The cassowary, a flightless bird capable (of running) 30 miles an hours and (equipped with) claws the size of dragger, (rank) among the world’s (most dangerous) birds.
why equipped is ok? it’s not parallel to capable !
capable + preposition
equipped + preposition
The main problem is that you didn’t notice rank being used for a singular noun. If you did, you would automatically know any maybe-errors were correct and rank was wrong.