The most complete dinosaur fossil found in Mississippi, described by state officials as “incredibly unusual,” 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 once roaming the Earth.
The dinosaur remains in Mississippi
Scientists discovered parts of the specimen’s spinal vertebrae, forearms, feet, and pelvic bones. However, extracting the rest of the fossil from its location near Booneville in northeast Mississippi proved challenging.
“This thing sat for a while because we didn’t have anybody working on it,” said James Starnes, an official with the state Geological Survey.
3D method of forensic bone analysis
For nearly two decades, the specific species of this hadrosaur fossil remained unidentified. Scientists are now 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), uses this method to analyze hadrosaur remains. “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 complex statistical models to identify differences and similarities to 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 bones held by the Mississippi Museum of Natural Science.
“We have quite a few vertebrae,” said paleontology museum curator George Phillips. “We have one humerus. We have one ulna. The ulna is the back of the forearm. We have some leg bones. Then we have the pubis.”
The ulna of an adult hadrosaur measures about two feet in length, and the humerus is about a foot and a half. The leg bones of a complete adult hadrosaur can exceed a total weight of 50 pounds. However, the dinosaur skull, the most unique feature for distinguishing hadrosaur species, has not yet been found.
A species of hadrosaur
Different species of hadrosaurs evolved with a wide variety of crests on their duck-billed heads, including structures like a rooster’s comb. Paleontologists still debate the biological purpose of these features, but their diversity contributed to the recorded diversity of the hadrosaur family.
Hoffman is targeting the dinosaur’s pubis, a bone from the front of the pelvis, as the next best bet for identifying the type of fossil.
Although differences between hadrosaur pubic bones are often too subtle to the naked eye, rigorous mathematical approaches such as geometric morphometrics can reveal hidden differences. Hoffman hopes to use these methods to narrow down the potential species of this Mississippian fossil.
The hadrosaur probably measured about 25-26 feet in length and was about 16 feet tall when sitting on its hind legs.
Dinosaurs are well represented in the fossil record
Scientists believe that 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 a doubt the best-represented dinosaurs in the fossil record,” Hoffmann said.
Hadrosaurs, whose name comes from the ancient Greek for “stout lizard,” ranged in size from 2.2 to 4.4 tons. Examples of hadrosaurs include Parasaurolophus, known for its long, backward-curving crest, and Edmontosaurus, which had a crest made of soft tissue like a rooster.
Starnes described the 2007 discovery of a hadrosaur near Booneville as “incredibly unusual.”
“We just don’t have many skeletons. We have bits and pieces, but not the skeleton,” he said. Despite the nearly two decades it took to uncover just a fraction of the fossil, he hopes the project will eventually be completed.
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