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On the neural spines of _Amargasaurus_ and other sauropods, Brian
> I would expect near-perfect bilateral symmetry in the living animal,
> no? If the spines are not straight or parallel, that would indeed
> seem to indicate to me distortion after death and fossilization. Can
> anyone supply a reason to think otherwise?
Can't really answer Brian's question but...
Hiccups in bilateral symmetry are of course not uncommon and
fusions, morphologies of processes, and such things as pleurocoels
and foraminae are not infrequently asymmetrical. I have seen strings
of vertebrae where the bones are fully fused up on one side, but not
on the other (in some birds, this may be due to viral infection -
P. Davis pers. comm.). And there is a very interesting little
dinosaur specimen, currently in press, that has some bearing on this
Given the incidence of pathology and breakage in the spines of living
animals that have tall neural spines (obviously I have no statistics
on this, but am going from what I have seen in diagrams, photos and
specimens), we might predict high-spined dinosaurs with bifurcating
spines to often be asymmetrical. Also, some high-spined dinosaurs are
famous for having damaged spines. _Becklespinax_ exhibits what
appears to be severe vertebral trauma and Stromer's figures of
_Spinosaurus_ have neural spines that are not straight in cranial
view, but wiggle from side to side. Though this has been generally
assumed to represent post-burial deformation, is this really
definitely the case? Don't know.
"Crocodiles are in no way a relictual or degenerate group"
Carve this into your desks and foreheads