Most popular in World War II, nose art fell out of fashion during the Cold War as top brass imposed stricter rules on what could, and could not, feature on the aircraft under their command. It was a radical shift from the 1940s, when a wide variety of pulp art, fangs, and pin-up girls proliferated on fighters and bombers.

The A-10 doesn't need nose art to look mean. A 30-millimeter cannon does that job well enough. But the Warthog is a rare example of a warplane that has kept the tradition going. Motifs of tiger-shark teeth, vipers and, yes, warthogs feature prominently.

But nose art has stayed fresh on certain aircraft, particularly bombers, cargo planes, and the low and slow-flying A-10 Warthog . The US Air Force intends to retire the Warthog in 2022, which means these designs will sadly leave the military with them.

A shift toward low-observable paint schemes also reduced the practice, and most military aircraft today come in standard tactical grey with few creative furnishings, although there was a brief revival during the Persian Gulf War.

Afterwards, "what was once a great morale booster for many in and out of uniform during the war could now only be found fading away on the sides of aircraft in boneyards around the country," aviation journalist Nicholas Veronico wrote in Boneyard Nose Art: U.S. Military Aircraft Markings and Artwork .

An A-10 Warthog with shark teeth paint illustrated to emphasize the 30-millimeter cannon. Photo: US Air Force

So if you see a modern-day Warthog with these teeth, it's a 23rd Fighter Group Warthog, with one exception being the 76th Fighter Squadron, which split off from the 23rd and joined a reserve unit. (They fly with teeth, too.) And these are the only units in the Air Force authorized to have the design.

Remember those old photographs of Warhawks with shark teeth? Whose pilots faced almost impossible odds fighting Japanese Zeros over China? Yeah, that's them. For the modern-day 23rd Fighter Group, the teeth are a pretty big deal.

Warthogs and tiger-shark teeth are almost inseparable in A-10 imagery. But this design (above) is actually reserved for one unit, the 23rd Fighter Group. Nicknamed the "Flying Tigers," the 23rd's teeth are a reference back to its heritage flying P-40 Warhawks in WWII.

Today, the 23rd only flies Warthogs. So without a suitable replacement, the shark teeth might become history. We're pretty confident in surmising that the Air Force's planned substitute for the A-10, the F-35 Joint Strike Fighter , will never have teeth, as that would require painting over its stealthy coatings.

Ah, but wait. The exception to the rule are the A-10's with teeth and tusks, part of the 442nd Fighter Wing at Whiteman Air Force Base, Missouri.

These Warthogs received their teeth last year at the urging of Senior Airman Spencer Stringer, a technician, and his supervisor Master Sgt. Geary Rose, according to an official Air Force news item. The shape and design is slightly different from the Flying Tigers, and the tusks add to the distinction, keeping the 23rd's design exclusive.

"I don't care if the plane goes to the bone yard next week," Stringer said. "If it sits there for the next 30 years it'll have teeth."

Rose added: "It's something I've always wanted to do. If you Google A-10s all you see are ones with teeth. An A-10 has to have teeth."