Plesiosaurs swam like penguins

New simulations might resolve a long-standing debate


FLIP FLAP  New simulations could end years of debate on plesiosaur motoring. The ancient marine reptiles, one illustrated here, most likely swam using their front flippers for power and their back flippers for steering.


Fossil hunter Mary Anning’s 1823 discovery of the first complete plesiosaur skeleton led to more than 190 years of arguing. Some claimed the marine reptile used its four flippers like the oars of a boat. Others countered that the flippers flapped through the water like bird wings.

Experiments with robots and even humans wearing plesiosaur-like flippers only fanned the flames. But a new computer model may finally lay the controversy to rest.

Computer scientist Greg Turk of Georgia Tech in Atlanta and colleagues ran thousands of simulations to find the limb motion that could best propel the creatures forward. Plesiosaurs didn’t flap with all their flippers, nor did they use only their rear flippers to swim, the simulations suggest. Instead, plesiosaurs powered ahead with their two front flippers, using the two back ones like a boat’s rudder to maneuver and maintain stability, the team proposes online December 18 in PLOS Computational Biology

The swimming motion is more birdlike, similar to the underwater stroke penguins use today, the scientists say.

UNDERWATER ACTION Plesiosaurs couldn’t get very far using only their back flippers, simulations suggest. But they covered about the same distance flapping all four flippers or their front flippers only. Researchers concluded that the marine reptile’s swimming would have been most efficient when front flippers paddled and back flippers maneuvered. Liu et al/PLOS ONE 2015

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