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Hi Jon, thanks for your thoughts on iguanodontian
systematics (am ccing this to DML).
Re: your suggestion that _I. atherfieldensis_ and _I.
bernissartensis_ might be growth phases of the same
species, this is interesting and thanks for the data but right
now I find it very hard to believe: the two species aren't just
different in the features you state (hand and vertebral
proportions, forelimb ratios, manual phalangeal counts,
intersternal ossifications) but in others that seem less logical
in terms of ontogeny. For example, they differ in number of
caudal vertebrae (45 in _I. atherfieldensis_, over 50 in _I.
bernissartensis_) and the shape of the quadrate (pillar-like
in _I. bernissartensis_, curving in _I. atherfieldensis_).
Also, it would be nice to have the figures for this but surely
there are some _I. atherfieldensis_ individuals that overlap
in size with some _I. bernissartensis_ individuals, plus there
are (to my knowledge) no specimens that are intermediate.
Sorry to pull in anecdotal evidence, but fragmentary bits
(MIWG/IWCMS metatarsi) indicate there also seem to be
gracile _I. atherfieldensis_ that reached the size of a big _I.
bernissartensis_. It also seems unlikely to me that the
diagnostic dorsoventrally deep plate-like prepubic proc. of
the pubis in _I. atherfieldensis_ could ontogenize (new
word) into the shallower, more prong-like process of _I.
bernissartensis_. However, I see that your theory is a new
idea based on your work on hadrosaurs: hopefully this will
prompt someone in future to look into it in more depth.
Incidentally, one should not talk of 'crown' hadrosaurs
seeing as, by definition, crown groups only encompass
extant representatives of clades. A common error (the most
notorious of which might be Sullivan's 'crown-group
Actually, I. atherfieldensis comes out closer to haddies...
just as juvenile chimps might code closer to humans in a
They probably wouldn't seeing as the _Homo_-like
characters of baby chimps (proportionally larger cranium,
smooth brow ridges, flatter face) are not seen in hominins
closer to _Homo_ than to _Pan_. Baby chimps instead have
the intermembral indeces, palatal shape, long dentary
symphysis, dorsoventrally long ilia, opposable hallux and
laterally round (rather than oval) femoral condyles of non-
hominin hominids so surely would group close to _Pan_
even if coded as a separate OTU.
Much as I hate genera, hate generic proliferation, and
thoroughly despise monotypic "higher" taxa, my vote is for
Hmm, well it's by no means clear that Mantell's teeth were
from _I. atherfieldensis_, so this might not be so cool:)
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