The book gives the flying reptile the following:
8 speed
7 strength
5 brains
8 attack
4 defense
It gives the bird this:
8 speed
5 strength
6 brains
6 attack
2 defense
It says the reptile wins like this
"Although they are both strong fliers, once on the ground, Quetzalcoatlus's four-point stance allows it to overpower and outflank the Ancient Giant Condor"