How do you get t-rex in fossil fighters?

Answer 1

go to parchment desert talk to the guy and you go back to the guild and get today special oasis seed for 20,000 g do that four times and then go to the fourth oasis and there will be t-rex, but it is very hard to find. just keep looking until you get it

Answer 2

beat thegame, talk 2 the old guy in parchment desert.go 2 shon n' buy an oasis seed. give it 2 him. repeat 3 more times. then it wil take about like 70-100 times 2 get his head

also, you can use Guan (mt. lavaflow) get all Guans parts and he transforms into a complete T-rex. it takes 360 fp though, so wait until you are strong enough to wait for all that fp.

and just before you go to knotwood you can buy his head