If Melanthios has time, he’ll try to hide.

Stealth: 14

It looks safe :)

Poole steps forward (3) and gets a few steps in when she realizes the floor is about to give. (acrobatics: 12) She manages a couple of quick steps to move to the side as the floor falls away down 20 feet. There seems to be a very narrow ledge on both sides that was supporting the floor and can be used to progress.

About 10x10 feet of the floor is gone, but the next piece seems to be solidly there.

Anyone wishing to follow Poole would need to succeed on a DC10 Dex(Acrobatics) check to balance on the ledge.

Poole ties a knot around her small hammer with her rope, and then tosses the hammer underhanded across the pit, telling each person who crosses to loop the hammer-and-rope through their belt as a backup in case they lose their footing, and they have a lifeline. She'll look for something on the other side to loop the other length of rope around to provide some block and tackling.

If I've misread this, and Poole hasn't crossed yet, she'll just tie one length of rope around her belt, hand the rope to someone, and dart across. Acrobatics: 18

Aurok crosses. 
Acrobatics 18 

Melanthios takes the rope from whoever gives it to him, and attempts to cross: 14

As Poole throws the rope back over and looks around for something to tie it to she notices the walls having niches in them, two on both sides over the next 10 feet of the tunnel. After that there seems to be about a 7 foot high wall or ledge or something and she can't see beyond it.

The niches however contain tall, rusty, but still very sharp blades that are positioned to swing out. It's safe to assume that this is a trap of sorts.

Aurok and Melanthios make their way over there easily enough. The space is now properly crowded between the pit and the niches on both walls.

Map (the brown diamonds are Poole, Aurok and Melanthios). Others are on the other side of the pit trap at the moment.

Aurok will cast mage hand to try to test the traps, looking to see what sets them off precisely. First waving through the air, then across the floor.

Mage hand doesn't seem to trigger anything other than some spiderwebs to have holes in them now.

Aurok scratches his head. ”I don’t suppose any of you has a 10 foot pole handy...”

Melanthios shrugs.

"I could try shooting an arrow over there."

"Anyone see a crocodile for me to ride?" Pool says, looking around, down the pit, on the floor of the trapped area ahead, anything for a croc to surf. Assuming none, she takes a handful of ball bearings out (about 40) and casts them across the floor ahead of her, waiting for blades to sweep forward. 

Nothing seems to trigger those blades.

Int checks for all three: Melanthios 18, Aurok 4 and Poole 12

Poole and Aurok drop into a discussion about the possible mechanics of this contraption and conclude that it probably must be a living thing crossing this floor to trigger it.

“Someone could go grab a goblin?”

"Or an undead..." Anzir suggests as he eyes the approaching enemies.

Irma listens to this discussion and says, "You want us to ... apprehend a goblin or a zombie and have it walk forward into a trap? If that's our only option then we should just return to our canoes and continue upriver. Can't you disable that stuff or run through real fast or climb a wall or something?"

Could Aurok aim his acid stream such that it would hit both blades along one wall? And if so, would that make it safe to cross or would the other blades be long enough to hit anyone crossing still?

Not quite, the blades are in the niches that go vertically along the wall and into the ceiling. You can definitely destroy one with each casting of [Tooltip Not Found] though.

Let me know how many you wish to destroy.

Aurok is going to try to destroy 2, destroying them right at the base, so as to have the blades somewhat intact.

Aurok suddenly shoots acid towards the upper corner of one of the niches and after some sizzling and a lot of stench a large rusted blade first falls down with a loud *CLANK*. It starts to fall sideways out of the niche, but as it's about 20 feet long and the corridor is just 10 feet wide then it wedges itself into the niche in the opposite wall. It looks like it may have disabled that one.

Stepping a bit forward the two blades further back scythe through the room and return to their niches. Aurok repeats the same acidic destruction on the second set of blades.

Now walking through this area triggers some grinding noises from one side of the room as the wedged-in blades are trying to move but can't.

Next up is a 7-foot-high ledge, which is easy enough to climb. The tunnel continues into the statue and it seemingly safe. As you continue then you arrive in a larger chamber.

The floor of this dusty, 40-foot-high, 20-foot-wide chamber is littered with dinosaur bones. Webs stretch from the walls to a 30-foot-tall central pillar, coiled around which is a narrow stone staircase, its steps covered with dust. Carved into the pillar are reliefs of a man carrying a crocodile. The reliefs follow the stairs to the top of the pillar, on which sits a large, beautiful, ceramic jug.

Melanthios sighs.

"Yeah, that doesn’t look suspicious at all.  Any volunteers to touch the creepy out of place jug?"