• Scientists have revealed that plesiosaur, an unusual underwater reptile that lived 201 million years ago, was a powerful swimmer.
• Numerous fossils documented a global distribution of the group during the Jurassic and Cretaceous periods.
• Whereas sea turtles mainly use their strong forelimbs for propulsion, the plesiosaurs moved all four limbs together, resulting in powerful thrust.
• A plesiosaur from the Triassic, given that these animals had been studied by palaeontologists for nearly 300 years, and never was there one older than Jurassic.
• The scientists bestowed the name Rhaeticosaurus mertensi on the unique fossil.
• According to the findings published in the journal Science Advances, the reconstructed length of the skeleton is 237 cm.
• These long extinct “paddle saurians” propelled themselves through the World’s oceans by employing “underwater flight” — similar to sea turtles and penguins.
• Instead of laboriously pushing the water out of the way with their paddles, plesiosaurs were gliding elegantly along with limbs modified to underwater wings.
• Their small head was placed on a long, streamlined neck.
• The stout body contained strong muscles keeping those wings in motion.

Evolutionary design:

• Compared to the other marine reptiles, the tail was short because it was only used for steering.
• This evolutionary design was very successful, but curiously it did not evolve again after the extinction of the plesiosaurs.
• For the study, the researchers studied a bone sample. Based on the growth marks in the bones, the researchers recognised that species was a fast growing youngster.
• They compared the thin sections with those from young plesiosaurs from the Jurassic and Cretacous.
• “At the end of the Cretaceous, a meteorite impact together with volcanic eruptions lead to an ecosystem collapse, of which plesiosaurs were prominent victims.

Source:TH