[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
<<Troutman appears in part to be misunderstanding and misreading my
statements on indicators for preflight versus loss of flight in
It seems that I have to an extent.
<<I say that secondarily flightless birds have very short tails because
they are much shorter than those of the earliest known flying bird,
Not alvarezsaur tails! (And yes, they do appear to be birds because of
the loss of the postorbital-jugal contact and the loss of the
<<All flightless birds have larger sterna than the urvogel. I never said
that ossified sternal ribs are limited to flightless birds,
Archaeopteryx did not have them.>>
It is POSSIBLE that _Archaeopteryx_ had sternal ribs, an ossified
sternum was not found in any specimens until _A. bavarica_ was found.
The sternal ribs MAY have POSSIBLY been cartilageous. (Note that I
restrict myself from full advocacy).
<<Troutman's statement that all early birds have a sternum similar to
that of Archaeopteryx and Protarchaeopteryx is quite false,
Archaeopterygiform sterna are unique in their particular shape.>>
Actually, _Protarchaeopteryx_ does not have a similiar sternum to
_Archaeopteryx_ because _Protarchaeopteryx_ had paired sternal elements,
while _Archaeopteryx_ had a single sternal element.
<<The anterior indentation is not for the coracoids, it is on the
I must disagree here. From what I have seen (of _A. bavarica_), the
indentations on the _Archaeopteryx_ sternum are coracoidal facets.
<<Ratites have very small heads relative to their bodies, smaller than
in flying birds.>>
True, I don't know why I said that they large heads (maybe I was
thinking of them as compared to other bird skulls).
<<Troutman's insinuation that I need to look at more birds is misplaced.
I have gone through the Smithsonian's bird skeletal collection for the
last 20 years. I've examined the Archaeopteryx specimens. I have
measured kiwi sterna. I suggest Troutman examine more birds:)>>
I have been looking at birds all my life. Though I have not been to the
Smithsonian, I am well-versed on avian anatomy. I have seen an
_Archaeopteryx_ specimen (the best, _A. bavarica_) and I have seen kiwi
sterna (and I still say that they are 25% of the thoracic cavity).
Sorry if I have offended you somehow.
<<A running protoflier that is not as close to birds as Archaeopteryx
should bem less avian than the latter.>>
True. And from what I have seen, the _Protarchaeopteryx_ and
_Caudipteryx_ specimens are far less birdlike than _Archaeopteryx_. For
one, _Protarchaeopteryx_ still has paired sterna, serreated teeth,
unfused metatarsals and a non-reversed hallux. _Caudipteryx_ retains a
postorbital-jugal bar contact, as well as a quadratojugal-squamosal
contact, lacks any indication of prokinesis which probably was present
in (_Archaeopteryx_), non-reversed hallux and unfused metatarsals.
_Archaeopteryx_ LACKS postorbital-jugal contact, squamosal-quadratojugal
contact, any features that indicate at least incipent prokinesis,
serrated teeth, paired sterna, unfused metatarsals and a non-reversed
hallux. Now, if you are going to put _Caudipteryx_ and
_Protarchaeopteryx_ further up the avian family tree than
_Archaeopteryx_ you will have to account for the reversals of these
<<Ergo it should have a shorter tail, or the urvogel would have to
reevolve a long tail.>>
Maybe it was secondarily lost in _Caudipteryx_ and
<<The protoflier should have a smaller sternum without ossified sternal
ribs because it does not have flight muscles as large as the urvogel, or
an air-sac complex as well developed.>>
There is no indication of something like this. One can argue that
protofliers had stronger muscles, it makes little difference. Anyway,
it does not seem that they did have stronger flight muscles since the
pectoral girdle elements are smaller as well as the humeral crests. The
airsac stuff is rather meaningless too, _Archaeopteryx_ could just have
a secondarily small airsac complex, or the sternal ribs were unossified
or depended on suprapubic ventilation more so than its outgroups.
<<Since Caudipteryx has some better developed flight related features
than Archaeopteryx, of the same sort seen in flightless birds, it is
more probably a secondarily flightless form than a protoflier.>>
Read above. Your "flight characters" do not weigh in as much as the
other more important osteological characters.
Get Your Private, Free Email at http://www.hotmail.com