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SAUROPOD EGGS AND DISH
[Is Jerry still at Southern Methodist?]
I have recently heard from Luis Rey that a vast new 'egg field' of probable
sauropod eggs has been unearthed in Spain. The size of several soccer pitches,
it is apparently being looked after by the National Guard or something.. Could
it possibly be an actual sauropod nest site?
DISH (Diffuse Idiopathic Skeletal Hyperostosis)
I haven't heard much recently about consistent pathological structures in
sauropod tails, and wonder what others make of them. First of all, does the
variety of sauropods in which they occur relate to the behaviour that caused
them (if, that is, they _are_ pathological and caused by action that results in
skeletal hyperostosis)? For example, diplodocids (sensu lato) possess damaged
verts in pretty much the same point (something like 17th cervical?), and I'm
guessing that this could correspond to the point where the tail would be bent
when rearing. The same could be true for euhelopodids, couldn't it? (Having
seen the photos in AA, it does appear as if verts got damaged where they were
pressed against others at the 'bend' point of the tail). Yet _Camarasaurus_
apparently also possesses such a condition at a similar point in the tail. Is
anybody aware of the condition being reported in any other sauropods?
[What was Jenson's case for rearing in _Cathetosaurus_, and does it still hold
if that dinosaur is 'sunk' into _Camarasaurus_?]
Now, distribution of skeletal hyperostosis amongst the species in which it is
known is not universal - has it been, or can it be, correlated with sex of the
individual? The most popular hypothesis I hear is that females had a specially
fused region of tail vertebra to aid them in arching it out of the way when
mating. But, supposing a DISH-sex relationship couldn't be proved, could such
pathologies only occur when animals had been consistent rearers? I entertain it
as a possibility than not all individuals within a species will behave to fulfil
all of their abilities (works for humans). There must be many elephants, for
example, than go their whole lives without ever adopting a bipedal stance, even
though they can. Likewise, amongst sauropods, some individuals might have learnt
that rearing was profitable and possible, whereas others just never took up the
habit. This could occur amongst a single population, where some individuals were
'braver' in this regard than others, or it could be uniformly restricted to
various sub-pops, where all individuals learnt to rear off peers and relatives.
Remotely, it could be a hereditary gene-linked habit.. but that's speculation.
So, is DISH found throughout single populations (i.e. pops. of fossils -
reconstructing the living population is a _little_ more difficult). Is it
pathological, or can this not be proved? Is it restricted to species consistent
with a bipedal/tripodal habit (camarasaurs may well have reared, but would they
use their tails to do so?)? If not, might it be related to other types of
behaviour that could cause this kind of pathology (_if_ it is pathology).
How do you prove that something in a fossil is pathological anyway?
I'm also wondering how profitable rearing would be in 'short necked'
dicraeosaurids. Their reach would be roughly similar to that of a camarasaur
(about 6 metres I seem to remember), but the two could still operate non-
competitively due to different feeding strategies. [Is there any possible
_Dicraeosaurus_ material from the Morrison?]
"Staring at the static on my TV screen"