Attacks of opportunity against Colossal (long) creatures turning back Question

[Memphos]

Hello adventurers, I came here to ask for your wisdom and knowledge.
Yesterday I had 3,5 D&D session. At the end of it, my team (I'm not the master) asked out DM to let us confront "in the dreamworld" (we already tried but died) a triceratop, to see if we had improven. We are a gestal party, but that's not the question. In some book or on some official website, I remember to have read something on the matter, but I could be wrong. Our opponent was a standard triceratop. I attacked his back, while my team mates were attacking it on front. Because I got a crit, I could have sliced his tail, but the DM didn't say anything about. Therefore, the triceratop turned back to attack me, giving attacks of opportunity to my mates. Now, the question: being such triceratop a Colossal Creature (long), in his turning back, do I get attack of opportunity, because its massive body takes a while in turning back, or don't? I am sure to have read something about opponent bigger than you, but I'm not sure.:smallredface:

[Marnath]

Hello adventurers, I came here to ask for your wisdom and knowledge.
Yesterday I had 3,5 D&D session. At the end of it, my team (I'm not the master) asked out DM to let us confront "in the dreamworld" (we already tried but died) a triceratop, to see if we had improven. We are a gestal party, but that's not the question. In some book or on some official website, I remember to have read something on the matter, but I could be wrong. Our opponent was a standard triceratop. I attacked his back, while my team mates were attacking it on front. Because I got a crit, I could have sliced his tail, but the DM didn't say anything about. Therefore, the triceratop turned back to attack me, giving attacks of opportunity to my mates. Now, the question: being such triceratop a Colossal Creature (long), in his turning back, do I get attack of opportunity, because its massive body takes a while in turning back, or don't? I am sure to have read something about opponent bigger than you, but I'm not sure.:smallredface:

I don't think so. Unless your group uses the facing rules (Unearthed Arcana I think?) the assumption is that you are facing whichever way is most beneficial to you.

[Malroth]

Step 1) Cast Ray of Stupidity

Step 2) ????

Step 3) Win instantly

Step 2 can be any non suicidal action since you already won using step 1.

[Memphos]

Heh, we don't have that, but i'll:smalltongue: make a note of it

Besides, we actually managed to beat it, somehow, thanks to my critical dealt with a greataxe. And i'm a Goliath Barbarian/Dread Necromancer

[TuggyNE]

Triceratops is Huge, not Colossal. But Marnath is right; facing rules don't exist by default, and there are no AoOs for a creature moving around within its space.