Beware the dragonasaurus

The dragonasaurus is strong and tough
with a booming voice that’s loud and gruff.
All over its body are scales of green,
its huge yellow eyes are the meanest you’ve seen.
Of the dragonasaurus you’d better beware,
for when it growls hot flames fill the air.
Nevertheless, they’re good natured souls
provided, of course, you do as you’re told!