[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
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
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
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