Answer:
1. Scientists have the evidence of fossilized dinosaur bones. These bones are similar to the bone structure of reptiles we know of today. Also, they have fossilized eggs, and reptiles reproduce with eggs.
2. Scientists know what dinosaurs eat by fossilized dinosaur feces. What goes in, must come out, and so by the nature of it being feces, they can tell what the dinosaur may have eaten. Depending on the type of dinosaur, some eat plants, some eat meat, and some eat both.
