[Oztrich Boy]

I have a science question: why were carnivorous dinosaurs bipedal?

Wrong question. The proto-dinosaurs were carnivorous and bipedal. It's a legacy thing. This question is the development of vegetarian diet and quadripedalism,

[curiosity]

The proto-dinosaurs were carnivorous and bipedal.

Wait a minute. If proto-dinosaurs were bipedal and carnivorous, what did they eat? There must have been some contemporaneous herbivorous proto-dinosaurs, no? Or did they they ate herbivors of a different order/phylum?

[curiosity]

Acording to this article, the reptile ancestors of dinosaurs were quatripedal, which then evolved into the first dinosaurs, which were bipedal, both herbivore and carnivore. Then the herbovores became quardripedal again. Fascinating.

http://microlnx.com/dinosaurs/Bipedality.html