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: 
Taking the speed of a perigrine falcon as 1/3rd the speed of sound.

We know that the force of acceleration is proportional to mass.

We know that the force opposing this (air resistance) is proportional to surface area and the square of velocity.

We can rearrange those to say that velocity is proportional to SQRT(mass/surface area).

We can say that mass is proportional to density and wingspan^3.

We can say that surface area is proportional to wingspan^2.

So velocity =k x SQRT(density x wingspan).

We can define density to be density(any animal) = density(peregrine falcon) x y.

using symbols v = p(falcon) x y.

Where y is the density of the animal divided by density of a falcon.

So v = k x SQRT(pyw).

For a peregrine falcon, v = 1/3 speed of sound = 113 m/s. Where; p=1,w =1.

113 = k x SQRT(1).

So k = 1.

For a dragon:

v = 113 SQRT(xw).

Lets set w = 30 meters, and density double that of a falcon, x=2.

v = 113 SQRT(60) = 875 = nearly triple that of sound.

Assuming you have solved the problem of how such a big and heavy animal flies, then getting them to dive much faster than sound is trivial.

The bigger they are, the faster they fall.
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.