A new study on dinosaur fossils has suggested that the creatures may have evolved earlier than thought. Paleontologists re-examined some dinosaur fossils from Chañares Formation of Argentina and found that the remains were misdated before.

Claudia Marsicano, a paleontologist at the University of Buenos Aires, said reanalysis of the fossils hinted that the creatures evolved millions of years earlier than first thought. Chañares Formation, from where the fossils were unearthed, is an important site for paleontologists due to amount of fossils it holds. Experts believe the site can have fossils from early evolutionary dinsauromorphs to many other later dinosaur species.

Paleontologists said analysis of fossilized remains within the Chañares can help in knowing how dinosaurs evolved. Marsicano said, “In other basins, dinosaur precursors, early dinosaurs and faunas dominated by dinosaurs do not all conveniently exist in the same place. In the basin containing the Chañares Formation, you can follow hundreds of meters of sediments back through time”.

Marsicano believes as the site offers the complete history of the creature, margin of error becomes very narrow. During the new study, paleontologists crushed rock samples from the site to extract zircon crystals. Then they measured the exact ration of uranium to lead in the crystals. The process allows the paleontologists to date the samples.

According to the study, dinosaurs that lived in the site could be about 5 to 10 million years younger than thought earlier.