I sometimes get quite surprised with some of these debates I find in Helium. About things you consider as actual fact, there you find a debate. It's no need of mentioning how frustrating some of these debates are. Where people come forward with all these false facts whether due to their ignorance or pure dishonesty, I think I'll never know.
First of all we'll look at who these dinosaurs are. They are the most advanced reptiles ever to live on planet Earth, whom dominated the Mesozoic era (mainly the periods of Triassic and Jurassic) and then were extinct at the end of the Cretaceous period. They were the dominators in the Mesozoic era, with the domination of all three habitats; land, water and air. They were to be found all over the planet and looked unstoppable except for the giant asteroid which marked the end to one of the most fascinating chapters of life on Earth.
Then we'll come to birds. Birds were evolved in the Jurassic period, some 195 million years ago, in a time which was dominated by dinosaurs. At the same time the mammals were also evolved but unlike birds who quickly took over the Mesozoic atmosphere, the first mammals had a very tough life in a land ruled by giant dinosaurs. It was well after the Mesozoic era, after the dinosaurs were totally gone, the mammals actually came out of their underground hideouts, to a new world looked almost made for them to populate.
There are so many fossilize evidence to support the theory that birds were evolved from dinosaurs. Some of these fossils were a total mixture of birds and dinosaurs giving complete evidence to this theory. The fossil of Archaeopteryx one of the so called missing links between dinosaurs and birds is a great example to this. This fossil from the early parts of the Jurassic period has teeth like a dinosaur (mind that not a single bird has a single tooth) and feathers like a bird. It is clearly ironical that some people still deny all these evidence and try to live in a Dark Age situation. (It is also important to remember that we believe the humans and the modern apes had the same ancestor without a clear fossilize evidence like this one.)
Finally let us see what class Aves (which we normally call birds) and class Reptilia (to which the dinosaurs belong) has in common. Both these classes (under phylum Chordata) have the ability to lay eggs, which is a significant advantage they have when it comes to living in a dry habitat. Then the reptile skin is covered in scales as for birds, the scales can still be found in their legs, proving the evolutionary bond between the two classes. The skeleton structure too indicates some strong connection between the two.
The entire debate is made just because some people still clings to those middle age beliefs and keep on turning their back upon the theory of evolution. With all the evidence to support it, theory of evolution had continuously been criticized. It's a great shame as we are in the 21st century now. Unfortunately even with such a clear fossil like the one of Archaeopteryx people still debate about whether birds were evolved from dinosaurs. All I ask is when people will actually stop cheating themselves?