The most complete dinosaur fossil ever found in Mississippi, considered “incredibly unusual” by state officials, has remained 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 more than 82 million years ago. The hadrosaur family includes at least 61 identified species, with potentially hundreds more that once roamed the Earth.
Dinosaur remains in Mississippi
The researchers found parts of the vertebrae, forearm, legs and pelvic bones of this specimen. Extracting the remainder of the fault from its location near Booneville in northeastern Mississippi proved challenging.
“This thing sat for a while because there was no one to work on it,” said James Starnes, an official with the state Geological Survey.
A 3D method for forensic bone analysis
For nearly two decades, the specific species of this hadrosaur fossil remained unidentified. Now researchers are using a 3D method of forensic bone analysis called geometric morphometry to solve the mystery before the fossil is fully discovered.
Derek Hoffman, a graduate student in geology at the University of Southern Mississippi (USM), analyzed Hadrosaurus remains using 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 using sophisticated statistical models to identify differences and similarities to known bones.
Dinosaur fossils from Mississippi
Hoffman’s work is complicated by the fact that some parts of the fossil are in the hands of private collectors. His research focused primarily on bones held by the Mississippi Museum of Natural Sciences.
“We have quite a few of the vertebrae,” said the museum’s curator of paleontology, George Phillips. “We have one humerus. We have one ulna. The ulna is the back of the forearm. We have some of the leg bones. Next we have the pubis.
The ulna of an adult hadrosaurus was about two feet long, and the humerus about a foot and a half. The complete leg bones of an adult hadrosaur could exceed 50 pounds in total weight. However, the dinosaur’s skull, the most unique feature for distinguishing hadrosaur species, has yet to be found.
A type of hadrosaur
Different species of hadrosaurs evolved with a wide variety of crowns on their duck heads, including structures like a rooster’s crest. Paleontologists still debate the biological purpose of these features, but their diversity contributed to the recorded diversity of the hadrosaur family.
Hoffman focused on the dinosaur’s pubis, a bone from the front of the pelvis, as the next best choice to identify the type of fossil.
Although the differences between hadrosaur pubic bones 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 potential species of this Mississippian fossil.
Hadrosaurus was probably about 25-26 feet long and about 16 feet tall when it stood on its hind legs.
Well-represented dinosaurs in the fossil record
Researchers believe the hadrosaur lineage began in North America and eventually migrated globally, with fossils found in Asia, South America, Europe and North Africa. “They are without doubt the best-represented dinosaurs in the fossil record,” 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-curved crest, and Edmontosaurus, which had a crest made of soft, rooster-like tissue.
Starnes described the 2007 discovery of the hadrosaur near Booneville as “incredibly unusual.”
“We just don’t have many skeletons. We have bits and pieces, but not a skeleton,” he said. Despite the nearly two decades it took to unearth only a fraction of the fossils, he hopes the project will eventually be completed.
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