Paleontologists studying Plesiosaur fossils have made an interesting discovery about the long-extinct water-dwelling dinosaurs.

According to a team of paleontologists, these ancient sea creatures did not necessarily swim, rather they "flew" underwater, much like modern day sea turtles and penguins. These dinosaurs classified as "paddle saurians" propelled themselves through the oceans by employing "underwater flight"

The team of paleontologists from the University of Bonn, Germany, with colleagues from Japan and France found that the oldest plesiosaur species ever discovered, moved through this unique form of underwater propulsion.

The oldest plesiosaur species comes from the youngest part of the Triassic period and is about 201 million years old.

Plesiosaurs figured out a more efficient way to expend energy while swimming was by gliding instead of furiously pushing water with their modified limbs which they started using like birds use their wings during flight.

Their body structure also enabled them to move in a unique way only a few modern day aquatic animals and birds posses. They had a very small head compared to their long, streamlined neck. They had a very stout body with strong muscles that helped acquire this new movement pattern that we see even today.

This unique way of flying through water minimized their need for propelling their body with their tails, like sharks or whales. Because of this, they had a much shorter tail compared to other marine mammals. They used their tails exclusively as rudders to guide them in the water.

"This evolutionary design was very successful, but curiously it did not evolve again after the extinction of the plesiosaurs," said paleontologist Prof. Martin Sander from the Steinmann Institute of Geology, Mineralogy, and Paleontology of the University of Bonn, according to a Science Daily release.

Modern day sea turtles mainly use their strong forelimbs for propulsion, the plesiosaurs moved all four limbs together which created much more force thrusting the animal further and faster. Analysis of bones also revealed that these ancient animals did not have a shell like turtles.

A private fossil collector named Michael Mertens discovered a truly exceptional specimen during quarrying operations in a clay pit in Westphalia, Germany, in 2013 which led to the discovery by the LWL-Museum für Naturkunde in Münster, Germany.

"I could not believe that there was a plesiosaur from the Triassic, given that these animals had been studied by paleontologist for nearly 300 years, and never was there one older than Jurassic," said Sander who was enthralled by the find and rushed to the site to aid the team.

The team studied the bone samples found using computed tomography. They cut thin sections into the bones and studied them which showed the team that these creatures were tiny as offspring, but grew very fast. In fact the skeleton they found measured 2.3 meters in length, which is a small specimen.

"Plesiosaurs apparently grew extremely fast before reaching sexual maturity," Sander summed up the results. The paleontologists now can confirm that the plesiosaurs were warm-blooded. Since plesiosaurs spread quickly all over the world, "they must have been able to regulate their body temperature to be able to invade cooler parts of the ocean," the team added.

Because of their warm-bloodedness and their efficient locomotion, plesiosaurs were extremely successful and widespread.

The study was published in the journal Science Advances on Dec. 13.