Rexy

Origins
Jurassic Park director Steven Speilberg wanted to have full-sized animatronic dinosaurs for the film due to having been impressed by the Universal Studios theme park attraction. Most notably, Speilberg wanted a full-sized walking Tyrannosaurus. The King Kong attraction and the company, who created museum exhibits, were observed. Talks were also made with the, but the most serious discussions were with Bob Gurr, who had designed the King Kong Encounter. Gurr had a planned design for the animatronic. Micheal Lanteri recalls that Gurr's plan for the mechanical T. rex would have been high-tech, being completely balanced and operated by motion sensors. Every time it would start to take a step the motion sensors would detect the center of gravity going over and would adjust its balance with its tail. However, the special effects team became discouraged over the possibility of a full sized walking T. rex after consulting researchers from, the , and the , discovering how much work went into getting these robots to move. Soon, Speilberg realized the difficulties of a full-sized walking animatronic, to his disappointment.

But Speilberg still wanted full-sized dinosaurs in the film, albeit being possible by more conventional means. Stan Winston Studio was key among the potential candidates to bring Speilberg's vision to life. Before Jurassic Park was even greenlit, Stan Winston pulled artist Mark "Crash" McCreery from all of his other assignments to create drawing of the T. rex to get Universal Studios and Amblin Entertainment interested in the film. The resulting drawings gained the reception Winston wanted, and after months of informal development Universal entered into a contractual agreement with Stan Winston Studio to create the dinosaurs of Jurassic Park.

Preparations for Rexy's attack on the Main Road was problematic for the filmmakers due to how the T. rex was to interact with the characters and physical props. Initially, as a budgetary decision, Stan Winston Studio was to create separate full-sized parts of her body to portray her. When the sleeping T. rex scene was still planned for the movie, Stan Winston Studio was to build a full-sized prop of the slumbering giant. A fifth-scale rod puppet was also considered for her portrayal. However, Stan Winston explained that this would have gone over-budget, meaning that many of these proposed portrayals of Rexy were scrapped. The full-sized animatronic that Stan Winston Studio would make was conceived when Stan Winston made a proposal to Steven Speilberg to create the sleeping T. rex a miniature rather than full size and to use the funds to a full-sized animatronic instead.

Full-sized mold
As a reference, Stan Winston Studio created a full-sized clay mold of the Tyrannosaurus. The armature was designed by Richard Landon as a triangular truss that ran through the length of the sculpture's body and up into the head and into the tail. To create parts of its body, a 1/5 scale maquette was cut into cross sections with each individual part numbered, then projected up five times onto a piece of plywood using an opaque projector before the plywood pieces were cut out-albeit by two inches to allow the Stan Winston crew to place the molding clay-and hooked onto the armature. When all the parts were attached to the armature, hardware cloth, fiberglass, and Roma clay were added in this order. Shane Mahan explained that the choice of Roma clay on all of the big sculptures made for the film was because it was oil-based.

The sculpture took sixteen weeks to complete with a team of eleven sculptures sculpted the life-sized Tyrannosaurus.These sculptures were: Mike Trcic, Joey Orosco, Mark Jurinko, Bill Basso, Robert Henderstein, Greg Fiegel, Len Burge, Christopher Swift, David Beneke, Richard Davison, and Shane Mahan. Tricic and Swift in particualr worked on the head and neck of the sclupture. Elevated platforms and scaffolding were built around the T. rex so the sculpters could reach the higher regions of its body.

Full-sized animatronic
During the design process of the full-sized animatronic, Bob Gurr was once again consulted and he provided the mechanical team with initial designs of the animatronic. Stan Winston wanted to approach the full-sized animatronic as a large, light-weight puppet until he was convinced by Evan Brainard that this choice would have been impractical. Electric motors were also considered but was later dropped as an idea due to the motors at the time were not powerful enough to run such a large machine, which led to hydraulics being used for the animatronic. Because the Stan Winston and his team were inexperienced in hydraulics, Winston hired Craig Barr, who was a veteran of theme park attractions that were hydraulically powered and computer controlled, such as the King Kong Encounter. Barr was given his first assignment upon being hired to train the Stan Winston Studio mechanical team in hydraulics. Barr would also hire several engineers experienced in hydraulics, these engineers being Lloyd Ball, Tim Nordella, who was one of the lead designers of the Universal Studios attraction the E.T. Adventure, and Steve MacIntyre of Anitech, a company that builds animation control systems. Overall, the full-size Rexy would be fully hydraulically powered save for its eyes, which were instead radio-controlled.

To actuate the animatronic in real time, Stan Winston conceived the idea to use a telemetry device in the shape of a miniature T. rex referred to as a "waldo". Winston has said he came up with the idea when visiting a robotic manufacturer that did a lot of work for Disneyland and DisneyWorld to talk to them about their hydraulic cylinders and actuating devices. During this visit, Winston said he put on one of their telemetry suits. Later that night, Winston claims to have dreamed the idea for the "waldo". The "waldo" was essentially a miniature armature of the T. rex made of aluminum with forty axes of motion that could be actuated manually and translated directly to the full-sized animatronic. Operation of the "waldo" required four puppeteers who controlled by four handles located on the front of the head, the tip of the tail, and two in the middle for the motion base that the animatronic was mounted on, allowing the animatronic to move in real time. The waldo was also capable of recording movements made to it so that pre-recorded movements could be replayed at the press of a button.

Craig Caton was responsible for the idea to use a motion platform for gross body movements. Stan Winston liked this idea so much that he immediately went to tell Steven Speilberg, which led to an agreement to be reached between Universal Studios and Stan Winston Studio to split the costs of such an expensive piece of machinery. Winston contracted McFadden Systems, a company known for creating flight simulators, to create much of the basic platform construction of the specifically made "dino-simulator" to mount the T. rex on. McFadden member Larry Hayashigawa joined as a consultant as well.

The animatronic's skeleton was made of steel per suggestion from master welder Armando González. The mechanical team had many discussions on what to use with aluminum being considered and the idea of composites made of fiberglass and carbon fiber sections was entertained by the team. Alan Scott designed the neck and tail of the animatronic as a spiral so that they would expand and contract while never losing its shape. Scott came up with this design while working on the practical effects of the raptors, which utilized this same trait.

Insert head and legs
The insert legs were designed by Richard Landon. Used in low angle shots, the insert legs not only consisted of the legs of Rexy as well as her tail and part of her underbelly.

The insert head consisted of Rexy's upper body. Featuring an extra extending tongue and a dilating eye by Jon Dawe, this animatronic had more detailing as well as added mechanics for the close up shots it was intended for.

Misc
It is popularly believed that the scene where Rexy pushes her head through the top window of the tour vehicle Tim and Lex was unintentional. However, storyboards exist of this scene proving this notion to be false.

Notes and references
