T rex was the king of chomp

"How big were T. rex teeth?" asked a young patron from the Schaumburg Township District Library.

Stomping around the North American west - Canada, Wyoming, Utah, Texas, New Mexico - and across the Pacific Ocean in Mongolia, Tyrannosaurus rex was a gigantic, carnivorous bully the size of a semi-truck, comically fitted with tiny arms.

These creatures lived during the dinosaur era's final chapter, around 68 million to 65 million years ago. The giant lizard gobbled almost anything in its way.

Its teeth were so strong, one bite could deliver 8,000 pounds of force, according to a recent Washington Post report, making T. rex the king of the chomp, with a more powerful bite than any other dino. The jaws, teeth and the roof of its mouth were designed to dispose of entire animals, bones and all, and its oversized appetite sometimes drove a T. rex to devour its own kind.

Rockford's Burpee Museum of Natural History is home to Jane, a teenage T. rex. She was uncovered in the Hell Creek formation in Montana, where she once roamed alongside prehistoric creatures that slogged through swamps and across rivers.

Back when T. rexes roamed the earth, the Pacific Northwest was part of an island called Laramidia, possibly connected to Mongolia by a land bridge.

Jane is the most complete dinosaur of her type. About 90 percent of Jane's bones were carefully extracted from rock, including teeth, and she's on display at the museum. Jane is 22 feet long compared to adult T. rexes, whose skeletons are about 40 feet in length.

T. rex teeth are some of the largest in the dinosaur kingdom and their jaws were jammed with quite a mouthful, even at birth.

"T. rexes had at least 60 teeth when they're born," said Dennis Harezlak, Burpee Museum executive director. "Jane has 71."

Her bones and teeth answer some interesting questions - how old she was when she died and where she lived. With permission from the U.S. Bureau of Land Management, which has jurisdiction over the site of the dinosaur dig, the museum's field team sliced one of Jane's bones in half and counted rings to determine her age, coming up with somewhere between 11 and 12 years old.

The tooth size, about 20 inches, is about half the size of an adult T. rex tooth. Harezlak said Jane's bone color, a caramel-brown, answers the question of where she's from - Montana. Dino bones that are gray in color hail from Utah, where dig sites are brimming with fossilized prehistoric creatures.

Jane's skull, made up of 30 bones, is punctured with four teeth marks. Experts can only guess how that happened. Maybe the bite was a punishment handed to a rowdy youngster, or rough play between two dinosaur kids.

Whatever the reason, Jane was ferociously attacked and marked by wounds that pierced through her face near her mouth. That's not what killed her, Harezlak said.

"One of our board members is a radiologist and he examined the marks. They are old marks, probably done when Jane was 8 or 9 years old, which later rounded and healed."

Harezlak enjoys taking museum visitors aside and showing them real dinosaur teeth housed in the back area of the museum.

"T. rex teeth are razor sharp, like a knife in your drawer, and serrated," he said. "Our visitors become very excited when we place the teeth in their hands."

Like a shark, T. rex had smaller teeth poking out of the jawline pushing through larger, more mature teeth. A fully mature tooth grew up to four feet in length. T. rex teeth are found at many dig sites, sometimes lodged in the fossilized skeletons of other animals.

Until recently, scientists questioned whether Jane was truly a juvenile T. rex, since teenage dinosaur remains are extremely rare. Harezlak cites recent research suggesting dinos that survived beyond infancy usually made it to adulthood.

Skeletons like Jane's offer researchers an opportunity to gain a better understanding of how dinosaurs grew and matured, noting changes in features as dinosaurs reached their 20s. It's up to future paleontologists to solve the mystery as to Jane's cause of death.

Full body casts of the teen T. rex are on view at five other museums around the world. The museum's field team is now at a dig site in Utah, where they are uncovering Jimmy, a juvenile long-necked diplodocus. The dig area promises to provide many more dinosaur, fish and plant fossils.

Want to join the team? Teens ages 15 and older, accompanied by an adult, can join the Burpee Museum field team on a dino dig in Utah or Montana. See the museum website www.burpee.org for more information.

Check it out

The Schaumburg Township District Library suggests these titles on dinosaurs:

• "How To Be a Dinosaur Hunter: Your Globe-Trotting, Time-Traveling Guide," by Scott Forbes

• "Dinosaur Discoveries," by Gail Gibbons

• "Dinosaur Mummies: Beyond Bare-Bone Fossils," by Kelly Milner Halls

• "Dinosaur," by David Norman

• "What Was The Age of the Dinosaurs?" by Megan Stine