Run over to the east side of the same area to find the Endless Court Gnar Tamer (Elite), located in Scarlet Gorge at 3855, 2724 on the lowest level of the cliffs. Once the quest updates to kill it, go ahead and do so. Then capture his Young Rock Chomper with the Control Rod and bring it back to Uriel.
To see the whole quest series at a glance, see The Saga of the Endless Guide .