Fossils uncovered in Spain could lead to new clues about how dinosaurs evolved, according to a study published on Sunday in the science journal Papers in Paleontology.

Fidel Torcida Fernandez-Baldor from the Dinosaur Museum of Salas de los Infantes in northern Spain discovered the fossils, which together represent at least five individual dinosaurs.

The musuem focuses on Cretaceous-era fossils.

"From the beginning, we knew these bones were exceptional because of their minute size. It is equally impressive how the study of this animal overturns global ideas on ornithopod dinosaur evolution," he said in a press release from the Vrije Universiteit in Brussels, which contributed to the study.

Plant-eating ornithopods are one of seven major groups of dinosaurs. The name ornithopod means "bird foot" as the dinosaurs stood on two legs. The Iguanodon, which measured up to nine meters (30 feet) in length, is one of the most-popular species of ornithopod.

Fossils of the newly discovered "Foskeia pelendonum" show the dinosaur measured just over half a meter in length, or just under 20 inches. The name Foskeia in Greek, from which many dinosaur names are derived, means something close to "light foraging," according to Vrije Universiteit.

"This is not a 'mini Iguanodon', it is something fundamentally different ... Its anatomy is weird in precisely the kind of way that rewrites evolutionary trees," said Penelope Cruzado-Caballero from Universidad de La Laguna in Spain.

Why is this dinosaur different?

Paleontologists have said they are fascinated by the complexity of Foskeia's tiny skull.

Marcos Becerra ​from Universidad Nacional de Cordoba said, "miniaturization did not imply evolutionary simplicity — this skull is weird and hyper-derived," according to the press release.

Thierry Tortosa of the Sainte Victoire Natural Reserve said that the dinosaur "helps fill a 70-million-year gap, a small key that unlocks a vast missing chapter."

Paul-Emile Dieudonne, from Argentina's National University of Rio Negro, who led the research, wrote that Foskeia's "extreme smallness" was remarkable.

"Yet it preserves a highly derived cranium with unexpected anatomical innovations."

"These fossils prove that evolution experimented just as radically at small body sizes as at large ones. The future of dinosaur research will depend on paying attention to the humble, the fragmentary, the small."

Edited by: Elizabeth Schumacher