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Re: Effigia [was Defending Photoshop]




"Jaime A. Headden" wrote:

> David Peters (davidrpeters@earthlink.net) wrote:
>
> <The postfrontal is probably present. Two identical ?cracks? suggest so. They
> extend almost to the prefrontals.>
>
>   The authors do not contend the animal is not a crurotarsan, so the presence
> or lack of prefrontals is immaterial to their study. However, we are also
> fortunate that the illustrations were made with the fossils at hand and not
> through the benefit of an indecent photo for the purpose as the one in the
> figures. Indeed, how one could tell the cracks in the crushed skull from an
> array of associated circum-frontal bones versus a single, cracked frontal, I
> have no clue. Yet the authors show that there was a strongly interdigitating
> arrangement of the postorbital and frontal, and the lack of such a contact
> between prefrontal/lachrymal and the frontal/nasal. This surely is the result
> of examining the multitude of cracks and finding that a sinuous,
> interdigitating array of "cracks" probably represent a suture pattern.

I'm just posting a red flag. Something doesn't look as stated.

>
> <The postorbital portion of the skull is rounded posteriorly and appears to be
> rotated ventrally, so the upper temporal fenestrae open more posteriorly.
> Norrell and Nesbitt ?fixed? it in the recon. When left alone the jugal
> descends.>
>
>   The authors in their restoration gave a generalized idea of the arrangement.
> As in *Shuvosaurus*, however, the skull had a more "dinosaurian" arrangement
> and the postorbital's contact is not unusual at all ... for a dinosaur.

Nobody has done a reconstruction of Ticinosuchus since Krebs, And someone needs
to. It's not your typical rauisuchian.

> The
> jugal and quadratojugal are absent, but known in *Shuvosaurus*, and the
> position of the quadrate (based on the length and extent of the ptergoid and
> palatine to the interconnecting bones) is also based on *Shuvosaurus*. This
> means, as the authors state, the postorbital/squamosal contact is probably
> normal, and the occiput was rotated ventrally.

Just another red flag. Often WYSIWYG in fossils, 'repairs' (like making sure 
heavy
sauropod tails contact the groud) to the contrary.

>
>
> <In dorsal view the rostrum has a 90º divergence angle and the rami appear
> rather straight, but the reconstruction rounds it. Maybe the ventral view 
> shows
> this better.>
>
>   The skull has been dorsoventrally crushed. The restoration doesn't help in
> essentially keeping much of this distorted width. Nonetheless, the skull was
> likely a good deal narrower, and the shape of the ventral (tomial) margin of
> the premaxilla was curved as occurs when the two halves of the skull are
> rotated ventromedially into a more "perfect" arrangement. This is, of course,
> completely subjective, but there seems a bit of experience in examining
> distorted skulls to consider the reconstructive models.
>
> <Like Effigia, Ticinosuchus also has an enlarged orbit,>
>
>   An effect of the size of the skull, as in species of *Araripesuchus*.

As Al Franken used to say, "And that's... ok"

>
>
> <an offset femoral head,>
>
>   As do most bipeds.

Ticinosuchus was not a biped. Or can you show me that it was?

>

>   GSP even made a comparison of aetosaurid skulls with *Erlikosaurus*, with
> some interesting, and favorable interpretations. Unlikely given their nature 
> as
> maniraptoran theropods of a highly derived nature, but interesting 
> nonetheless.
> However, several other issues of the limb anatomy of any aetosaur shows that
> the forelimbs were heavily weight-bearing, the manus is not so much as tiny
> compared to the arm as it simply is to the foot. Nesbitt and Norell show that
> the manus is INCREDIBLY small compared to the forelimb itself, a feature one
> also sees in bipedal ricochetal mammals such as the grasshopper mouse or
> jerboas, in several hypsilophodontids (which are also notable for having a
> forelimb so completely smaller than the hindlimb, as in *Effigia* but not as 
> in
> aetosaurs), and that the forelimb and hindlimb design feature non-offset 
> capiti
> of the epipodials, a sprawling and not linear arrangement between epi- and
> propodials, etc.

