Reptilia.
Linnean classification of extinct animals is difficult and is always changing. Some paleontologists have advocated to create a separate class for dinosaurs, pterosaurs, crocodiles and birds called Archosauria (currently Archosauria is a subclass of Reptilia), although the prevailing opinion in the scientific community is that dinosaurs and their kin remain in Reptilia.
Dinosaur
Stegosaurus was a dinosaur, which would put it in the class reptilia. Some, however, have proposed moving dinosaurs to their own class.
most people think there reptiles
That would be 'Therapoda', the same group that Tyrannosaurus rex belonged to.
One class of dinosaurs is still alive today: birds.
Dinosaurs belong to the clade Dinosauria. The old kingdom/phylum/class etc. divisions have come to be regarded as more a detriment than a help to taxonomic classification.
Dinosaur cat dinosaur dinosaur dinosaur mat.
dinosaur dinosaur dinosaur
Dinosaur fish dinosaur dinosaur.
Dinosaur 35 is arrhinosaurus.
under the dinosaur
Velociraptor was technically a reptile, though its traits were not very reptilian. It was a dinosaur belonging to the clade Theropoda and the family Dromaeosauridae.