Lü and Li 2006, a review

[David Peters <davidrpeters@earthlink.net>]

Bruno Campos was kind enough to send me a pdf of the recent paper by  
Lü and Li (2006), Preliminary Results of a Phylogenetic Analysis of  
the Pterosaurs from Western Liaoning and Surrounding Areas, J.  
Paleont. Soc. Korea 22: 239-261.

The aim of the paper was to explore the interrelationships of most  
Liaoning pterosaurs conducted using a modified character matrix of  
Kellner (2004). The matrix contained 80 characters and 56 taxa with 3  
outgroup taxa (Ornithosuchus, Herrerasaurus and Scleromochlus).

1. Well, the choice of the outgroup taxa dooms the base of this study  
from the start. Pterosaurs are lizards, not archosaurs as shown by a  
cladistic analysis 2 to 14 times larger and more inclusive than any  
prior attempt at classifying amniotes.

2. 34,000 most parsimonious trees were found and that's because the  
limit of the Max Tree was set at 34,000. Wow. That should be a huge  
red flag that something is rotten in this tree and more work needs to  
be done.

3. As usual, the highly derived pterosaur, Rhamphorhynchus, is shown  
to be the sister group to the classic 'Pterodactyloidea' when anyone  
with an eyeball would be hard-pressed to find a synopomorphy or two  
uniting the two. In an unpublished cladistic analysis of greater  
breadth, Rhamporhynchus is a highly derived dead end leaving no  
progeny and the pterodactyloid grade arises four times by convergence  
from dorygnathids twice and via basal dorygnathids, from  
scaphognathids twice.

4. The clade containing Azhdarcho and Eopteranodon continues getting  
mixed up with the clade containing Quetzalcoatlus due the convergent  
presence of hyperelongated cervicals. This is also the source of the  
confusion regarding the putatitive relationship between  
Quetzalcoatlus and Tupuxuara.

5. No tiny pterosaurs (typically known from numbers rather than  
names) were included, which also screws up the results royally.  
Tracings of pterosaurs in eggs show that their proportions do not  
differ greatly from their parents, so any so-called assignments of  
short-rostrum 'juveniles' to long-rostrum 'adults' are false and  
misleading.

Bottom line: garbage in, garbage out. Pretty much a useless analysis  
that sheds little light on pterosaur relationships.

Pterosaur workers: Get rid of your gender bias! Use more Dorygnathus  
and Scaphognathus specimens. Use more characters. Otherwise you, too,  
will be stuck with 34,000 MPTs.

Alas.

David Peters
St. Louis