MIAMI (AFP).- Fossils of dinosaur skulls unearthed in the midwestern United States have revealed two new species of unusual horned dinosaurs, researchers said Wednesday.

One, nicknamed Judith after the Judith River geological formation in Montana where it was found a decade ago, is about 76 million years old.

Formally named Spiclypeus shipporum, the creature was part of the Chasmosaurine family -- which includes the famous Triceratops -- and had "horns over the eyes, which stuck out sideways from the skull," said the report in the journal PLOS ONE.

This big, lumbering herbivore also had a "unique arrangement of bony spikes that emanated from the margin of the frill," or neck shield.

"Some spikes curled forward while others projected outward."

Researchers found a collection of bones, including parts of the skull, legs, hips and backbone, some of which  showed signs of arthritis and infection, suggesting that the animal may have suffered pain.

It lived for about 10 years, judging by the growth rings inside the bones.

"This is a spectacular new addition to the family of horned dinosaurs that roamed western North America between 85 and 66 million years ago," said lead author Jordan Mallon of the Canadian Museum of Nature.

"It provides new evidence of dinosaur diversity during the Late Cretaceous period from an area that is likely to yield even more discoveries."

Nine dinosaur species have been found in the Judith River Formation, some of which were also found in Alberta.

Spiclypeus, however, appears to be unique to Montana. 

Its name is combination of two Latin words meaning "spiked shield," and shipporum is a nod to the man who found the fossil on his land, Bill Shipp.

"Little did I know that the first time I went fossil hunting I would stumble on a new species," said Shipp, a retired nuclear physicist.

"As a scientist, I'm really pleased that the Canadian Museum of Nature has recognized the dinosaur's value, and that it can now be accessed by researchers around the world as part of the museum's fossil collections."

Utah dino
Another horned dinosaur uncovered in the Wahweap Formation in Grand Staircase-Escalante National Monument in southern Utah was adorned with two spikes rising out of its neck shield.

This one, newly named Machairoceratops cronusi, lived around 77 million years ago and weighed one to two tons.

Its skull features showed it was unlike any previously known centrosaurine, a subfamily of ceratopsids which were characterized by parrot-like beaks, facial horns and ornate neck shields.

"Machairoceratops is unique in possessing two large, forward-curving spikes off of the back of the neck shield," said Eric Lund from the Ohio University Heritage College of Osteopathic Medicine.

He said each spike contained a "channel extending from the base of the spike to the tip, the function of which is currently unknown."



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