It is a common misconception that archaeologists are only interested in Indian history. Archaeologists are interested in the human story through a study of the things they left behind. In North America, that involves both the Indian and the Euro-American cultures. In other parts of the world, archaeologists study the history of the people who lived there. As for dinosaurs, those studies are left in the capable hands of the paleontologists.
Paleontologists study the fossils of extinct animals, including dinosaurs.
Taking artifacts without using proper scientific methods destroys irreplaceable evidence from the past. Federal and state laws do not allow the removal of artifacts from public lands without a permit.