'An American Werewolf in London' star: Decapitation comes with jokes nowadays

They just don't make werewolf movies like they used to.

Actor and filmmaker Griffin Dunne, who starred as Jack Goodman in the 1981 horror classic "An American Werewolf in London," spoke to FOX411 about the film's groundbreaking use of horror mixed with humor.

"Critics were almost hostile that a horror movie would dare to mix a different tone of humor with a horror film," Dunne said. "Now it’s just standard fare, you can’t chop somebody’s head off without someone making a macabre sort of joke about it."

Dunne says he's surprised the film has achieved cult status, especially since it had such a "tepid reaction" when first released.

WATCH: Full interview with Griffin Dunne

The actor admits he isn't a big horror movie buff, but does love history -- a hobby that came in handy in his latest role as history professor Lewis Birch in "The Discoverers." The indie flick follows Lewis and the Birch family as they search for Lewis' missing father.

"My two teenage kids, who I’m pretty discontent with, the three of us end up having to follow him on this re-enactment of the Lewis and Clark trail in order for me to get to Oregon where I’m supposed to deliver a speech," Dunne said. "Lots of self discovery."

Along the way, Dunne learned some interesting facts about Meriwether Lewis and William Clark.

"I didn’t know that the real Meriwether Lewis was actually what would now be called bipolar; a severely depressed man who tragically killed himself," Dunne said. "They don’t teach you that in school."