Character animation was a challenge for the animation team. The animation director studied a prairie dog zoo exhibit to get right size and fur.

In terms of the character animation, which was mostly keyframed, there were lots of challenges for Animation Director Steve Rawlins (Harry Potter and the Order of the Phoenix, Star Wars: Episode I & II). "This was a small animation show by usual standards," Rawlins admits,"but it eventually grew to more than we anticipated. It began with the prairie dogs, which were the first things out of the gate. That was fun to do, especially the iconic opening [poking fun of the Paramount logo].We ended up doing some early animation, which we sent to Steven for approval. I actually went to the zoo in San Francisco and studied the prairie dog exhibit. The issue that came up was the look of the prairie dog in terms of the size and shape of the fur. The interesting thing at the zoo is that they're all different, with the older ones tending to be fatter. So we had to pick one and floated somewhere in the middle. As far as animation is concerned, we went for the upright, standing at attention pose."

At the end of the Doom Town blast, when Indy is hurled in a fridge, there was a bit more CG reliance than envisioned. "Where [the flying fridge] comes to a stop they ran a rigid simulation and intended on matching it with the real one with Indy coming out. But they wound up using the CG one because it was easier."

However, the monkeys represented the most labor-intensive challenge. In addition to requiring multiple monkeys (ranging from 25-50), they had them interacting with vines in the jungle or actors on the vehicles. "They were fast moving and the volume was large for a lot of the time. They had a system in place where there were separate assets for the monkeys and vines and they could get as many assets as they wanted. But for the vines and monkey tails they borrowed the tentacle tool from The Pirates of the Caribbean: Dead Man's Chest. It was written as a way of rigging quickly and flexibly, so instead of the creature set-up department having to rig the vines and tails with a certain number of controllers, they could do it on the fly and then choose the number of controllers necessary for a given moment.

"Another thing we did as well was run simulations on some of the tails, where the creature set-up guys used quick Maya soft simulation techniques, allowing the animators to run fast, almost realtime sims. This came in handy for the wide shots of the monkeys zipping by."

By the way, the monkeys were of the Capuchin variety, the same species used in Pirates of the Caribbean and Raiders of the Lost Ark.

Interestingly, Spielberg wanted the monkeys swinging on vines; however, in looking at reference and speaking to the animal trainer, Rawlins discovered that's not what they do in the wild. "They jump from branch to branch. The initial animatics contained different breeds of monkeys and a variety of motions, but Steven still preferred them swinging, so it ended up being about 60% swinging and 40% jumping from branch to branch. What we found that made it more difficult is that often when you do a CG-intensive character such as Davy Jones, there is a large amount of development work that goes into getting a character of that level working, and that investment of time and resources pays off over the course of hundreds of shots. But Indy was full of one-offs and the hard part was that they put a lot of effort into it yet there wasn't the time to refine the work. With the monkeys, there also weren't enough of them to run a crowd simulation, so they all had to be keyframed. Shots were swapped back and forth or bridged as needed.

"For monkeys on the vehicles, the layout department had to provide really tight matchimations of each of the characters using digital doubles and paint and rotoscoping work for the action. In fact, in the main shot where the monkey runs over Spalko's face, we put a couple of monkeys in the back as a contrast to all the hyper-activity.

"For the ants, [which numbered in the hundreds of thousands] we used our own [Zeno-based] crowd simulation for the most part, with animation providing simple cycles and hero animation for key moments. This was the first time they used the new crowd system and it was much quicker and able to handle larger volumes than the previous Maya-based system. For shots where they start pouring over the car, there were a few custom hero ones placed here and there to break up the line so it wouldn't look too perfect."