Question: Taking several notable real life inspirations from the animal kingdom I like to design a realistic Dragon towering any creature ever lived but has a nasty habit of generating sonic boom every where in its wake. What are the prerequisites my Dragon have to evolve in order to attain supersonic flight? 

I think it's must have close to a mammal blood circulation to supply ample oxygen to its already effective muscular system and is warm blooded like a cheetahs to give it energy for sudden rush of adrenaline, a crocodiles eyelids to cover it eyes, and so on. My concern is that this colossal winged breast would be too heavy and its skeletal structure have to be augmented naturally through evolution but I have no clues how any animal can survive unhurt after performing such a earth shattering feat any ideas? No tech pls and absolutely no thunderpants!

Answer: 
I was going to post this as a comment on @Zibbobz's answer, however it kind of grew to being its own answer.

If there was some local fauna which was kind of like kelp. With pockets of hydrogen gas to help hold it's self up. The plant would have evolved this to help them scatter their seeds or pollen over a very large area. 

When the dragon wants to go hunting it grabs hold of lots of these. Cuts them free of the ground and floats up, up and away. These plants will have evolved to have very stretchy gas sacks so they can reach higher altitudes. (a normal weather balloon can stretch four times its size during flight[1](http://www.diyspaceexploration.com/introduction-to-high-altitude-balloons/)) During the early phase of the flight the dragon takes many deep breaths to oxygenate its blood and then holds its breath once it passes out of the range where it can breath. Whales can hold their breath for up to 90 minutes.

Once the dragon is high enough or the balloon/kelp pops it drops down in a very stream lined shape with its wings folded back. It is still holding its breath. Here it will break the sound barrier. The pray it is falling on will not see or hear it coming. The pray is going to have to give it a huge amount of energy. This has to feed a dragon after all.

As the dragon needs to slow down it first goes from noes down to nose level then slowly expands its wings. Hopefully managing to glide out of the fall before it splatters its self into the ground.

The highly flammable plants may be a problem with this plan. Maybe need to explain that the plants seeds can be activated by fire and thus why they are around fire breathing dragons. We are trying to deal with big dragons, some amount of hand waving is required to deal with the square/cubed law.
Well, the big problem here is air resistance. Falling objects top out at a speed of somewhat above 500 km/h because of air resistance. Sound of speed is 1200 km/h. So it would need immense energy to speed up above that limit. Luckily there is an easy way around it: just decrease the air pressure. To get still enough oxygen to support big creatures the percentage of oxygen in the atmosphere has to be increased. But all that are possibilities and would it make easier to achieve higher speeds. Still, [most birds reach their highest velocity in dives](http://en.wikipedia.org/wiki/List_of_birds_by_flight_speed), so you may want to let the dragon break to supersonic speeds while make an diving attack from a higher flight position.