Until just a few years ago, scientists were convinced that the dinosaurs who lived on earth many millions of years ago were reptiles, related to modern snakes and lizards. But recent discoveries have made these same scientists wonder exactly what kind of creature the dinosaur really was.
First of all, they still do not know whether the dinosaur was cold-blooded, a reptile, or warm-blooded, like a bird or mammal. Skeletons of baby dinosaurs, found in a nest, suggest that the young were fed by their mother for many months after birth. Today, only warm-blooded animals take such a long-term interest in their offspring.
Secondly, these scientists found that dinosaur bones resemble the bones of mammals and birds, more than they do those of reptiles. And many dinosaurs probably stood upright on two legs, while no living reptile stands erect.
The scientists who believe that dinosaurs were warm-blooded creatures claim that these giants never really died out, but instead evolved into modern animals.