The original Jurassic Park film revolutionized not only the special effects and film worlds, but the public’s understanding of dinosaur behavior and evolution. When it first released two decades ago, The New York Times even called the film “seductively scientific,” but do those same words hold up today? Not quite; just as special effects have evolved since 1993, so has science. What, exactly, have scientists learned in the past 22 years? Quite a lot, it turns out.

Back in 1993, Jurassic Park walked a fine line between fact and fiction when it came to the depiction of dinosaurs. On one hand, the film was very much ahead of the game, as the idea of birds descending from dinosaurs was still fairly contentious in the 1990s. On the other hand, Spielberg did take some artistic license—exaggerating, for example, the size of Triceratops “droppings.”

According to paleontologist Luis Chiappe with the Natural History Museum at Los Angeles, the evidence backing the bird–dinosaur descent theory was based entirely on bone structure at the time of the film’s release. As a result, the theory was still controversial. Dr. Grant’s character only fueled the debate when audiences first heard him say, “I bet you’ll never look at birds the same way again.” Since then, hard evidence of a dinosaur–bird relationship has only continued to evolve—and, despite the prevalence of lizard-like dinosaurs in the media, the dinosaur–bird theory is now widely accepted by scientists.

Meanwhile, another of the film’s theories has lost traction, with the conclusion that DNA extraction from mosquitos encased in amber is far fetched at best. Scientists have tried again and again to extract DNA from dinosaur bones to no avail, correlating a 2012 study that placed the half-life of DNA at just 521 years—far from the 6.8 million years since dinosaurs.

In fact, if Jurassic Park were written today, there’s a strong chance it wouldn’t use bugs in amber as a plot device, but instead the reverse engineering of chickens. Scientists Jack Horner and Hans Larsson have been working together on such a process for years, primarily using a technique called “atavism activation.” Atavisms are ancestral characteristics that remain hidden in DNA and can be unlocked, theoretically, to create what Horner affectionately terms a Chickenosaurus—or a bird that more resembles its ancestors.

A more modern franchise might also feature dinosaurs with feathers rather than scales—and a T. rex we might hardly recognize. Fans of the speedy Tyrannosaurus who aggressively hunts her prey might be disappointed to learn that the real animals were quite slow—and probably not hunters either. In 1995, James Farlow concluded that the T. rex’s thigh bone could not have been strong enough for high-speed running, and a study from 2002 found that a T. rex’s leg muscles would have had to make up 86% of its body mass in order for the animal to run 45 miles per hour.

Interestingly enough, although John Hammond boasts in the film that they “clocked the T. rex at 32 miles an hour,” computer modeling puts its top speed during the famous Jeep chase at only 10-15 miles per hour (a much more realistic speed for Tyrannosauruses).

The same scene also portrays the T. rex as a seasoned hunter, which might not be true either. Its anatomy just doesn’t scream “predator,” according to expert Jack Horner, who cites the animal’s large head, enormous teeth, and comically small forearms as evidence. While Horner had already begun questioning this portrayal at the time of the film’s release, he has since coauthored a 12-year study that found Tyrannosauruses outnumbered their supposed prey—more evidence, for him, that they scavenged for food instead of hunting.

The fact that many of these inaccuracies have gone unchecked in the franchise’s sequels (including this summer’s Jurassic World) is sure to cause a collective groan of frustration from paleontologists. Yet many would probably agree that the franchise has done more good than harm by continuing to spark debate and renewing public interest in their field—and, if not, there’s always the Chickenosaurus to look forward to.

Maddie Stearn writes about stock footage, dinosaur science, and film for VideoBlocks.

Image: Universal Pictures