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Re: MORE ON BCF



Matthew Troutman wrote:
> 
> <<You know, I'm getting tried of this argument. You must know and
> relized that the fossil record is poor for the early to middle
> Jurassic.>>
> 
> I know that it is poor, but we cannot use that as some sort of
> scientific "cushion" to shield ourselves from the fact that we still
> have not found any unequivocal bird or dino/bird bones.
> 

Poor, POOR! It's down right pathic if you really look at it. We're (you,
me, Scientist) are trying to find out what these incridble animals
looked like, lived, and evolved on very little. Just look at a map of th
USA, plot out all the states that have the Morrison Formation and then
look at the rest of the USA, there's a LOT of missing data there. I
think what each of us should say is, for example, IMHO there were lots
of small theropods running around the early-late Jurassic, even though
there isn't any fossils to prove this, and YOU should say, IMHO this
isn't true, and be able to accept that and other ideas.

> <<And why is it, I've asked this on the list before, that if a skeletal
> element that might belong to an non-avian theropod OR an avian-theropod
> that it's always placed into the non-avian theropod? Case in point,
> Jensen & Padian, 1989, they're going over Jensen's 'birds' Palaeopteryx,
> the proximal tibia is refered to either a Deinonychosaur or BIRD, and
> BYU 2033, a right femur might be a Deinonychosaur or BIRD!, but everyone
> will say it's a Deinonychosaur. I say, lest get some balls here and say
> it's a BIRD (or avian-theropod, what ever)!!!>>
> 
> It still is not unequivocably known that they are birds or not. Paul
> (1988) has questioned the avian assignment.  Even if they are birds, SO
> WHAT?  Still, it is close enough to the Jurassic/Cretaceous boundry that
> it makes no real difference.

Gee, and the Jensen Padian paper was when? 1989. What difference does it
make, that they were more around at the time!

> 
> >There are Archaeoptryian teeth from the Kimmeridgian of Portugal.
> 
> I have not yet seen this paper, but what about the possibility that they
> are crocodilian?  Was this addressed?
>

Yes, read the paper.
 
> <<And what about ichnology? The forgotten science. There are thousands
> and thousands of small theoropod prints from the early Jurassic to the
> late Jurassic. With some early Jurassic prints that are so small they'll
> fit under a quater. What about the bird (or bird like prints?just forget
> them? Not good enough?)>>
> 
> Let me quote parts of Padian and Chiappe 1997 pertaining to this issue:
> 
> "Lockley et al. (1992) argue that there are some possible bird tracks in
> the fossil record as early as the late Early Jurassic (e.g.
> _Trisauropodiscus_ from Arizona and South Africa), but their criteria
> are somewhat vague, and have not been demonstrated as unique characters
> of bird tracks, or of certain taxa within birds (Chiappe, 1995a; Padian,
> 1997).  The degree of divarication of the second and fourth toes figures
> prominently in their discussions, but other morphological features of
> the tracks are not clearly diagnostic of Aves; the authors also
> acknowledge the problematic lack of skeletal evidence of birds until the
> Late Jurassic.  It is not clear that the authors are identifying these
> tracks as avian; they are noting presumably avian features.  Still,
> 'avian features' can only be either those of true birds of convergent
> features of other taxa (presumably, in this case, small non-avian
> theropods), so either way some intriguing questions and doubts are
> raised."  Padian and Chiappe 1997; p.14
>
But this doesn't mean they WEREN'T made by birds. We have ichnologist
and non ichnologist talking here.
 
> Molnar (1985) has questioned the birdiness of Ellenberger's South
> African tracks, saying that the "feather imprints" are actually
> invertebrate trails that trod over regular tracks.

And when was Molnar's paper written? Lockley et al, 1992!.

Tracy

OW! My head is starting to hurt!