LOS ANGELES — When Steven Spielberg brought home early footage of a stop-motion dinosaur from his new movie Jurassic Park, his kids' reaction couldn't have been more promising. They loved it.

But Spielberg was unmoved; it wasn't quite right.

That twinge of dissatisfaction, deep into pre-production stages, derailed months of painstaking planning. It also hatched a whole new species of visual effects, a breed that will be on display tenfold in Jurassic World.

SEE ALSO: 'Jurassic World' review: Leave the kids at home. It gets gnarly.

Though Spielberg's digital dinos were a first for the medium, designed on the fly in those heady pre-visualization days, they were so realistic, so present and expertly rendered, that watching them today is every bit as breathtaking as it was in 1993. Computing advancements have made CGI infinitely more doable, but those creatures looked quite right from the getgo, and still do.

We started at stop-motion, now we here

Spielberg assembled the Mount Rushmore of VFX — Stan Winston, Phil Tippett, Dennis Muren and Michael Lantieri — to bring dinosaurs to life for Universal Pictures' adaptation of Michael Crichton's book. The plan was to incorporate a blend of conventional techniques: full-scale mechanical dinos (like the T-rex at the paddock and the ailing triceratops) and high-speed miniatures (the running herds, many of the raptor shots).

The massive animatronic T-rex from "Jurassic Park."

Tippett over the years had developed a technique called "go motion," which adds the motion blur required to make his models appear to be moving smoothly through the frame. A version powered the AT-AT walkers and Tauntauns in The Empire Strikes Back, but he was ramping up a far more ambitious task for Jurassic Park.

The first test went well.

"My kids bought it. They said 'Wow dad, a real dinosaur!'" Spielberg said in the 1995 video The Making of Jurassic Park. "The movement was very accurate, very rhythmical, but there was something a bit go-motion-ey about it."

Spielberg wanted another way.

At the time, Industrial Light and Magic was experimenting with computer-generated graphics, which it had used in the James Cameron films The Abyss and Terminator 2: Judgment Day. But CGI had only been used to make stylized liquid and metallic surfaces, not living, breathing creatures. Muren, who had been working with the technique at the Bay Area effects shop, suggested they give it a try, and created a short shot of T-rex running through a field.

Tippett immediately saw the writing on the screen.

Phil Tippett at Comic-Con in 2007. Image: Dan Steinberg

"I'd been working really hard doing these animatics, with stop-motion animation," Tippett told Mashable. "When we first took [the new footage] down there and showed it to Steven... I knew that was it."

"I've become extinct!" Tippett famously exclaimed, a line Spielberg liked so much he wrote it into an exchange between Drs. Alan Grant and Ian Malcolm.

"I thought my life was over," he told Mashable, adding that he immediately got sick with pneumonia and, forced away from the set, doubted he'd return.

But Tippett had learned an extraordinary amount about paleontology, the physicality of dinosaurs and the movements of animals for Jurassic Park and his previous dinosaur short films. Though the creatures' bodies were being moved from his fingertips to computer screens, Tippett knew how they were supposed to look and behave. He had a new role: dinosaur supervisor.

"On the page, Crichton could have the T-rex pick up the car, but a Tyrannosaurus could never do that," Tippett said. "Steven's edict was that he wanted to play them not as monsters but as animals. So that just required a great deal of figuring out mass, weight and behavior."

Leaps and bounds of faith

With a proof-of-concept footage still cooling, the production rolled with brisk shoots in Hawaii and California between August and November 1992.

That included a shoot in the rain with Winston's full-sized animatronic T-rex, the one that would threaten the kids and snack on a lawyer. The 17,500-pound dino stood 20 feet high and was 40 feet long, and though its in-camera presence brought a certain immediacy to those scenes, there's no way today's filmmakers would go to the trouble — that would be CGI, too.

The OG T. rex doing her thing in "Jurassic Park." Image: Rex Features via AP Images/Associated Press

Avengers: Age of Ultron director Joss Whedon told Mashable earlier this year that animation has come so far that for many shots, you don't need any in-camera footage at all.

"We could go in without anything," he said. "Their ability to sort of bob and weave when we didn't have the reference or when we changed our minds about what we did and didn't want in there — it's just sort of dazzling. There's not so much industrial light as there is magic up there."

But the Jurassic Park crew didn't have that luxury, shooting several scenes in which the actors had to pretend that they were reacting to dinosaurs that Spielberg's VFX team would add later. Whatever they got during those hasty shoots, they would have to work with.

Shooting actors without dinos was a leap of faith for the "Jurassic Park" crew.

And they were learning quickly.

"We were almost scared to be too experimental at the beginning of the learning curve," Spielberg said. "But after a while, we were shooting this thing like we had been doing CGI movies for 10 years."

A scene from "Jurassic Park" — this one with a digital dino added in.

His confidence was so high that upon realizing the T-rex was the movie's biggest star, Spielberg rewrote the end of the film to include her. But the animatronic version wouldn't even make an appearance in the climax; she was ready for her close-up on the computers alone.

Shooting wrapped nearly two weeks ahead of schedule, but there were still six months of critical post-production. Spielberg locked his print before a single CGI dino was added and headed overseas to start shooting Schindler's List.

Post-production

The computer software used for "Jurassic Park" looks downright quaint today.

Three rooms at Industrial Light and Magic housed countless dozens of servers that would power Jurassic Park's post-production push. They were noisy, they were hot and they were cranky, but they had just enough computing power for ILM's team to design and render dinosaurs to Spielberg's satisfaction.

Much of the painstaking work was done on computer screens with fonts and operating systems we'd find downright quaint today. Artists largely used keyboards to do their work.

Though Tippett's lifelike models were gone, they soon learned that making mechanical dinos that would send reference points into the computers as they were manipulated by hand could significantly increase their ability to animate them — something of a precursor to the ball-suits we see in today's CGI filmmaking.

A model used to manipulate the computer-generated dinos of "Jurassic Park."

Though today's studio marketing would be falling all over itself to tout these groundbreaking techniques, Spielberg insisted that it all get wrapped up on the down-low.

"Steven didn't tip the hand," Tippett said. "He wanted to keep it magical. He didn't let the CG out until theatrical release. He didn't want to go down that path; he wanted the cinematic experience to be pure."

Steven Spielberg on the "Jurassic Park" set in 1993. Image: Murray Close/Getty Images

The result was one of those films: anyone who saw it in theaters remembers the experience. We'd seen dinosaurs onscreen before, from the 1933 classic King Kong on down, but nothing naturalistic enough that 22 years later, it still looks... real.

That experience convinced an entire generation of filmmakers that their visions, no matter how impossible, could be realized. George Lucas, seeing what his own company was capable of, began to think again about Star Wars. Peter Jackson rediscovered his love for fantasy films, which could now take on a whole new scope and scale.

It was a genesis moment in film history that has led us to this weekend's Jurassic World, a state-of-the-art CGI-fest whose dinosaurs are bigger, meaner, and far more numerous.

But no more naturalistic or awe-inspiring than their earliest ancestors.

Have something to say about this story? Share it in the comments.