What is the difference between a bird and a dinosaur?

There are literally only two consistent differences, and they have nothing to do with feathers or beaks: Birds are simply dinosaurs with fused fingers and a pygostyle. read more

Dinosaurs have more variety than the bird do as a dinosaur can be an animal such as anklyosaurus or utahraptor. Dinosaurs have a vastly wider form than birds do. An easy way to think of it is parrots are a type of bird while not covering all birds. read more

Some differences between birds and dinosaurs are dinosaurs are cold-blooded reptiles, and they have scales as an outer covering, while birds are warm-blooded, and have feathers as an outer covering. read more

Other arguments, such as the putative differences between theropod and bird finger development, or lung morphology, or ankle bone morphology, all stumble on the lack of relevant data on extinct theropods, misinterpretations of anatomy, simplifying assumptions about developmental flexibility, and/or speculations about convergence, biomechanics, or selective pressures. read more