OCCAM'S RAZOR & THERIZINOSAURS

[darren.naish@port.ac.uk]

On that oft-discussed subject of where therizinosaurs fall out within 
Theropoda, Pete Buchholz, he of the consistently misspelt name, 
wrote...

> Indeed, all saurischians have pneumatic vertebrae with pleurocoels.  
> The point I believe Jim was making is that Brooks was showing that 
> the pleurocoels of therizinosaur cervicals had vertebrae that were 
> pneumaticised in a similar manner as those of Ornithomimids etc, not 
> the simple invagination seen in Anchisaurus cervicals.

Clearly at the moment the extensively pneumaticised cervical 
verts (and don't forget, with specific regard to this issue, that 
Pete Makovicky - whose thesis was on coelurosaurian verts - supports 
a close association of therizinosaurs and oviraptorosaurs), 
coelurosaurian briancase wiring, maniraptoriform hands and wrists and 
inflated braincase bones make it most parsimonious to regard 
therizinosaurs as theropods: this is my view via simple application 
of Occam's razor. Plus the fact that every theropod worker*, without 
exception so far as I know, finds Therizinosauroidea nested somewhere 
within Theropoda. 

However, I honestly would not have expected the presence of a 
therizinosaur in the Lower Jurassic. Does everyone advocating a 
bullatosaurian or oviraptorosaurian affinity of therizinosaurs really 
appreciate what this means? 

(Or, is Chatterjee right??)

> Second.  Coeluria should be regarded as a nomen oblitum because as 
> far as I know, only Marsh and George have ever used the name

GSP used it too, in PDOTW. And I don't *think* 'forgotten name' rules 
apply to higher taxa. Is this correct? Having said that, I do not 
disagree with Pete as to the idiosyncratic use of Coeluria.  

*By 'worker' I am referring to all those palaeontologists who have 
published technical descriptive studies of members of Theropoda.

"Ok.. who's next?"

DARREN NAISH
darren.naish@port.ac.uk