The most complete dinosaur fossil found in Mississippi, considered “extremely 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 hundreds more that may have once roamed the Earth.
The dinosaur remains in Mississippi
Researchers have discovered parts of the vertebrae of the spine, forearm, legs and pelvic bones of this specimen. However, extracting the rest of the fossil from its location near Booneville in northeastern Mississippi has proven challenging.
“This thing sat for a while because we didn’t have anybody working on it,” said James Starnes, an official with the state’s geological bureau.
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 revealed.
Derek Hoffman, a graduate student in geology at the University of Southern Mississippi (USM), is analyzing hadrosaur 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 through complex statistical models to identify differences and similarities to known bones.
Dinosaur Fossils of Mississippi
Hoffman’s work is complicated by the fact that some parts of the fossil are in the hands of private collectors. His research primarily focuses on bones held by the Mississippi Museum of Natural Science.
“We have quite a few vertebrae,” said the museum’s curator of paleontology, George Phillips. “We have a humerus. We have an ulna. The ulna is the back of the forearm. We have some of the leg bones. Then we have pubis.”
The ulna of the adult hadrosaur is about two feet long and the humerus is about a foot and a half. The leg bones of a fully grown hadrosaur can exceed 50 pounds in total weight. However, the dinosaur skull, the most unique distinguishing feature of the hadrosaur species, has yet to be found.
Types of Hadrosaurs
Different species of hadrosaurs evolved with a wide variety of crowns on their duck 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 diversity of the hadrosaur family.
Hoffman is focusing on the dinosaur’s pubis, a bone from the front of the pelvis, as the next best bet for identifying the fossil’s species.
Although the differences between the pubic bones of hadrosaur species are often too subtle to the naked eye, rigorous mathematical approaches such as geometric morphometrics can reveal hidden differences. With these methods, Hoffman hopes to narrow down the possible species of this Mississippian fossil.
The hadrosaur was likely about 25-26 feet tall and was about 16 feet tall when it sat on its hind legs.
Dinosaurs well represented in the fossil record
Researchers believe that the lineage of hadrosaurs began in North America and eventually migrated globally, with fossils found in Asia, South America, Europe and North Africa. “They are the most represented dinosaurs in the fossil record, without a doubt,” Hoffmann said.
Hadrosaurs, whose name comes from the ancient Greek for “strong lizard,” ranged from about 2.2 to 4.4 tons. Examples of hadrosaur species include Parasaurolophus, known for its long, backward-curving crest, and Edmontosaurus, which had a crest made of soft tissue like a turkey.
Starnes described the 2007 hadrosaur discovery near Booneville as “incredibly unusual.”
“We just don’t have many skeletons. We have bits and pieces, but no skeleton,” he said. Despite the nearly two decades it has taken him to uncover just one part of the fossil, he hopes the project will eventually be completed.
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