re: paper on drepanosaurids + woven bone ps

[david peters <davidrpeters@earthlink.net>]

Wonder how Senter pulled Longisquama out of Protorosauria (=Prolacertiformes)? 
It seemed pretty locked in. But if only Tanystropheus was looked at then 
there's a problem...

Also wonder if Senter found the antorbital fenestra in drepansaurids. 

At first glance the other problem with this phylogeny would be too few taxa. 
Humans can be lumped with rats if you don't include any other mammals in an 
analysis. In like fashion, including Boreopricea, Jesairosaurus, Cosesaurus and 
Sharovipteryx would seemingly turn this cladogram on its head. 

This cladogram seems to use suprageneric taxa (Tanystropheus includes? or 
equals? Protorosauria) (Gephyrosaurus equal Lepidosauria) etc. which Dr. Unwin 
has already warned us about in 2003. Better to use museum inventory numbers.



Clarification: woven bone: this is not a strict basket weave, as in looping 
under or over, but as others have noted and described it as, more of a plywood 
effect, layers of cross grained patterns -- in the adult. In my opinion this is 
the end result in the mature bone of  solidification and multiplication of a 
simpler single, double then triple layered cross-grained pattern in neonates. 
The basket weave effect would be (hypothetically) achieved in juveniles via 
cellular adhesion of one layer with another as layers are added. 



 

Chris Taylor reported:

Because they occassionally rear their plucked-chicken-like heads on the
list:

Senter, P. 2004. Phylogeny of Drepanosauridae (Reptilia: Diapsida). Journal
of Systematic Palaeontology 2 (3): 257-268.
Available for Fwee!
http://journals.cambridge.org/bin/bladerunner?30REQEVENT=&REQAUTH=0&117000RE
QSUB=&REQINT1=252638

"Phylogenetic analysis reveals that the Triassic diapsid family
Drepanosauridae is closely related to Coelurosauravus and Longisquama. These
three taxa are part of a clade for which the name Avicephala (defined as all
taxa more closely related to Coelurosauravus and Megalancosaurus than to
Neodiapsida) is coined. Avicephala is a sister taxon to Neodiapsida. The
name Simiosauria is erected for the clade composed of all taxa more closely
related to Drepanosauridae than to Coelurosauravus or Sauria. Simiosauria is
composed of MCSNB 4751 + (Hypuronector + Drepanosauridae). Drepanosauridae
is composed of Drepanosaurus + (Dolabrosaurus + Megalancosaurus).
Arboreality is probably plesiomorphic for Avicephala and no convincing
evidence exists that any simiosaurian was aquatic."

Amongst the conclusions: Drepanosaurids are stem group diapsids, not
archosauromorphs, and not related to prolacertiformes. Archaeopteryx,
Ornitholestes and Sinosauropteryx were included in the analysis to test the
Feducci-oid theory that birds are derived from Avicephala - they're not.
Pterosaurs were not included, and not even mentioned in the article.
Tree:

0--Palaeothyris
 `--+--Petrolacosaurus
    `--+--Avicephala
       |        |--+--Longisquama
       |        |  `--Coelurosauravus
       |        `--Drepanosauridae
       `--+--Youngina
          `--+--Gephyrosaurus (for Lepidosauria)
             `--+--Mesosuchus
                `--+--Prolacertiformes (incl. Tanystropheidae)
                   `--Archosauriformes

    Forgive my ignorance, but what sort of a beastie is _Mesosuchus_?