GASTROLITHS & OTHER ASSORTED

[darren.naish@port.ac.uk]

Earlier today I wrote a long email about gastrolith 
distribution in theropods, its relevance for dinosaur biology, 
and loads of other stuff. Then the PC locked up and, to cut a 
long story short, all was lost. Hooray for computers.

Anyway, tis I, post-therapy reformation.

As Dave Varricchio noted in his paper on tyrannosaurid 
stomach contents, popular views about the distribution and 
use of gastroliths in dinosaurs need to be revised (so this is 
preaching to the largely converted, and most of this has 
been discussed on DML before anyway). The fact that 
gastroliths are present in _Lourinhanosaurus_, 
_Poekilopleuron_, _Baryonyx_ and a tyrannosaurid 
demonstrate that gastroliths are not unique to herbivorous 
dinosaurs. _Protorosaurus_ and aberrant stomach contents 
aside*, I think the possibility that these theropod taxa were 
herbivorous is rather unlikely, and given that non-
herbivorous extant birds also use gastroliths, their presence 
does not = herbivory. This is interesting in view of what 
some of us have been saying about possible omnivory in 
psittacosaurs etc.

*'Anatomy is not destiny'

Gardner et al's suggestion that presence of gastroliths in 
_Caudipteryx_ indicates myrmecophagy (based on 
comparison with pangolins, aardwolves etc which swallow 
sand/grit) is faulty because it's clear that non-
myrmecophagous taxa also have gastroliths. Plus, clear to 
anyone if they've been following the discussion about ant-
/termite-eating in alvarezsaurids is that myrmecophagous 
species have a bunch of skeletal specialisations not seen in 
non-myrmecophages, and these aren't present in 
caudipterids. The flip side is that the presence of 
myrmecophagous specialisations do not consign their owner 
just to a diet of ants/termites seeing as _Myrmecophaga_ 
can eat catfood and _Dasypus_ is a generalist in parts of its 
range. Now if only Nick Longrich would publish that 
bloody paper:)

Here are some rumours that may be of interest to some. 
Some more dinosaurologically oriented than others...

-- Some time around May 18th the Australian Museum is 
apparently set to host a press conference at which they will 
unveil some news regarding thylacines. Understandably 
rumours are flying round that a live/recently dead/cloned (!) 
one has turned up.. we'll see.

-- A megamouth shark washed up on the coast of South 
Africa some time within the last two weeks. This must be # 
14 or so, and I think it's the 4th specimen from the Atlantic.

-- We have what appears to be a new genus of tapejarid with 
a(nother) novel crest morphology here at UOP.

-- W. H. Bensted's notebook has recently been obtained by 
Maidstone Museum: sigh, more revisionist history on 
Mantell/_Iguanodon_ to deal with... seriously, Martin 
Simpson and I are working on this at the moment. It is 
looking like pretty much everything written about Mantell 
and the early discovery of _Iguanodon_ is in some way 
wrong. Certainly Bensted's contribution to the history of the 
'Mantel piece' is going to be substantially revised.

-- A new small theropod specimen has been discovered on 
the Isle of Wight and is being hailed as a possible 
_Calamosaurus_. It appears not to overlap with the holotype 
of this taxon though (cervical vertebrae) so this is not 
demonstrable. Is being kept at the Dinosaur Farm Museum, 
though don't know what they're doing with it.

-- Sadly I was unable to announce on DML the Crystal 
Palace Seminar which took place on Jan 4th this year. 
Speakers included David Norman, Deborah Cadbury and 
Hugh Torrens. The grounds of Crystal Palace have had a 
major revamping and the models have been restored and 
repaired. The two lost pterodactyls (apparently destroyed 
while the site was an army barracks) are now back in their 
rightful place and the water level has been lowered so that 
the ichthyosaurs, plesiosaurs and teleosaurs can be seen in 
their entireity. I was shown a photo last week which 
revealed that, to my surprise, the phalanges are visible on 
the outside (dorsal/external surface) of the ichthyosaur 
flippers. I think the idea here is to represent these bones as 
if seen in x-ray, much as the sclerotic ossicles are also 
visible on the outside of the eyeballs. This may have been a 
common technique used at this time as on Monday I was 
shown a cast Loggerhead turtle juvenile where the same 
thing has been done, viz, the phalanges were shown in relief 
on the outside of the flippers. Crystal Palace is also having 
various of the never-completed models made from the 
original plans. These include snakes, a mammoth, moa, a 
dodo and assorted cats and camels etc. My response on 
hearing all of this was "Gosh", or words to that effect (to 
paraphrase Trevor Beebee).

I noted a brief discussion on the list about sprawling posture 
in monotremes. Try these refs...

Lewis, O. J. 1963. The monotreme cruro-pedal flexor 
musculature. _Journal of Anatomy_ 97, 55-63.

Jenkins, F. A. 1970. Limb movements in a monotreme 
(_Tachyglossus aculeatus_): a cineradiographic analysis. 
_Science_ 168, 1473-1475.

Jenkins, F. A. 1973. The functional anatomy and evolution 
of the mammalian humero-ulnar articulation. _The 
American Journal of Anatomy_ 137, 281-298.

Pridmore, P. A. 1985. Terrestrial locomotion in monotremes 
(Mammalia: Monotremata). _Journal of Zoology_ 205, 53-
73.

There is more recent stuff but don't have it to hand. 
Basically, monotremes do 'sprawl' but not in the same 
fashion as lepidosaurs (contra Bakker and lots of other 
workers) and it seems that this was true of most basal 
mammals (or mammaliaforms). Recent papers by Luo et al 
and Sereno and McKenna on symmetrodonts and 
multituberculates cover this argument in detail - there is 
some controversy.

Darren Naish
School of Earth & Environmental Sciences
University of Portsmouth
Burnaby Building
Burnaby Road                           email: 
darren.naish@port.ac.uk
Portsmouth UK                          tel: 023 92846045                   
PO1 3QL                                www.palaeobiology.co.uk