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RE: Archaeopteryx London specimen made neotype by ICZN




--- Jaime Headden <qi_leong@hotmail.com> schrieb am Do, 27.10.2011:

> Von: Jaime Headden <qi_leong@hotmail.com>
> Betreff: RE: Archaeopteryx London specimen made neotype by ICZN
> An: "David Marjanovic" <david.marjanovic@gmx.at>, 
> Dinosaur.Mailing.List@listproc.usc.edu
> Datum: Donnerstag, 27. Oktober, 2011 06:19 Uhr
> 
>   I don't think the nature of "speaking German" has a
> thing to do with it. This confusion has persisted regardless
> of apparent "clear designation" of what von Meyer meant.
> They are still trying to piece out what is _meant_ and what
> is _inferred_, given the craptascular lack of specifics in
> the paper, but what is there is illuminating:
> 
> "As a supplement to my letter from the 15th of last month I
> can now tell you that I have studied the feather from
> Solenhofen from all angles, and thereby I arrived at the
> conclusion that it is a true fossil from the lithographic
> slate and that it agrees completely with a bird’s feather.
> At the same time I received news from Obergerichtsrat [a
> rank in the judiciary] Witte that an almost complete
> skeleton of an animal covered in feathers had been found in
> the lithographic slate. It shows several deviations from our
> living birds. The feather which I studied I will publish
> with an exact illustration. For the denomination of the
> animal I consider the term Archaeopteryx lithographica as
> appropriate’."
> -- von Meyer, 1861, as translated by Kodolsky, 2007: 
> http://iczn.org/content/comment-proposed-conservation-usage-archaeopteryx-lithographica-von-meyer-1861-aves-designa-0
> 
>   In this, I think Kodolsky has the right of it, and notes
> the extensive ambiguities including but not limited to the
> editors' personally-written title of the letter written by
> von Meyer, and the absolute lack of any reference to the
> principles of the body fossil in the body of his work. It
> would not actually matter if, later, von Meyer were to argue
> me _meant_ the feather to be the fixed type.
> 
> "Already from the simple middle foot can be concluded that
> this animal does not belong to the Pterodactyls, and the
> formation of the tail opposes the notion which we have of
> birds; and yet the feathers cannot be distinguished from
> those of birds. The fossil feather presented by me may come
> from a similar animal, for which I have chosen the
> denomination Archaeopteryx lithographica (Jahrb. für
> Mineral., 1861, p. 679)."
> -- von Meyer, 1862, as translated by Kodolsky, 2007
> (ibid.).
> 
>   Note the object to which the phrase "for which I have
> chosen the denomination" is the feather, not the "similar
> animal."

Yeah, that basically wraps it up. When the nomen was established, there was 
still only one specimen to which it could be applied. The second was known by 
hearsay only. Suppose it had been *another* feathered theropod species - by now 
we know it *could* have been.

>From von Meyer's tone, it's obvious he expected feather and skeleton to be 
>from the same animal. He may have been right, but that was not a certain 
>outcome in 1861, and it is not *that* clear even now.

Knowing what we do know now about feather evolution in theropods, any nomen 
attached to the feather would be a nomen dubium.

Glad to see this case finally closed. BTW the holotype is probably a subadult, 
being somewhat smaller than the Berlin one and markedly smaller than 
_"Wellnhoferia"_. All the material (except _"Wellnhoferia"_ and perhaps the 
Berlin and Haarlem specimens) seems to be immature. 
That's interesting, because we have to assume that the actual habitat was not 
the islands but the adjacent larger landmass: the lineage must have gotten to 
the Solnhofen lagoon area somehow, and certainly they did not arrive from the 
open sea...
So it seems that an above-average proportion of immatures ended up in the 
water. Possibly the volancy (not the technical flight capability, but the 
extent to what the aminals used it) declined towards maturity, with adults 
flying less often and less far than they *physically* could have - i.e. they 
had learned their limits and knew better than to take off in strong land winds? 
The other way around, those individuals *least* likely to end up in the fossil 
record were those that *did't* push their flight capability to the *physical* 
limit every time they could, but only did so when the weather was good. This 
capability, of course, increases as the individual gets older.

In any case, the taphonomic bias is remarkable. But in the absence of 
additional adults, we can only speculate. It may be chance. But if not, I 
suspect it's due to the fact that Archie's flight capability was not at all 
fully active, meaning it relied to a considerable extent on forces it could not 
control (i.e. the wind).*


Regards,

Eike

* There is a possibly related phenomenon I once saw in action. Pigeons usually 
travel in loose flocks. _Caloenas nicobarica_ arrange in a more linear group; 
small groups actually form a straight line sometimes. They breed on offshore 
islands and travel to the mainland to forage. These flights take place at dawn 
and dusk. The adults are dark grey, but the tail is brilliant white; it's 
incredibly conspicuous when they fly in a group in low light (it's actually the 
only conspicuous part of the animal under such conditions). The immatures OTOH 
are all dark.
As it seems, they use their "tail lights" to maintain flock cohesion. The 
immatures are then physically prevented from leading the group in flights over 
water. Considering that the "appropriate" (non-risky) migration behavior in 
birds is partially a learned trait, it's easy to see how natural selection can 
maintain the dark-tailedness of immatures.