made its newspaper debut on February 17, 1958, and was among the longest-running strips still written and drawn by its original creator when Hart died at his drawing board in Nineveh, New York, on April 7, 2007.

by gag writers Jack Caprio and Dick Boland (who later joined Hart and cartoonist Brant Parker on The Wizard of Id).

The animal characters include dinosaurs, ants and an anteater, clams, a snake, a turtle and bird duo, and an apteryx (presented in the strip as being the sole surviving specimen, and hence self-aware of its being doomed to extinction).

Background detail is often limited to a simple horizon line broken up by the occasional silhouettes of a stray volcano or cloud.

"Retail stores", "shop counters", and "businesses" are symbolized by a single boulder, labeled (for instance): "Wheel Repair", "Advice Column", "Psychiatrist", etc.

Other characters attempt to harness fire or to discover an unexplored territory, like Peter trying to find the "new world" by crossing the ocean on a raft.

As time went on, the strip began to mine humor from having the characters make explicit references to modern-day current events, inventions, and celebrities.

Increasingly familiar visual devices, like the makeshift "telephone" built into a tree trunk, also started to blur the comic's supposed prehistoric setting and make it rife with intentional anachronisms.

"The art style, like that of Charles Schulz's Peanuts, masks sophisticated minimalism with a casually scratchy veneer," according to comics historian Don Markstein.

One such periodic recurring gag has Peter communicating with an unseen pen-pal on the other side of the ocean, writing a message on a slab of rock that he floats off into the horizon.

daily strip from December 7, 2006, attracted criticism for defining infamy as "a word seldom used after Toyota sales topped 2 million."

The day was the 65th anniversary of the Japanese military's attack on Pearl Harbor, and the punchline of the strip refers to Franklin D. Roosevelt's "Infamy Speech" which requested from Congress a declaration of war against Japan.

References to Christianity, anachronistic given the strip's supposed setting and the implications of its title, became increasingly frequent during Hart's later years.

strips were pulled from comics pages on several occasions due to editorial perception of religious favoritism or overt proselytizing.

The American Jewish Committee termed the Easter 2001 strip, which depicted the last words of Jesus Christ and a menorah transforming into a cross, "religiously offensive" and "shameful",[22] and accused Hart of promoting supersessionist theology.

[23] A 2003 strip depicting a character using an outhouse with a crescent symbol on the front, slamming the door shut, and declaring, "Is it just me, or does it stink in here?"

Open in 2006 was disrupted by flooding, prompting a change of venue to the Turning Stone Resort & Casino in central New York state).

Jim Davis, Mike Peters, Mort Walker, Paul Szep, Dik Browne, John Cullen Murphy, Dean Young, Stan Drake, Brant Parker, Lynn Johnston, and entertainer Tom Smothers would put on a free show for the community, drawing and signing autographs for golf and cartooning fans.