The most complete dinosaur fossil ever uncovered in Mississippi, called 'incredibly unusual' by state officials, still remains 85 percent buried since its 2007 discovery.

Paleontologists have confirmed that the specimen was once a living hadrosaur: a family of vegetarian, duck-billed dinosaurs that existed over 82 million years ago.

But the hadrosaur is a large family of herbivore giants — including at least 61 identified, individual species with possibly hundreds of unique kinds having once roamed the Earth, according to experts.

Researchers have secured pieces of this specimen's spinal vertebrae, portions of its forearm, feet and pelvic bones, but the rest has proven tricky to unearth from its location outside Booneville in the northeast part of the state.

'This thing sat for a while because we didn't have anybody to work on it,' as one official with the state's geology office, James Starnes, confessed.

For nearly two decades, it has remained a mystery exactly which of the many species of hadrosaur was actually the kind dug up in this Booneville, Mississippi-area find. 

But researchers are now turning to a 3D method of forensic bone analysis to solve the riddle before it's even fully unearthed. 

University of Southern Mississippi (USM) geology graduate student Derek Hoffman is now analyzing the hadrosaur's remains with this method, which is known across multiple scientific disciplines as 'geometric morphometrics.'

'What geometric morphometrics does,' as Hoffman simplified it, 'is it takes a shape-analysis approach.'

Key features or 'landmarks' are determined for a given bone sample and their respective distances, and the ratios of those distances, are then compared via complex statistical models to confirm differences and similarities to known bones. 

The method has also proven effective in anthropology as well as in studies of human evolution, including comparisons between the brain cavities of modern humans and our Neanderthal ancestors.

But Hoffman's hunt for answers about this hadrosaur fossil has been made harder by the fact that some pieces of the creature are in the hands of private collectors.

Hoffman's work is focused mainly on the bones held publicly by the Mississippi Museum of Natural Science.

'We have quite a few of the vertebrae,' museum paleontology curator George Phillips told local paper the Clarion Ledger. 'We have one humerus.' 

'We have one ulna. The ulna is the posterior of the forearm.'

'We have some of the foot bones,' Phillips continued. 'Then we have the pubis.'

The adult hadrosaur's ulna comes in at roughly two feet long and its humerus bone is in the range of about a foot and a half long. And just one completed, adult hadrosaur's foot bones can exceed well 50 pounds in total weight. 

But the dinosaur's skull — the most unique identifying feature for differentiating between hadrosaur species — has to researchers' frustration yet to be located.

Different species of hadrosaur are well known to have evolved with a wide and weird variety of crowns on their duck-billed heads, even floppy material like a rooster's red 'comb.' 

Paleontologists are still debating what biological purpose these unusual and sometimes ostentatious features might have served, but their variety has contributed to the recorded diversity of the hadrosaur family.

Hoffman at USM has focused on the dinosaur's pubis, a bone from the front of the pelvis, as the next best choice for identifying this fossil's species.

While the differences between hadrosaur species' pubis bones are subtle, often too subtle for the naked human eye, their hidden distinctions can be teased out by rigorous mathematical approaches like geometric morphometrics.

The USM geology grad student is hoping to at least narrow down the number of potential hadrosaur species that this Mississippi fossil might be.

Or: 'What is the lowest taxonomy level we can get this hadrosaur to,' as Hoffman phrased it. 

What's now known about this particular hadrosaur is that it likely measured about 25-26 feet long and stood about 16 feet tall when perched on its hind legs. 

While researchers believe that the hadrosaur lineage started in North America, the plant-eaters eventually migrated across the globe with fossils uncovered in Asia, South America, Europe and North Africa.

'They're the most well-represented dinosaurs in the fossil record,' Hoffman said, 'without a doubt.'  

Hadrosaurs' name derives from the Ancient Greek for 'stout lizard,' and the heavy animals did in fact range from about 2.2 to 4.4 US tons (or between 2,000 to 4,000 kilograms).

Many hadrosaur species lived between 75 and 65 million years ago in the Late Cretaceous Period.

Other examples of dinosaurs from the hadrosaur family include the Parasaurolophus, which had a long, backward-curving crest on its head and appears in the 2022 film 'Jurassic World Dominion,' and the Edmontosaurus, which had the aforementioned crest made from soft tissue like a rooster.

State official James Starnes, with the Mississippi Department of Environmental Quality's Office of Geology, said that the 2007 discovery of this hadrosaur in near Booneville was just 'incredibly unusual.' 

'We just don't have a lot of skeletons,' Starnes said. 'We have pieces and parts, but not a skeleton.' 

Starnes hopes that, despite the nearly two decades it has taken to unearth just a fraction of this hadrosaur fossil, that the project will one day be completed. 

'We're still getting more of this specimen out,' Starnes said.