Good question!
Most scientists these days think that birds ARE dinosaurs, and that birds (as indeed all dinosaurs) ARE reptiles. These ideas might sound crazy at first, but there's lots of evidence to back them up. Evidence from fossils has shown that birds are as much dinosaurs, as poodles are dogs. Even though birds have many unique qualities relative to other dinosaurs, and poodles are special compared to other dogs, birds ARE dinosaurs and poodles ARE dogs just the same. So to get back to your question, there are many feathered dinosaurs that "bridge the gap" between birds and the non-feathered dinosaurs--just as non-bird-dinosaurs "bridge the gap" between birds and the nearest reptilian relatives of dinosaurs. Good luck with your investigation.

Birds are living dinosaurs.
The definition of a reptile is argued by biologists. Some say that dinosaurs are a kind of reptile, which means that birds are also a kind of reptile, since birds are a kind of dinosaur. Others separate birds from reptiles. It's a question of word definitions, and words are something that human beings make up so that we can talk about stuff. Nature doesn't have to abide by our words.

The closest living relatives to birds are crocodiles and alligators. They are more closely related to each-other than they are to lizards, snakes, or turtles.