Scientists know that dinosaurs laid eggs because ?

As far as we know, all dinosaurs reproduced by laying eggs, as do most other sauropsids (reptiles). It is very difficult to determine what species of dinosaur laid the eggs that have been discovered, because only a few dinosaur embryos have been found inside the fossil eggs.

They are the early age birds.

Explanation: Cavemen lived before us and there Neanderthol was born way before then.

it marks things for degradation via the proteasome. it alters there celluar location.