PLESIOSAUR FLIGHT REVISED?

[darren.naish@port.ac.uk]

Dan asked about Lingham-Soliar's most recent paper (Plesiosaur
locomotion: Is the four-wing problem real or merely an atheoretical
exercise? _N.Jb. Geol. Palaont.Abh._ 217: 45-87).  Though I've read 
popular versions of this paper's content, I haven't seen it, so I'll 
withhold judgement so the following is not a critique: just some 
thoughts.

While L-S may have a point about the different shapes of the fore- and 
hindflippers, and about the fact that hydrofoils cannot function 
simultaneously as rudders, it strikes me as a bit of step backwards to 
argue that plesiosaurs only flew with one set of limbs. As we all know, 
plesiosaurs have requisite musculature for a powerful downstroke, but 
not for a powerful upstroke. Apparently - unlike turtles and penguins - 
they can only generate propulsion during the downstroke, and the 
beauty of the alternating downstroke theory (of Robinson, Riess and 
Frey) is that there is continual propulsion from both sets of limbs. 

Also, why would some plesiosaurs (i.e. most pliosaurs) have bigger 
'steering' limbs than flying ones? And why is the hindlimb musculature 
for downstroke about as powerful as that for the forelimb downstroke?

"Craig's in the bedroom, asleep like a kitten
  This man could sleep, for the whole of Great Britain"

DARREN NAISH 
PALAEOBIOLOGY RESEARCH GROUP
School of Earth, Environmental & Physical Sciences
UNIVERSITY OF PORTSMOUTH
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