[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Plesiosaur Forelimb-Dominated Underwater Flight (free pdf)



Ben Creisler
bcreisler@gmail.com


The paper is now available:

Shiqiu Liu, Adam S. Smith, Yuting Gu, Jie Tan, C. Karen Liu & Greg Turk (2015)
Computer Simulations Imply Forelimb-Dominated Underwater Flight in Plesiosaurs.
PLoS Computational Biology 11(12): e1004605
doi:10.1371/journal.pcbi.1004605
http://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1004605

Plesiosaurians are an extinct group of highly derived Mesozoic marine
reptiles with a global distribution that spans 135 million years from
the Early Jurassic to the Late Cretaceous. During their long
evolutionary history they maintained a unique body plan with two pairs
of large wing-like flippers, but their locomotion has been a topic of
debate for almost 200 years. Key areas of controversy have concerned
the most efficient biologically possible limb stroke, e.g. whether it
consisted of rowing, underwater flight, or modified underwater flight,
and how the four limbs moved in relation to each other: did they move
in or out of phase? Previous studies have investigated plesiosaur
swimming using a variety of methods, including skeletal analysis,
human swimmers, and robotics. We adopt a novel approach using a
digital, three-dimensional, articulated, free-swimming plesiosaur in a
simulated fluid. We generated a large number of simulations under
various joint degrees of freedom to investigate how the locomotory
repertoire changes under different parameters. Within the biologically
possible range of limb motion, the simulated plesiosaur swims
primarily with its forelimbs using an unmodified underwater flight
stroke, essentially the same as turtles and penguins. In contrast, the
hindlimbs provide relatively weak thrust in all simulations. We
conclude that plesiosaurs were forelimb-dominated swimmers that used
their hind limbs mainly for maneuverability and stability.

Author Summary

Plesiosaurs are an extinct group of Mesozoic marine reptiles with a
global distribution that spans 135 million years. They maintained a
unique body plan with two pairs of large wing-like flippers throughout
their long evolutionary history, but how plesiosaurs swam has remained
a topic of debate for almost 200 years. We address the question of how
plesiosaurs swam using a digital, three-dimensional, free-swimming
model of a plesiosaur in a simulated fluid. We performed thousands of
simulations under different parameters to investigate possible
plesiosaur swimming patterns. Our simulations show that the forelimbs
provide the majority of thrust, and that the thrust from the hindlimbs
is weak. The plesiosaur swims primarily with its forelimbs using an
underwater flight stroke, essentially the same as turtles and
penguins.