Scientists have discovered a new species of dinosaur with a mysterious appendage on its back, Christian Science Monitor reports.

Researchers describe the new dinosaur species, Morelladon beltrani, in a paper published Wednesday in the journal "PLOS ONE."

Morelladon beltrani was named after a quarry near the northeastern Spanish city of Morella where the fossil was unearthed in 2013, and in honor of Victor Beltrán, who assisted at the dig sites around the quarry, according to Tech Times.

Researchers are unsure of the purpose of this unique feature to the Morelladon, that roamed the earth some 125 million years ago. A ridge poked up from this plant-eating dinosaur's spine, forming the so-called sail. 

The researchers report that Morelladon was likely similar to Iguanodon bernissartensis and Mantellisaurus atherfieldensis, among others found throughout Europe. 

"It's difficult to know what is the main function or purpose of this tall neural spine," study author Fernando Escaso told The Christian Science Monitor in an interview. 

According to researchers, the medium sized Morelladon was just over eight-feet tall and stretched nearly 20-feet long.

Scientists discovered a partial skeleton Morelladon that consisted of mainly vertebrae and pelvic bones. On the inspection of the vertebrae, the scientists discovered elongated spinal bones that would have protruded vertically from the dinosaur's back, forming the 'sail'.

Dr. Escaso suggested that the sail could be related to thermoregulation, to keep the animals' bodies at a healthy temperature. He added that it could also store extra fat for the animal for periods of low food supply. 

"But we don't have direct evidence," he says. "We only have the bones. We don't have fat, we don't have tissue."

Paul Sereno, a paleontologist at the University of Chicago, who is not connected to the study, said in an interview with the Monitor that the new animal's sail was most likely connected to display, to seem bigger and more attractive to mates.

"We know that probably in the Jurassic, several million years older, the main ecosystem was inhabited by sauropods, long-necked dinosaurs," he says. "But during the Cretaceous, I think that this kind of dinosaur communities was the most important."