Getting into a bar fight is so easy, a caveman could do it!

Two security guards who spend their days protecting the dinosaur bones and Neanderthal mannequins at the American Museum of Natural History were busted after a bloody brawl with other guards at an Upper East Side tavern, sources said.

The trouble began when museum guards William Vera and Michelle Castro allegedly got into a scrap while off at the Jake’s Dilemma bar at 430 Amsterdam Ave. at 11:10 p.m. Friday.

When two other guards tried to break it up, Vera allegedly choked one and stabbed another in the wrist.