As reviews flood in for the new Teenage Mutant Ninja Turtles movie, it seems like the origin stories for most of the beloved characters have been altered and classic fans are outraged. But which characters got the cut and where did they decide to draw from?

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ScreenRant outlines the origin story on Friday and found that most of the material would be drawing from recent inspirations of the turtles rather than the classic comic book series and television shows.

In the new film, the origin of the ooze that mutates the turtles is left open for exploration in future sequels. Yet, Eric Sachs (William Fichtner) outright states that the substance is extraterrestrial, which shouldn't come as a complete surprise to anyone who caught the T.C.R.I. label on the mutagen's canister. In the comics, T.C.R.I. (the Techno Cosmic Research Institute) is actually a shell corporation/Earth base for the alien species known as the Utroms - the same life forms as fan-favorite baddie, Krang.

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As for Megan Fox's version of April O'Neil, the film decides to dive into a backstory with her father being a doctor who worked with Sachs on the ooze. According to ScreenRant, this father character is a supporting character in the most recent 2012 animated series. In that version, Dr. Kirby O'Neil works as a psychologist, not a geneticist, but his abduction by The Kraang (the 2012 iteration of the Utroms) is still the inciting event that first brings April and the turtles together.

One of the problems fans have had with the movie is the lack of origins for the turtles' master Splinter and the villain Shredder. There were reports that the turtles' origins would come from an alien story, but the movie seems to align with the source material well.

According to ScreenRant, the biggest departure in the new film is Master Splinter's backstory, which, in most versions of the mythology, has been directly tied to the rise of Shredder. In the original comic book series, Splinter was the pet rat of a benevolent ninja, Hamato Yoshi, who fled Japan - only to be hunted down and killed by rival warrior, Oroku Saki (aka The Shredder).

Teenage Mutant Ninja Turtles is now in theaters.

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