User blog comment:BradenJamesBingham/Dinosaurs are reptiles/@comment-3175425-20140901213735/@comment-2175601-20140922104902

Under phylogenetic taxonomy, dinosaurs are usually defined as the group consisting of Triceratops horridus, the house sparrow (Passer domesticus), their most recent common ancestor (MRCA), and all descendants. So, by definition birds are dinosaurs.