>Hi all,
>Like fellow member HP Dinorampage, I've
got some questions to and I hope if someone can help me
>out with the
following:
>1) Ginnareemimus
---WHEEP WHEEP
WHEEP--- "Non-valid informal name alert" ----WHEEP WHEEP
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>is reported to have an almost
"arctometatarsalian" pes, like in Sinovenator, but how does
> this relate in terms of their
relationships, are they closely related or does this mean the
>arctometatarsalian
> pes can be
achieved by convergence leaving it as practicly meaningless in
phyletics?
Okay, a few
things:
A) The Thai
ornithomimosaur actually has a metatarsus which is closer in form to
ornithomimids proper than is Garudimimus.
Sinovenator's pes, on the other hand, is
non-arctometatarsalian.
B) Almost all recent
studies ally troodontids with dromaeosaurids and birds rather than with
ornithomimosaurs, so the arctometatarsus is clearly convergent between these
groups.
C) Convergence per se
does not render a character invalid; after all, "loss of teeth" is a perfectly
good synapomorphy for oviraptoroids and a perfectly good synapomorphy for
higher ornithomimids and a perfectly good synapomorphy for modern birds, even
if it convergence between the three groups.
>2) Another Ornithomimid question: after
looking at some figures of the redescription of
>Archaeornithomimus in
> a JVP-issue
(can't remember the volume anymore) and reconstructing it's pelvic girdle +
hindlimbs,
> something came up
along the way which was also quite suspect in the figures: the pubis, at
>least it's distal
> end is somewhat
recurved, giving the impression of an opisthopubic state of the pelvis. Is
this
>another clue
> of the
Ornithomimids being related to an Archaeopteryx or an animal close to
this?
Not
really. The rest of the anatomy is pretty clear that ornithomimids
branched off prior to an oviraptorosaur-dromaeosaur-bird division.
Furthermore, when put into articulation, it is hardly "opisthopubic", any more
than (say) Coelophysis is.
>3) Again on Archaeornithomimus and the
supposed synonymy to Garudamimus, what are the shared
> characteristics
between the two apart from shape of the pubis and are there any differences
>between
> them? The femur
for instance is practicly straight in A. while it is curved in G. and the
crest on the
>
tibia
> (damn' names...)
on it's proximal end is less pronounced in A. compared to G., but there are
more
>
right?
Actually, the
problem is more that SOME of the Archaeornithomimus material might
belong to Garudimimus, not that the two are necessarily complete
synonyms.
>4) Is Confuciusornis dui still considered a valid
species of Confuciusornis?
I'll get out my
species-ometer and check. --whoop whoop whoop--, Ah, well,
inconclusive... :-)
Seriously, though,
there are not absolutely clear answers to questions of this sort. I
suppose some people do consider it valid.
>5) If so,
what is it supposed lifestyle with the upward curving horny sheat at the tip
of the beak? It is somewhat
> similair in
structure to the beak in Rhamphorhynchus for example, which probably pierced
it's prey (most of
> the time fish) while
skimming the waters. Is this practice reasonable and is it appliable to C.
dui? And what
> are the supposed
life-style for the other Confuciusornithes Confuciusornis, Longchengornis
and
> Changchengornis?
Sounds like a research
project to me... In fact, I don't recall anyone doing much serious work
on the paleobiology of these early birds (other than climbing ability).
Folks, research takes TIME, and the folks from China and their co-authors have
been damned busy just describing the wealth of material!
>6)
Changchengornis is smaller than Confuciusornis by almost a third IIRC and in
extant mammals, the predator
> is smaller than
it's prey (some examples can be thought of such as the great white shark),
Now, WHOA there
partner!! There is no such pattern (for mammals, which really doesn't
have any bearing on birds anyway). After all, the main prey of foxes or
bobcats or moles or maned wolves or pinnipeds or bats or etc. is often much,
much smaller than the predator itself. Furthermore, it has not been
established that confuciusornithids are carnivores or insectivores or
frugivores or granivores or piscivores or whatever.
>does
this
> indirectly mean
that Changchengornis was more predatorial based the other
Confuciornithes?
?!?!?! A very
odd approach. It is like saying "European hares are smaller than
American jackrabbits. Is this indirect evidence that European hares are
more predatorial than jackrabbits?".
> The
hooked
> beak can be seen
as another clue for it's predatorial lifestyle, but apart from
that.
See above as to lack
of any serious work on the diet of these early birds.
>7) Is a
vulcanic eruption the cause of the major faunal death in the Lianoning basin
or are there other theories
> as well?
A serious taphonomic
study of these beds have yet to be attempted. I will point out that
although the sediment is believed by many to be volcanoclastic, that doesn't
mean that the faunal assemblage therein must necessarily be victims of the
various blasts. They may simply be accumulating into these bodies of
waters by ordinary attrition, but the bottom mud happens to be volcanoclastic.
(That being said, there is preliminary evidence that at least some horizons in
there might be mass kills: Confusciusornis bone beds, for
example).
Also, one can get very
similar types of preservation in environments where volcanic episodes are not
invoked: the Green River Shale of the Eocence of North America stands as a
good example.
>9) In DA HP
Greg Paul states that Eoenanthiornis could be a juvenile or subadult genus, is
this correct?
We'll have to wait and
see if others accept his argument.