Les Oxygen in the Atmosphere, an ice age caused by the Tons of dust and smoke in the Atmosphere. Most Things just died, like the surviving big dinosaurs That just couldnt Find enough to eat. And now 65 Million years later we have Humans…