"T" is for "Thornhopper"

Thornhopper

No. Enc.:  0 (2d6)
Alignment:  Neutral
Movement:  180' (60')
Armor Class:  4
Hit Dice:  6
Attacks:  1 (gore or kick)
Damage:  2d8 or 2d6
Save:  L3
Morale:  8
Hoard Class:  None
XP:  1,070

Thornhoppers are armored, flightless insects of bison-like proportions that reach lengths of 15' long. Domesticated over the post-apocalyptic centuries, thornhoppers can carry two riders and up to 500 lbs of extra gear.

Thornhoppers often Trample when provoked, or at their riders' insistence.  And they are nigh-invisible in verdant environs, Surprising (even if carrying riders) on 1-5 on 1d6.

Mutations:  Increased Balance