Mammals did not evolve fully before the dinosaurs. In the Triassic, the closest you get to a mammal is the cynapsids, or "mammal-like" reptiles. It's really first in the jurassic that some of the "actual" mammals showed up.

Birds are "avian" dinosaurs, that evolved from non-avian theropod dinosaurs.

Birds evolved from reptiles, yes. Birds (avian dinosaurs) evolved from non-avian dinosaurs, which evolved from the archosaurs, the first animals capable of bipedal movement. These archosaurs would also evolve into rauisuchians and eventually crocodiles.

Theropods are "three-toed dinosaurs". However some ornithischian dinosaurs also had three toes (mainly the smaller species). Usually theropods are in general associated with most of the carnivorous dinosaurs, but also a few omnivores and herbivores like Gallimimus.

Sauropods are in the order Saurischia (Meaning lizard hips, ironically enough considering the birds evolved from this order) yes. The order which is split in two; theropoda and saurpodomorpha. Sauropods started out as pro-sauropods, of which a lot of them were bipedal or at least could walk bipedal at times.


And yes, I am pretty interested in dinosaurs, as you perhaps would be able to tell just by my name.

I have my own big collection of teeth and bones from various dinosaurs, as well as a ton of fossils from other prehistoric creatures, including a partial Tylosaurus jaw. And in a few days, I'll recieve the frontal skull of a Sigilmassasaurus, which I am pretty damn excited for.

Could perhaps post some pictures of the collection some day, but we'll see.