[dinosaur] Why birds are living dinosaurs

[Poekilopleuron <dinosaurtom2015@seznam.cz>]

Good day!

If you were to answer this question, how would you put it? Because birds evolved directly from the dinosaurian ancestors? Because they still carry the dinosaur genetic heritage? Because they are in fact a specialised group of living maniraptoran theropods? I've heard some people say ignorant things like "birds can not be dinosaurs, because they are so different, mostly very small and there is no way that such an agile warmblooded insulated animal could be a descendant of something like T. rex".

Thank you for your thoughts! Tom