BIG PLIOSAUR UPDATE UPDATE

[darren.naish@port.ac.uk]

First off, congrats to Ben for his article on the giant pliosaurs and 
the other plesiosaur stuff at his site - it's fantastic, though 
unfortunately :) covers much the same stuff as my website does (I 
have already written a whole page on giant pliosaurs and may as well 
retain it) [Once I finish the text on giant geckos, kiwis and 
placodonts I will start to go live. Whoever identifies Ermentrude the 
lizard (to species level) wins a prize].

My understanding of the giant Oxford Clay pliosaurs is a bit 
different from what Ben says in the article. Ben's source was Colin 
McHenry, and seeing as Colin is specialising in pliosaurs for his 
phd, his information is surely reliable BUT I have had many 
conversations about these fossils with Dave Martill, the 
palaeontologist responsible for much of the publicity Colin's 
discovery received. Last time I spoke to Dave about the giant one 
(it is based on a vertebra famously painted blue and used as a 
doorstop (the blue paint was presumably added for aesthetic 
reasons)), I was told that Arthur Cruickshank (responsible for the 
bone's reidentification as from a sauropod) had changed his mind and 
was saying that, after all, is IS from a pliosaur. I will try and 
confirm this with Dave when he returns from the field (as the 
specimen allegedly lacks subcentral foramina its ID as plesiosaurian 
is suspect). 

Other than its informal naming as 'Megapleurodon', nothing more has 
come of the specimen. Dave has suggested in popular articles and 
interviews that the bone might represent an extra-large 
_Liopleurodon_. I'm not keen on this idea as I suspect that 
plesiosaurs had determinate growth and a specimen perhaps 20% bigger 
than other very large liopleurodons would be a cause of suspicion. 
When (funnily enough), Dave and I argued about this issue only a few 
weeks ago, he said that there was no reason why the specimen _should_ 
be regarded as from _Liopleurodon_ - - however, the two of us agree 
to differ on the issue of niche partitioning and ecological 
differentiation amongst Oxford Clay pliosaurs. I reckon that 
different large and very large pliosaurs were living alongside one 
another, but avoiding competition by concentrating on different size 
prey and by using different foraging methods. Much the same 
suggestion has been made for contemporaneous nothosaurs and also goes 
for extant cetaceans and pinnipeds. However, Dave disputes this and 
points out that the Oxford Clay represents 3 million years of 
deposition. I confess I don't know the dating of the ammonite zones 
well enough to know which pliosaurs truly were contemporaneous, but.. 
it's something to think about. 

Niche partitioning in these pliosaurs is something Leslie Noe will 
have something to say about sometime in the near future (and an 
exciting new discovery sheds more light on this topic - stay tuned!).

Also, there is much more evidence for huge Oxford Clay pliosaurs than 
just this one vertebra. IN the BMNH collections there are also some 
absurdly enormous snout and lower jaw fragments. 

"As you are awarre, our blocade is completely legal"
Jar Jar wasn't *that* bad. Hooray for pod racing.

DARREN NAISH 
PALAEOBIOLOGY RESEARCH GROUP
School of Earth, Environmental & Physical Sciences
UNIVERSITY OF PORTSMOUTH
Burnaby Building
Burnaby Road                           email: darren.naish@port.ac.uk
Portsmouth UK                          tel: 01703 446718
P01 3QL                               [COMING SOON: 
http://www.naish-zoology.com]