What Caused Holes in Sue the T. Rex’s Jawbone? Scientists Are Stumped

The mounted fossil of a Tyrannosaurus rex known as Sue is pictured at the Field Museum in Chicago, Illinois, US, in this undated handout image obtained by Reuters on September 30, 2022. (Lucy Hewett, Field Museum/Handout via Reuters)
The mounted fossil of a Tyrannosaurus rex known as Sue is pictured at the Field Museum in Chicago, Illinois, US, in this undated handout image obtained by Reuters on September 30, 2022. (Lucy Hewett, Field Museum/Handout via Reuters)
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What Caused Holes in Sue the T. Rex’s Jawbone? Scientists Are Stumped

The mounted fossil of a Tyrannosaurus rex known as Sue is pictured at the Field Museum in Chicago, Illinois, US, in this undated handout image obtained by Reuters on September 30, 2022. (Lucy Hewett, Field Museum/Handout via Reuters)
The mounted fossil of a Tyrannosaurus rex known as Sue is pictured at the Field Museum in Chicago, Illinois, US, in this undated handout image obtained by Reuters on September 30, 2022. (Lucy Hewett, Field Museum/Handout via Reuters)

Sue, the biggest and best-preserved Tyrannosaurus rex ever unearthed, no doubt was a fearsome beast when this predator prowled what is now South Dakota about 67 million years ago at the twilight of the age of dinosaurs.

But even this huge dinosaur, whose fossils are displayed at the Field Museum in Chicago, was not invulnerable. A prime example of this is the series of circular holes in Sue's jawbone that continue to baffle scientists. New research seeking an explanation for these holes has managed to rule out one major hypothesis, though the answer remains elusive.

Researchers said a close examination of the eight holes - some the diameter of a golf ball - on the back half of Sue's left lower jawbone, or mandible, determined that they were not caused by a type of microbial infection as some experts had proposed.

The holes were found to differ from bone damage caused by such an infection, said Bruce Rothschild, a medical doctor and research associate at the Carnegie Museum of Natural History in Pittsburgh, lead author of the study published this week in the journal Cretaceous Research.

Sue, measuring 40-1/2 feet long (12.3 meters), represents one of the world's best-known dinosaur fossils. Tyrannosaurus was one of the largest land predators ever, inhabiting western North America at the end of the Cretaceous Period.

Field Museum paleontologist and study co-author Jingmai O'Connor noted that about 15% of all known T. rex specimens have holes similar to Sue's.

The researchers explored whether the holes had been caused by an infection involving microbes called protozoans. One common protozoan disease known to occur in birds, which evolved from feathered dinosaurs, as well as in people is called trichomoniasis, caused by a parasitic protozoan. Trichomoniasis in people, though not birds, is a sexually transmitted disease.

O'Connor noted that one falcon diagnosed with trichomoniasis had shown damage in its jaw, but it differed from Sue's holes.

The bone around Sue's holes showed signs of healing, indicating that whatever caused them did not kill the animal. Similarities were observed between Sue's healing and the healed breaks in other fossilized bones as well as healing bone seen around holes made in the skulls of ancient Inca people in Peru.

The cause of Sue's holes remains a puzzle.

Rothschild proposed the possibility of claw damage during mating, or as he put it: "mounting from back or top with claws striking the posterior mandible." Sue has a feminine name - honoring the woman who discovered the fossils in 1990 - but the dinosaur's sex is unknown.

"I honestly have no clue what formed them," O'Connor said. "I really do not think they are bite marks or claw marks."

"A pathology that commonly affected T. rex individuals, that caused large holes to open up in the jawbone but only in the back of the jawbone, but didn't kill the T. rex because the holes started to heal, at least in Sue - it's weird," O'Connor added. "So many hypotheses have been put forth only to be shot done. It's a good paleontology mystery - my favorite."

The holes were not the only examples of damage endured by Sue, a dinosaur that lived about 33 years.

"Sue was quite old when it died and it shows numerous injuries and pathologies," O'Connor said. "It had gout in its hands. It had fallen on its right side, busting its ribs - they healed, though. It had torn a ligament in the right arm - healing. It had a horrible bone infection in its left leg. It had arthritis in its tail. It would not have been a happy camper the last year of its life."



UN Ocean Conference Sets Sail Off France on World Oceans Day

People take photos of vessels during the "Ocean Wonders" event in honor of World Oceans Day ahead of the UN Ocean Conference on Sunday, June 8, 2025, in Nice, France. (AP Photo/Annika Hammerschlag)
People take photos of vessels during the "Ocean Wonders" event in honor of World Oceans Day ahead of the UN Ocean Conference on Sunday, June 8, 2025, in Nice, France. (AP Photo/Annika Hammerschlag)
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UN Ocean Conference Sets Sail Off France on World Oceans Day

People take photos of vessels during the "Ocean Wonders" event in honor of World Oceans Day ahead of the UN Ocean Conference on Sunday, June 8, 2025, in Nice, France. (AP Photo/Annika Hammerschlag)
People take photos of vessels during the "Ocean Wonders" event in honor of World Oceans Day ahead of the UN Ocean Conference on Sunday, June 8, 2025, in Nice, France. (AP Photo/Annika Hammerschlag)

Dozens of research and exploration vessels from around the world set sail just off the French coastal city of Nice on Sunday to kick off the third UN Ocean Conference and pay tribute to World Oceans Day.

The event, themed “Ocean Wonders,” saw the vessels sail across Nice's Baie des Anges, or Bay of Angels, to spotlight the beauty and importance of the ocean while urging world leaders not to lose sight of its value as they make decisions about the planet’s future.

Thousands of delegates, including heads of state, scientists, and environmental advocates, are expected in Nice this week to confront growing threats to the ocean, and the need to transform pledges into protection.

The United Nations has called the threats a global emergency facing the world’s oceans as they confront rising temperatures, plastic pollution choking marine life, and relentless overexploitation of fish and other resources.

Just 2.7% of the global ocean is effectively protected from destructive activities like industrial fishing and deep-sea mining — far below the global goal of 30% by 2030, The Associated Press reported.

Participating boats included the Energy Observer, a solar-panel covered catamaran that was the first vessel to circumnavigate the globe using renewable energy alone. It produces hydrogen fuel on board via seawater electrolysis, offering a vision of zero-emissions maritime travel.

Other standout vessels included France’s Alfred Merlin, dedicated to underwater archaeology; the OceanXplorer, a high-tech billionaire-owned research yacht; and the WWF’s Blue Panda, which is working to map and protect the last remaining seagrass meadows in the Mediterranean Sea.

At the heart of the conference is the push to ratify the High Seas Treaty, adopted in 2023. If it takes effect, the treaty would for the first time allow countries to establish marine protected areas in international waters, which cover nearly two-thirds of the ocean and remain largely ungoverned.

“The High Seas Treaty is critical to ensuring we can protect biodiversity in the ocean,” said Rebecca Hubbard, director of the High Seas Alliance. “We’re in the middle of a biodiversity and climate crisis. We absolutely have to protect the ocean to address those crises.”

But even in waters already designated as protected, enforcement often falls short. Many countries, France included, face criticism from environmental groups over weak regulation and continued industrial activity within their marine protected areas.

“The ambition is not there, the speed is not there, and the scale has not been there,” said Sílvia Tavares, project manager at Oceano Azul Foundation. “Moments like UNOC are key to changing that.”

Several countries are expected to announce new marine protected areas, or MPAs, during the conference, along with bans on bottom trawling and other destructive activities within their existing MPA networks.

The “Ocean Wonders” fleet will remain docked in Nice and open to the public until the conference concludes on June 13.