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RE: something's wrong here: Qianosuchus phylogeny



All I'm saying is "You can't get there from here," John.

As a positive-thinking scientist who wants to support the traditional tree, you 
could say, "It's simple: Here's how you derive Scleromochlus from the 
proterochampsids and pterosaurs from the scleromochlids." 

The problem in small studies is PAUP delivers "by default" nestings if the 
taxon list is restricted, as it is here. Larger surveys show the traditional 
list and nestings are erroneous. And speaking of larger surveys, Hill 2005 is 
full of errors.

Show me the better way. I can show you, if you can't show me.

DP



-----Original Message-----
>From: John Scanlon <riversleigh@outbackatisa.com.au>
>Sent: Sep 2, 2007 9:15 PM
>To: 'david peters' <davidrpeters@earthlink.net>, dinosaur@usc.edu
>Subject: RE: something's wrong here: Qianosuchus phylogeny
>
>There you go again, talking in terms of deriving clades or terminal taxa
>from other terminal taxa. That's not what PAUP is about, it's not what
>phylogenetic analysis is about, it's not what we'd expect to see in the
>fossil record. That's what's wrong here: the bogosity is mostly in your way
>of thinking.
>
> 
>-----------------------------------------------
>Dr John D. Scanlon, FCD
>Palaeontologist, 
>Riversleigh Fossil Centre, Outback at Isa
>19 Marian Street / PO Box 1094
>Mount Isa  QLD  4825
>AUSTRALIA
>Ph:   07 4749 1555
>Fax: 07 4743 6296
>Email: riversleigh@outbackatisa.com.au
>http://tinyurl.com/f2rby
>
>
>> -----Original Message-----
>> From: david peters [mailto:davidrpeters@earthlink.net]
>> Sent: Saturday, September 01, 2007 5:09 AM
>> To: dinosaur@usc.edu
>> Subject: something's wrong here: Qianosuchus phylogeny
>> 
>> Thanks to Matt Celeskey, I now have the pdf of the Qianosuchus article. So
>> Fabio, if you're still interested, I can send you a copy.
>> 
>> The strict consensus tree in the accompanying pdf file looks
>> 'traditional.' By that I also mean 'bogus' as many of you already know.
>> Let's start the rant right here:
>> 
>> Hyperodapedon
>> Prolacerta
>> Erythrosuchus
>> Euparkeria
>> Proterochampsidae
>>      Scleromochlus
>>           Pterosauria
>>           Lagerpeton
>>           Marasuchus
>>           Ornithischia
>>           Sauropodomorpha
>>           Herrerasaurus
>>           Theropoda
>>      Ornithosuchidae
>>      Qianosuchus
>>      Phytosauridae
>>           Gracilisuchus
>>      Postosuchus
>>           Crocodylomorpha
>>      Stagonolepidae
>>           Fasolasuchus
>>                Ticinosuchus
>>                Prestosuchus
>>                Saurosuchus
>> 
>> 
>> Prolacerta > Proterosuchus > Erythrosuchus > Euparkeria is all just fine.
>> Then the trouble really starts.
>> 
>> Can anyone tell me how you derive Proterochampsidae from Euparkeria?
>> That's quite traditional in many trees. But it's so wrong. Can't we find
>> any other taxa to fill this gap? What about Vjushkovia?
>> 
>> Then, can anyone tell me how you derive the so-called 'Crurotarsi' from
>> Proterochampidae? Phytosauridae, yes. But say no to Stagonolepidae,
>> Gracilisuchus, Rauisuchidae, crocs and the rest. Look above the ankles!
>> Look at the nares!
>> 
>> Also arising out of Proterochampsidae: Scleromochlus! What??? Put those
>> two side-by-side in a PowerPoint presentation and listen for the giggles.
>> They almost could not be more different.
>> 
>> But wait, it gets worse: Pterosaurs arise from Scleromochlus and its
>> unknown sister taxa!!! Suddenly the smallest hands in all creation become
>> the largest! And that stub of a metatarsal 5 becomes a highly specialized
>> retractable toe??? Bogus. I know, I know, we're talking about sister taxa
>> here, but you have to go pretty far back in this family tree to get that
>> toe to grow back.
>> 
>> Then Lagerpeton arises from the sister to pterosaurs? I don't think so.
>> It's closer to Tropidosuchus and then Chanaresuchus and then
>> Proterochampsa. So we skipped a generation. And toe five is gone again.
>> 
>> Out of Lagerpeton arises Marasuchus, even though the hips and toes don't
>> match. Now it would be good if Marasuchus could arise from a sister to
>> Scleromochlus, with which it shares so much more. Again, we skipped a
>> generation.
>> 
>> Last but not least, theropods arising out of sauropods and ornithischia?
>> Shouldn't that be the other way around? Aren't theropods closer to
>> Marasuchus in every way? Sharp teeth, reduction of digits, etc. By the
>> way, toe five makes a return in some of the above.
>> 
>> No wonder the authors were not able to figure out where Qianosuchus
>> nested. They needed the following taxa: Triassolestes, Turfanosuchus,
>> Pseudhesperosuchus. They need updates to Ticinosuchus. They also need more
>> characters. That dorsal nose in Q. is very much like what is seen in
>> aetosaurs, by the way, which are also derived from Ticinosuchus. So, not
>> sure if that tall slender tail of Qianosuchus is swimming. Especially
>> considering that the transverse processes that would have anchored the
>> tail rectractors are really hard to find.
>> 
>> The world view of traditional workers is that someday some series of taxa
>> will fill in those currently untenable gaps in the evolution of one form
>> into another. There's a simpler solution. It's called parsimony. We have
>> enough taxa to make it work so that sister taxa seem to blend into one
>> another morphologically, but they must be used. And when all the work is
>> done, you have to step back, take a look at the whole thing and ask
>> yourself: "Does this make sense?" remembering that evolution works in tiny
>> increments.
>> 
>> Last rant: specimen-based studies: good. Suprageneric-based studies: bad,
>> as shown above.
>> 
>> David Peters
>> St. Louis
>> 
>> 
>> 
>> 
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