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GIANT PLIOSAURS *AGAIN*



Someone (dammit, I deleted the header and you haven't put your name as a footer)
asked..

> Anyway... does anybody have any idea what the largest species of
> plesiosaur is? Is that title still held by the short-necked variety
> Kronosaurus, or has there been a new discovery... I thought I'd gotten
> a report on a larger species being found recently.

Colin McHenry has addressed this subject quite well on the list before, so check
the list archives and go thru his posts for a competent response. But here's
what I know anyway. _Kronosaurus queenslandicus_ - and it's no longer certain
that Romer's famous specimen (the one restored at Boston) is of the same taxon
as the big thing that turns up in Queensland - is now outclassed, and in fact
has been for a while. 

In 1959-60, Bev Halstead (then Tarlo) described a new giant English pliosaurid
which he named _Stretosaurus macromerus_ - a huge animal that reached 15 m or
so (comparable with _Kronosaurus_), and you can find references to this animal
as the 'biggest marine reptile of all time'. Apparently there is a 3 m long
mandible from it - now, if that's accurate (I dunno where that jaw is), this
creature got bigger than _Kronosaurus_. It's now evident that _Stretosaurus_ is
a junior synonym of _Liopleurodon_ but it's still different enough for its own
species. I examined what _I think_ is the type of this taxon (_L. macromerus_)
in the Dorset Museum at Dorchester (thing is, the type is supposed to be at the
BM) - amazingly, it has had the end of its snout bitten off by another pliosaur!
This is apparently (so says Colin) common in big pliosaurs, and is also seen in
Indopacific crocs. I asked Dave Martill about this, and he hadn't heard of it
though, so I'm wavering as to whether it's an important thing to note. What the
hell.

Anyway, big liopleurodons may have been comparable with _Kronosaurus
queenslandicus_ at 14-15 m or so. Next on the scene (though, paradoxically, it
outdates all of these taxa in historical appearance) is a giant form from the
Late Jurassic of Wyoming - _Megalneusaurus rex_. This is only known from a few
bits of propodium (humerus fragments) but was allegedly huge and it's been
recently estimated that it was bigger than the others at 15 m+. It was mentioned
by Gilbert White in his writings on _Kronosaurus_ (in the 1930s) and was named
and described by Knight round about the turn of the century (1898-1902, and in
_Science_). The material has apparently gone missing - Ken Carpenter was trying
to find it at one point - but now Bakker is saying that he has it and is working
on restoring the creature. This is odd, and I'm not sure if it's anything more
than a rumour. Bakker published a huge paper on plesiosaur phylogeny in 1993 (in
which he named the new taxon _Attenborosaurus_), but didn't mention this beast.
So the jury's still out on this one.

Even if _Megalneusaurus_ is bigger than the other contenders, it is certainly
outclassed by the new King of the Mesozoic Seas, an Oxford Clay pliosaur known
from a vertebrae and other fragments (but are these of the same animal?). To
date, the only publication on this is an abstract in _Palaeontology Newsletter_
32 by McHenry, Martill, Cruickshank and Noe. They suggest that this animal was
16-20 m long and more than 50 tons in weight... comparable to a bull sperm
whale. Leslie Noe told me that this animal isn't deserving of a new name but on
Dave Martill's noticeboard a diagram of it is labelled as.... well, that'd be
telling. Dave said they'd be making a full-size robotic model of this beast but
I don't know if he was just pulling my leg, so to speak. 

Anyhow, despite some initial arguments over the identity of the vertebrae
(ironically, following a radio show in which Colin backed his view of it as
pliosaurian), the specimen now seem securely pliosaur. So if we have a 20 m
pliosaur, what's the limit on these things? Did they get as big as the big
baleen whales? 33 m and estimated weights between 130 and 200 tons for
_Balaenoptera musculus_. The latter name, incidentally, means 'Little mouse
whale'. Perhaps.

"Hello boys - how ya doing? Fun and games are afoot"

DARREN NAISH