The most complete dinosaur fossil found in Mississippi, considered “incredibly unusual” by state officials, remains 85 percent buried since its discovery in 2007.

Paleontologists have identified the specimen as a hadrosaur, a family of duck-billed, herbivorous dinosaurs that lived over 82 million years ago. The hadrosaur family includes at least 61 identified species, with potentially hundreds more having once roamed the Earth.

Dinosaur remains in Mississippi

Researchers have unearthed portions of the spinal vertebrae, forearm, feet, and pelvic bones of this specimen. However, extracting the rest of the fossil from its location near Booneville in northeast Mississippi has proven challenging.

“This thing sat for a while because we didn’t have anybody to work on it,” said James Starnes, an official with the state’s geology office.

3D method of forensic bone analysis

For nearly two decades, the specific species of this hadrosaur fossil remained unidentified. Researchers are now using a 3D method of forensic bone analysis called geometric morphometrics to solve the mystery before the fossil is fully unearthed.

Derek Hoffman, a geology graduate student at the University of Southern Mississippi (USM), is analyzing the hadrosaur’s remains with this method. “What geometric morphometrics does is it takes a shape-analysis approach,” he explained.

This method determines key features or ‘landmarks’ for a given bone sample and compares their distances and ratios via complex statistical models to identify differences and similarities with known bones.

Mississippi dinosaur fossils

Hoffman’s work is complicated by the fact that some pieces of the fossil are in the hands of private collectors. His research primarily focuses on the bones held by the Mississippi Museum of Natural Science. 

“We have quite a few of the vertebrae,” said Museum paleontology curator George Phillips. “We have one humerus. We have one ulna. The ulna is the posterior of the forearm. We have some of the foot bones. Then we have the pubis.”

The adult hadrosaur’s ulna measures about two feet long, and the humerus is around a foot and a half. A complete adult hadrosaur’s foot bones can exceed 50 pounds in total weight. However, the dinosaur’s skull, the most unique feature for differentiating hadrosaur species, has yet to be found.

Hadrosaur species 

Different hadrosaur species evolved with a wide variety of crowns on their duck-billed heads, including structures like a rooster’s comb. Paleontologists are still debating the biological purpose of these features, but their diversity has contributed to the recorded variety of the hadrosaur family.

Hoffman is focusing on the dinosaur’s pubis, a bone from the front of the pelvis, as the next best choice for identifying the fossil’s species. 

Although differences between hadrosaur species’ pubis bones are often too subtle for the naked eye, rigorous mathematical approaches like geometric morphometrics can reveal hidden distinctions. With these methods, Hoffman hopes to narrow down the potential species of this Mississippi fossil.

The hadrosaur likely measured about 25-26 feet long and stood around 16 feet tall when perched on its hind legs. 

Well-represented dinosaurs in the fossil record 

Researchers believe that the hadrosaur lineage started in North America and eventually migrated globally, with fossils found in Asia, South America, Europe, and North Africa. “They’re the most well-represented dinosaurs in the fossil record, without a doubt,” Hoffmann said.

Hadrosaurs, whose name comes from the Ancient Greek for “stout lizard,” ranged from about 2.2 to 4.4 tons. Examples of hadrosaur species include the Parasaurolophus, known for its long, backward-curving crest, and the Edmontosaurus, which had a crest made from soft tissue like a rooster.

Starnes described the 2007 hadrosaur discovery near Booneville as “incredibly unusual.” 

“We just don’t have a lot of skeletons. We have pieces and parts, but not a skeleton,” he said. Despite the nearly two decades it has taken to unearth just a fraction of the fossil, he hopes the project will eventually be completed.

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