Get some 3-4 scorpions ( easily found in south zone 3). Pump every level into melee and health( mostly health). Now find a good level rex( commonly found in south zomes 2 and 3). Attack it but you have to be careful about it running away as scorpions are kind of slow. When it's knocked out feed it prime meat.

You've got a rex.

Dinoshark.

Last tip was on spino...