[Nebullis]

Dinosaurs were not reptiles.

Dinosaurs are reptiles. Not all reptiles are dinosaurs.

[capitan_refugio]

You are right, and you are wrong. Modern reptiles include only the turtles, snakes, lizards, crocodiles (and relatives), and the tuatara. These comprise the orders Chelonia (turtles and tortoises), Squamata (snakes,lizards, and amphisbaenia), Crocodilia (crocodiles, caimans, alligators, and gavials), and Rhynchocephalia (tuataras).

True dinosaurs fells into the orders Saurischia and Ornithischia (bird-like dinosuars). Other important extinct orders contained the Pterosauria (pterydactyls, etc.), Ichthyosaurs and Sauropterygia (aquatic reptilians), and Placodontia. There are several other less important orders.

All of these orders (living and extinct) belong to the class Reptilia. They are properly referred to as "Reptilians." When you use the term "reptiles" today, most herpetologists (scientists who study reptiles and amphibians) will assume you are talking about the four modern orders.

It is also important to note, as in an earlier post, the bone structure of many of the dinosaur genera suggest warm-bloodedness (i.e. much more bird-like than reptile-like).

The long and the short of it is that both statements are correct - from a point of view.

[Maceman]

Dinosaurs are reptiles. Not all reptiles are dinosaurs.

As I say, reptiles are cold blooded, and dinosaurs were not. Therefore, dinosaurs were NOT reptiles, although they had been mistakenly classified as such since their first discovery in the 1700s.