The key thought here is that Ticinosuchus led to at least two branches now, the
bipeds and the armored ones, much as early dinosaurs led to theropods and
scuttellosaurs. So, it can happen. Try not to apply too many aeotosaur 
characters
to something that is not an aetosaur. Some characters, yes, but pick the correct
characters, before and after the split.

>
>
>   On the restoration, however, it is not possible to observe in the fossil the
> morphology of the mandible, so how much of this is real is unclear. Thus the
> "brevity of the dentary, length of the mandibular fenestra ... ascending
> retroarticular process" are not actually observable. In the latter feature,
> ascending is relative to the shape of the posterior mandible, while the length
> of the dentary is relative; how short is "brevity"? In aetosaurs, the dentary
> if 50% the mandibular length, this animal has one incredibly shorter, and
> *Shuvosaurus* doesn't clarify either the size or extent of the external
> mandibular fenestra OR length of the dentary. And reduced premaxillary teeth?
> This animal is _edentulous_, and thus does not share ANY feature of the
> dentition or dental arrangement with aetosaurs.

Same comments as above with the addition of: can you find ANY other taxa with a
dentary a brief or nearly so? And with a mandibular fenestra a extensive or 
nearly
so. We're just looking for a best match among candidates known to date.

>
>
> <Were armor plates or scutes found? I overlooked the note if so.>
>
>   They were not recovered, and given the fauna, armor plates tend to be found
> more than BONES are, so there is a good chance there were no scutes present.
> That same is true for most rauisuchians, including all other poposaurs.

And that's okay. After all, many dinosaur bipeds lost their ancestral scutes 
too.

>
>
> <To move Effigia closer to aetosaurs requires one more step. To move it to the
> base of the Ticinosuchus + aeotosaurs requires 5 more steps. To move it close
> to Lotosaurus requires 13 more steps. The clade Ticiniosuchus + aetosaurs is
> the sister to the Archosauria,which includes Turfanosuchus + (Dinosauria +
> Crocodylomorpha).>
>
>   This is only because you've reinterpreted *Lotosaurus* as a dinosaur.

No, PAUP nested it there based on discrete data points. And it's not a typical
dinosaur, Jaime. It's one of the cuzzins no one talks about.

> Given
> my comments on that when this issue came up, one should be very circumspect
> when non-dinosaurian vertebrae, non-dinosaurian scapulae, non-dinosaurian limb
> bones, all point to a non-dinosaurian but crurotarsan *Lotosaurus*. But go
> ahead and publish findings on detailed photos of the original material, if it
> passes peer-review. I suggest having Clark and Wu work as reviewers.

You need to do the phylogenetic analysis before saying such things, Jaime. Fight
facts with facts, not words. It doesn't matter if a few to many characters are
different than typical, it's the aggregate that counts. Parsimony, in other 
words.
Otherwise you're a follower of brother Larry Martin who says, "Show me one
character that is unmistakeably avian among theropods." And of course, one
character can always be found elsewhere, due to convergence, somewhere else.

re: Clark and Wu, It's out of my hands. But good suggestion.

>
>
> <Would have been interesting to see the strange mandibles, but they were only
> reconstructed. This also gives kudos to PAUP which identified a sister taxon
> relationship between two overall and at first glance unlikely sisters.>
>
>   Once again, PAUP has done nothing but applied YOUR subjective data to an
> algorithm.

Interesting statement considering you have not seen the data. Next are you going
to accuse me of having the devil's mark on a part of my body typically hidden 
from
view. Don't go there, Jaime. It's not good for you. Fight PAUP with PAUP.

> These programs used, PAUP or Photoshop, are simply tools, and have
> no value otherwise, nor any particular value in any result that does not
> distill down to the input data.

And you forgot to say: It's still a Newtonian universe.

David Peters

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