@spooky24,
There are 5 classes of vertebrates, Reptiles and Birds are two separate classes. the common ancestor of the dinosaur- to- bird class was probably a Maniraptoran , which was actually a member of the "lizard hipped" theropod dinosaurs (Saurichians), and NOT , as many first thought, from the "bird hipped" dinosaurs (The ornithischians).
Birds arose as one of the 5 classes of vertebrates. Dinosaurs are still in the reptile clade . The classes are the fish, amphibians, reptiles, birds, an mammals.
SO, indeed, the bird arose from dinosaurs but, by virtue of about 40 to 50 significant differences (like some dinosaurs had beaks but NO birds had teeth). Archeopteryx was, indeed, a transitional fossil. It retained 20 or more "Lizard like features" while introducingabout 15 "birdy features"
I herd that line in the first Jurassic Park but theres about 5000 academic paleontologists who would differ with "Dr Sam".
Theres some new dinospeak about the original reptile/bird transitional fossil(
Longisquama) from the Triassic , not the Jurassic. Im sure more will be published, kids gotta eat.