I'm not in the engineering core but I'm a good researcher hear what I found.

Rancor
Natural Range:
    Dathomir: forest?
Niche:
    predatory carnivore.

Rancors are huge, voracious, long-armed predators which roam the forests of the remote and little-known planet Dathomir. They are also found on dozens of other worlds. The leathery brown hide is thick enough to allow a rancor to shrug off hits from hand-held blasters. Their maws are full of sharp, triangular teeth which are primarily used for gripping and rending prey; a rancor does very little chewing, preferring to swallow food in large chunks. The specimen owned by Jabba the Hutt was a juvenile in poor health, standing at only five metres tall. Wild rancors grow to greater dimensions.

On Dathomir local Force-sensitive witches use rancors as tame mounts. Although Jabba's rancor is clearly non-sapient, at least some of the rancors of Dathomir seem to approach intelligence. These rancors are social creatures, hunting in family-based packs.

It is not clear whether this is the natural state of the rancors, or whether they are have been altered by Force-based sorcery. The notion that rancors may be artificial or modified life-forms finds support in the fact that Emperor Palpatine kept an army of vicious sub-intelligent rancors at his Citadel on the Deep-Core resort world of Byss. These rancors were referred to as "crysalis beasts" and seemed to be among the menagerie of monsters deliberately created in experiments with the Dark Side of the Force carried out by Palpatine and his adepts. It seems possible that rancors might be one of the standard monstrousities available for creation via the ancient arts of the Sith. Indeed the Sith were infamous for the creation of abominations of nature, as seen in Dark Lords of the Sith, The Sith War and The Jedi Academy Trilogy.

http://www.theforce.net/swtc/zoology/rancor.html

Well thats a little that I found id love to do some more research for you.
 
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LCRW JSRussell/Kaph-7/Pheonix Wing/mSSD Atrus/DEF/VEN/VE

Rancors were five to ten meter tall monsters which originated on the planet of Dathomir. Although found on other worlds such as Ottethan and Rakata Prime (where they were brought on crashed starships), those from Dathomir were said to be stronger and more intelligent than others, and could be domesticated although with difficulty.

Rancors walked on two small, stubby legs, with abnormally long arms for catching prey. A rancor's flat face was dominated by a large mouth full of razor sharp teeth. The skin of a rancor was tough enough to deflect blaster bolts, making it an efficient killing machine. Jabba the Hutt kept one as a pet in a pit beneath his palace courts, dropping victims in to feed it.

While stranded on Taris, the reformed Revan had to get past a rancor in order to infiltrate the Black Vulkar base.

Though rancors were usually considered unintelligent beasts, the rancors of Dathomir appeared to be sentient, caring beasts mourned their family members who die. These rancors were used as mounts by the Witches of Dathomir. The reborn Emperor Palpatine also kept several alchemically altered Chrysalide rancors at his Citadel on Byss. Imperial Scientists also worked on a mutant rancor, twice as big and strong as a normal rancor. Also, would spew out toxic fumes that would kill a human instantly.

http://starwars.wikicities.com/wiki/Rancor
 
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Corporal Yillis
Iron Horse Squad

TRP/CPL Yillis/1SQD/1PLT/1COM/1RGT/1BAT/VEA/VE/Tadath [LoR] [WM] [GS]
Rep/GameRep Yillis/GameRep: 6/Gaming Division/VET /VE