RE: Ceratonykus braincase described

[Mickey Mortimer <mickey_mortimer111@msn.com>]

Tim Williams wrote-

> On another alvarezsaur-related issue, Alifanov and Saveliev poo-poo
> the proposed alvarezsaur affinities of _Haplocheirus_. I initially
> didn't understand their reasoning: "because the manus of this species
> displays typical theropod features." But it's apparent later on in
> the paper that the authors have some pretty heterodox views on the
> evolutionary history of alvarezsaurs. 

Yup, this dates to the original Ceratonykus paper.  As I wrote then... 

Alifanov and Barsbold question the placement of alvarezsaurids within 
Theropoda, 
  but their reasoning is not cladistic, based largely on autapomorphies (dorsal 
  jugal process absent; dorsal quadratojugal process absent; postorbital 
contacts 
  quadrate; ventral flexure of endocranium absent; posteroventral dentary 
process 
  absent; fused sternal plates; highly flattened metacarpal I; pubic symphysis 
  absent), characters absent in basal members (fused metacarpals; proximally 
placed 
  pubic tubercle; metatarsal III does not reach tarsus), characters present in 
  related theropods (enlarged prefrontal; dentary teeth in common groove; 
procoelous 
  caudal centra; obturator fenestra absent in pubis), and characters unknown in 
  alvarezsaurids (gastralia absent; pentadactyl manus). Other theropods are 
known 
  to have lost dorsal jugal and quadratojugal processes, to have fused their 
sterna, 
  and lost their pubic symphyses as well, of course. The remaining 
autapomorphies 
  are unique among archosaurs as far as I know. The authors state "it is 
  interesting that many of the characters listed are recorded in 
ornithischians", 
  but while Lesothosaurus has enlarged prefrontals (primitive for archosaurs), 
  a flattened metacarpal I and a proximally placed pubic tuber, the other 
characters 
  listed and present in alvarezsaurids are absent. The synapomorphies shared by 
  Theropoda and its subgroups are far more numerous, and any suggestion for 
placing 
  alvarezsaurids outside that clade can be ignored. 

It's one of those many times that make you wonder where the reviewers were (or 
how much input Barsbold had).  Russia seems to be stuck in the 70's where 
phylogenetics is concerned, resulting in heterodox hypotheses, since there's no 
constraint like parsimony to hold them in check.  A similar example is 
Ivakhnenko's (2009) "Eotherapsid hypothesis for the origin of Monotremata."  It 
has monotremes evolving from anomodonts and supports groups no cladist believes 
in, like "Eotherapsida" containing sphenacodonts and some therapsids, but not 
cynodonts and mammals.  And there's Kurochkin's "enantiornithines are theropods 
but ornithuromorphs aren't" ideas.  Do they just lack access to new articles?  
Are the professors all 'old school' and pass on outdated thinking to their 
students?

Ivakhnenko, 2009. Eotherapsid hypothesis for the origin of Monotremata. 
Paleontological Journal. 43(3), 237–250.

Alifanov and Barsbold, 2009. Ceratonykus oculatus gen. et sp. nov., a 
  new dinosaur (?Theropoda, Alvarezsauria) from the Late Cretaceous of 
Mongolia. 
  Paleontological Journal (English edition). 43(1), 94-106.

Mickey Mortimer