In November 1960, LIFE magazine published an article about the breakout success of Hanna-Barbera’s seminal primetime animated series The Flintstones. The piece featured three photos of the studio, but what they didn’t publish is even more amazing. Photographer Allan Grant took 850 photographs for the magazine assignment, documenting every part of the studio’s operations. Remarkably, all of those photos are now available to view online in the LIFE Photo Collection.

Grant chose about twenty scenes to document, so there are dozens of slightly-varied photos of the same people and scenarios. Nevertheless, the images offer a revealing look at Hanna-Barbera just before it became the largest animation outfit in the world. It’s positively refreshing to see the two bosses—Bill Hanna and Joe Barbera—assuming such hands-on roles in their productions. Hanna and Barbera understood every step of the animation process inside-out, thanks to nearly two decades of creating Tom & Jerry theatrical shorts at MGM, and during the early years of their own company, they were deeply involved to ensure a consistent final product. These photos are a tribute to their professionalism and expertise in creating memorable animated characters that are still beloved by audiences half a century later.

Here are some of the highlights from the LIFE collection. Click on any image to enlarge: