Can't go back through checkered room

[kkkkkrrrrr]

I'm totally stuck at the puzzle at the end of level 9. At first I hadn't a clue at all myself how to solve it but that's could be because english isn't my mothers tongue, I'll buy that. But now I've checked a walkthrough and seen that i have all the items needed except the skull. How the hell I was supposed to know it was gonna be useful is another question. I do however remember seeing one at the beginning of level 8. Just return then, right? Hah. If it was that simple.

Okay, so my problem is this. I have to go back but it is impossible. There are several dinosaurs in that stupid checkered room and they, of course, keep closing the gate. I can't kill them through it because I don't have enough arrows or throwing things. Trying to walk back and forth so that they move just causes another dinosaur behind me to come and attack me and I die. I have closed all doors behind me so they must be spawning there too. This is starting to become ridiculous. The game was good until that puzzle. I'm not getting anywhere and am gonna give up if nobody knows a solution to my problem.

[Dr.Disaster]

The Ice Lizards are spawned in a rather small area: past the door with the "Trespasseres will be hunted down" wall text and the Outer Sanctum. Since you got several inside the Checkered Room you did not close the door to their area upon trespassing so they could expand into the level.

Now before trying to get past the Checkered Room you now need to
1) close the door at the "Trespasseres will be hunted down" wall text and
2) clear all Lizards between that door and the Checkered room, including the Armory branch.
Otherwise you are always at risk of being ambushed.

[Komag]

The spawning of the lizards only happens when you step on two specific squares, on by the front door, and one near the Outer Sanctum door. There is a timer of around 5 minutes before they can spawn again. One of the squares only spawns one, the other spawns two. So if you clear the all out you should be fine, then camp a little ways away from the checkered room (such as in the armory) and then go back and check and hopefully they have moved on.