Fossils of a prehistoric fish are revealing important details about the earliest vertebrate life on earth. A discovery was made that shows jaws evolved in animals that have backbones.

On Wednesday, researchers described the fossil specimens of the fish that were uncovered at the Burgess Shale in the Canadian Rockies. Many of the fossils were preserved, which allowed scientists to study their body structures.

The fish is called the Metaspriggina, and scientists said that it lived around 515 to 500 million years ago during the Cambrian Period. The Metaspriggina grew around two inches long and had no jaws. It had a tapering and narrow body, accompanied by a small head. It also had large eyes and small nasal sacs.

Major fossil find in our Rocky Mtn Burgess Shale: Fossils of Metaspriggina shed new light on rapid evolution pic.twitter.com/BBbxH9GAQ7

— Erin Lawrence (@tvchick13CTV) June 11, 2014

However, Jean-Bernard Caron, one of the study authors from the Royal Ontario Museum in Toronto, said that the structures near the gills of the fish show the antecedent of a jaw.

The Metaspriggina is one of the creatures that started the lineage of animals with backbones, including jawed fishes, birds, mammals, amphibians, reptiles, and even people.

Caron said that studying fossils of the Metaspriggina allows us to have an understanding of where we came from and what our distant relatives might have looked like.

“Metaspriggina is important because it fills an important gap in our understanding of the early evolution of the group to which we belong, but in particular shows with remarkable clarity the arrangement of the so-called branchial arches,” paleontologist from University of Cambridge Simon Conway Morris said.

The Metaspriggina had seven pairs of gill arches that were used for respiration and for filtering food particles. The first pair were said to be more robust than the others, and may be the first step in the evolution of a working jaw, said Caron.

A portion of the jaw bones eventually developed into middle ear bones in mammals. Caron said that this development of the arches into jaw bones made a great impact on how backbones appear and function today.

Image via YouTube