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T. Rex May Have Had Lips Like A Modern Lizard's

In movies and TV shows, Tyrannosaurus rex often sports a fleet of big, sharp teeth that are almost always on display. But the dinosaurs and their kin may have kept their pearly whites mostly tucked behind lizardlike lips.

Similar to Komodo dragons today, these dinosaurs had ample soft tissue around the mouth that would have functioned as lips, an analysis of fossilized and modern reptile skulls and teeth finds. The research, described in the March 31 Science, challenges common, traditional reconstructions of how these top predators appeared in life.

"This is a nice, concise answer to a question that has been asked for a long time by dinosaur paleontologists," says Emily Lessner, a vertebrate paleontologist at the Denver Museum of Nature and Science, who wasn't involved in the study. 

Soft tissue is not often included in analyses of the biomechanics of feeding dinosaurs, she says. Acknowledging the potential presence of lips in these tests could change how we think some dinosaurs ate.

It's "not an unfair argument" to suggest that nonavian theropods, the dinosaur group that includes T. Rex, might have had their chompers constantly exposed, says paleontologist Thomas Cullen of Auburn University in Alabama. Their sharp teeth tended to be large, potentially too big to fit fully in the mouth. And crocodiles and their ilk — theropods' closest living relatives that have teeth — lack lips.

But almost all land vertebrates today have liplike coverings for their teeth, Cullen says. Why should Tyrannosaurus and other nonbird theropods be different?

Cullen and his colleagues analyzed fossilized theropod skulls and teeth alongside comparisons of living reptiles. The team examined the pattern of foramina, small passageways through bones, in the upper jaws of theropods and some modern and other extinct reptiles.

Foramina route blood vessels and nerves to the soft tissue around the mouth. In crocodilians, these foramina are scattered across the jaw. But in lipped reptiles like lizards, the little holes are arranged in a line along the edge of the jaw near the teeth. Tyrannosaurus shares this row of jaw pores, the analysis showed.

Enamel in theropod and crocodilian teeth also yielded clues. When enamel dries out, it wears down more easily. The researchers found that the side of alligator teeth that are continually exposed erode more than the wetter side facing the inside of the mouth. Theropods have a more even wear pattern, suggesting the teeth were kept covered and moist. 

And monitor lizards (Varanus spp.), which have proportionally long, serrated teeth much like theropods did, don't decrease their lip coverage with increasing tooth and skull size, the researchers found. Because tooth length and skull size scale similarly in monitor lizards and theropods, the team says, there's no reason to think that theropods couldn't fit their teeth fully in their mouths too.

What's more, the analysis revealed a neat row of jaw foramina in Hesperosuchus, an extinct, very early cousin of crocodilians. That finding suggests that lips may have been present in the earliest archosaurs — the group of reptiles that gave rise to dinosaurs (including birds) and crocodilians. The researchers think lips may have eventually been lost in the crocodilian lineages that survived to the modern day and lost in a separate process in birds.

But paleontologist Thomas Carr, who has studied tyrannosaurs, is not persuaded by the results. The new study "can be summed up in two words: completely unconvincing," says Carr, of Carthage College in Kenosha, Wisc.

In 2017, he and his colleagues showed that tyrannosaurs had a rough, wrinkled surface texture to the jaw bones, and that crocodilians have this same bone texture underlying the lipless, scaly margins of their jaws (SN: 3/30/17).

"In many cases," Carr says, "the soft tissues leave signatures on bone." Those signatures can tell you what sat on top of the bone in animals whose skin or scales haven't been preserved, he says. The new research "completely disregards … the texture of the facial bones, which unambiguously shows that [tyrannosaurs] had flat scales, like in crocodilians, all the way down to the edges of the jaws."

This bone roughness isn't a consistent feature in theropods, Cullen says. Young tyrannosaurs and smaller theropod species had smooth bones similar to a lizard's. It's possible that these animals had lips and then lost them over their life, but "I don't think there is really any modern example of that kind of thing happening," he says.

Something like the discovery of a mummified tyrannosaur carcass with preserved facial tissues, Carr says, could settle the matter of who had lips and who didn't (SN: 10/12/22).

Bag A Swamp Monster: The Ultimate Guide To Florida Iguana Hunting

Green iguanas have been around Florida even longer than Burmese pythons. In some ways, these invasive lizards are an even bigger headache for the state. While pythons thrive mainly in the remote Everglades, iguanas concentrate in populated areas, where their burrows undermine seawalls, sidewalks, canal banks, levees, and other vital infrastructure. They wreak havoc on lawns, gardens, golf courses, and boat docks, and their droppings can spread the Salmonella bacteria to humans. They've also been known to displace threatened native wildlife such as burrowing owls and gopher tortoises. Like pythons, green iguanas can be hunted year-round—and doing so is crucial to managing their population. Here's how to start Florida iguana hunting. 

Related: Hunting Pythons in Florida: How to Get in on the Fun

Can You Hunt Iguanas in Florida?

"Even someone who's never hunted can get in on iguana hunting," says Michael "Trapper Mike" Kimmel, owner-operator of Martin County Trapping and Wildlife Rescue and an outfitter of guided iguana hunts along Florida's inland canals. "I've even had vegans and so-called tree-huggers come out, because they know that in order to help native wildlife, this has to be done."

