Re: Archaeopteryx not the first bird, is the earliest known (powered) flying dinosaur

["Jaime A. Headden" <qilongia@yahoo.com>]

Greg Paul (GSP1954@aol.com) wrote:

<I just penciled out a detailed restoration of the skeleton on the type
Microraptor gui (which I suspect is the same as the type species unless the two
are from different stratigraphic levels).>

  There seems to be a dearth of evidence that declares that a stratigraphic
difference between specimens has any bearing on the speciation issue. It has
been used to separate taxa, but the prevalence of the same species spanning
entire epochs would be an argument against this principle of stratigraphic
speciation. Furthermore, I see no reason how a stratigraphic separation
separates species.

<There is no justification for the narrow inner wings restored on the initial
protoglider restorations. The forewing alone has an area/total mass ratio that
falls in the middle of the avian range and is similar to that of Archaeopteryx,
the hindwing halves the wing loading of course. The leg wing is so well
developed that suggestions it was not frequently fully deployed as an airfoil
are not credible (it would be a plausible display device only if there were no
highly asymmetrical feathers), There is no viable means to deploy any part of
the leg feathers with the legs even partly folded (all such suggested
arrangements are awkward and contrived at best, if not anatomically
improbable).>

  Paul (2003) in _Prehistoric Times_ and Xu et al. (2004) in _Nature_ restored
the proximal leg feathers and the proximal (humeral, aka, tertial) feathers
based largely on the asusmption that these feathers existed, rather than from
any actual extrapolation from the fossils, as these taxa lack these preserved
structures. In *Sinornihosaurus*, the type lacks feathers. NGMC 91 only
preserves thigh feathers, an issue as yet unaddressed, and lacks tarsal
feathers and it is unlikely they existed. Some would lump *Sinornithosaurus*,
NGMC 91, and *Microraptor* into a single genus (using other claims of generic
and species separation based on similar arbitrary descisions of splitting or
lumping, so it seems odd to use one to justify the other when objectivity in
either is lacking), and this would attempt to place the thigh structures in
NGMC 91 (despite their distal lack) onto the thighs of *Microraptor* (which do
not preserve thigh feathers) and would thus use this to infer the shape,
length, and thus area, of the thigh wings. The same goes for the tertials
lacking, yet restored, in these taxa as for *Archaeopteryx*. So isn't it a
very, very broad assumption to describe the area of missing feathers in these
animals?

<Gliders are passive aerialists and do not need to updgrade their flight
apparatus beyond the limits seen in modern exampels, none of which is as well
adapted for flight as Archaeopteryx much less dromaeosaurs.>

  Unless these gliders, in their attempts to steer themselves, had means to
further retard the time of falling to the ground or another aerial target
(prey? a branch?) if they, say, _did something_ else, and perhaps selection
acts on this physical capabilities, developing, perhaps, a different drag
apparatus and lift-producing features? A flight stroke, already present perhaps
(based on ancestry?), based on the predatory stroke.

<Basal dromaeosaurs were arm powered fliers of some sort, with the leg wing
acting as some sort of nonflapping airfoil.>

  I would not be so dramatically endorsing of this, as the hindwings seem
largely adapted in a single group of dromaeosaurids that appear to have shared
their own common ancestor separate from that of larger dromaeosaurids. Thus
they are optimally parsimonious (indeed, _logically_ so) as autapomorphies of
the Microraptoria (sensu Senter). The other dromaeosaurids, including perhaps
also *Bambiraptor* (synonym of *Saurornitholestes*?) show clearly basal states
that prolong their terrestrial natures to basal troodontids and earlier as
ancestral, which microraptors elaborated. The prescence of long tarsal feathers
in *Archaeopteryx* do not appear to form a definite vane, while those of the
wings of the same specimens would preclude if a vane was present, it should
logically preserve as such.

<Whether their flight will ever be well understood is open to question, since
their flight apparatus was so radically different from anything present today.>

  Yet we can argue that features are indeed related to flight?

<The notion that the flightless dromaeosaurs of the Cretaceous were not
neoflightless descendents of flying dromaeosaurs more advanced than
Archaeopteryx is highly illogical since, as I explained in detail in DA, they
possess a host of flight characters more derived than those of Archaeopteryx
(and similar to those found in modern flightless birds).>

  This might be logical if we were operating under the assumption that all
features birds use to fly with are indeed related to flight explicitly, rather
than adaptable for flight, along with other osteological features.

  Cheers,

Jaime A. Headden

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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