More experienced hunters will find iguana hunting a fast-paced outing that tests their shooting skills. While full-grown male iguanas can be 5 feet long and weigh nearly 20 pounds, most are much smaller, and Kimmel's preferred method for a humane kill—a shot to the brain—presents a very small target area with little room for error. The action can be fast and furious. On his best day, Kimmel's hunters took 91 swamp lizards.

Florida iguana hunting is great for both novice and experienced hunters. Mike Kimmel

"Florida iguana hunting has become popular because it's high action, low stakes, and just a lot of fun," he says. "You're out on a boat on the water in the sun, it's always a beautiful day, and you can listen to music and talk and be loud with your buddies. Best of all, you get tons of trigger time. There's just not many hunts where you're going to have as good a time while helping the ecosystem and the state in such an impactful manner." 

Where to Hunt Iguanas in Florida

Invasive green iguanas easily blend in with Florida's native foliage, but with a little practice, you can learn to spot their silhouettes in treetops. Favorite basking spots also show telltale signs of their presence. "When I scan a tree I'm looking not only for iguanas but also for places I think an iguana may like—spots where leaves are pushed down or an open spot on a branch where the sun's hitting just right," Kimmel notes. Canal banks, levees, ponds, and lakeshores are good areas to look for their burrows. Water provides important escape cover for the lizards, which are comfortable in both freshwater and saltwater. "They'll often dive into a canal when approached," Kimmel says. "They swim faster than they walk and can hold their breath for a very, very long time." 

Iguanas also favor culverts, drainage pipes, and rock piles, which makes South Florida's extensive man-made canals primo iguana habitat. Since iguanas were first discovered in Florida in the 1960s along Miami-Dade County's southeastern coast, the Central and South American natives have spread northward along both the Atlantic and Gulf coasts. 

How to Legally and Safely Go Florida Iguana Hunting

As with pythons and other destructive invasive species, state regulations allow Florida iguana hunting 365 days a year on private land—with the owner's permission—and on 25 Florida Fish and Florida Fish and Wildlife Conservation Commission (FWC) areas. No permit or hunting license is required, but local laws regarding firearms must be observed. Since most iguanas are found within city limits, air rifles are a popular method of take. "If you're doing this on your own, take it seriously and make sure you have the right equipment," Kimmel urges. "Don't buy some cheap Walmart .177. You want at least a .22 or .25 caliber. I use a .30 caliber." Shooting sticks are a good idea, too, and a quality scope is a must. "Your ideal kill shot is the brain, which is about the size of a dime on the bigger ones," he says. "Shots to the lungs or heart just don't stop them, because they're incredibly tough."

Otto is an iguana retrieving pro. Mike Kimmel

Kimmel is famous for using bird dogs to retrieve iguanas, and his YouTube channel features videos of his Deutsch Drahthaar, Otto, fetching up 5-foot-long lizards bristling with claws and tail spikes. Kimmel doesn't recommend throwing an untrained dog into the field when Florida iguana hunting—a wounded iguana will lash out with its powerful tail, back claws, or vise-grip jaws at anything that tries to pick it up—but he stresses that hunters must do all they can to retrieve and humanely dispatch anything they shoot. "If people just leave them behind to rot, you'll have homeowners complaining and eventually the state will have to shut this down, and we'll be left with absolutely no solution to removing this destructive species from our state."

The FWC recommends the same two-step process to dispatch iguanas used to kill pythons. First, render the lizard unconscious with a blow to the head. Next, deploy a sharp object such as a screwdriver or a knife tip to spike the cranial cavity. Then move the sharp object in circular motions to scramble the brain. Because green iguanas were added to the state's prohibited species list in 2021, it is illegal to transport them live without a permit. That listing also bans acquiring them as pets and mandates that anyone who owned an iguana before the ban must outfit it with a transponder tag and apply for a special permit that must be renewed annually. 

What To Do With Swamp Monsters After the Hunt Male iguanas often become strikingly orange when they mature. Mike Kimmel

They don't call iguanas "the chicken of the trees" for nothing. Many consider these predominantly herbivorous lizards good table fare, though their tendency to scavenge dead animals may give some diners pause. Iguana meat is popular fried, barbecued, in stews, and as a taco filling. Kimmel says he always has people asking for the meat after he goes Florida iguana hunting. If he doesn't plan to give away the meat or cook it himself, he feeds the carcasses to his hogs. Kimmel also skins the iguanas and turns the hides into wallets, purses, and backpacks. Particularly prized are the hides of big males, which take on a vivid orange hue when mature.

T-Rex's Teeth Were Likely Covered By Big Lizard Lips, Say Paleontologists

Duration: 01:07 18 hrs ago

Teeth are probably one of the first things that come to mind when you imagine a T-Rex. But now experts say that unlike the film Jurassic park, where the tyrannosaurus' toothy grin is ever-present, the creature likely had equally big lips to cover those chompers up. The paleontologists say t-rex wasn't the only creature with dino lips either, likely all theropods had them.

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