RE: Ligabuesaurus leanzai

[Tim Williams <twilliams_alpha@hotmail.com>]

Brad McFeeters wrote:

> Bonaparte, J.F., González Riga, B.J. & S. Apesteguía, 2006.  Ligabuesaurus 
> leanzai gen. et sp. nov. (Dinosauria, Sauropoda), a new titanosaur from the 
> Lohan Cura Formation (Aptian, Lower Cretaceous) of Neuquén, Patagonia, 
> Argentina.  Cretaceous Research, in press.

AFAIK, this is the THIRD dinosaur to be named after Dr Giancarlo Ligabue, 
together with two other South American taxa, _Ligabueino andesi_ (theropod) 
and _Agustina ligabuei_ (sauropod).  Trivia question: Is there anybody who's 
had more dinosaurs named after him/her?  (I know Ned Colbert has three.)

The humerus/femur ratio of _Ligabuesaurus_ is 0.9 (1.49m/1.66m), which is a 
little bigger than _Chubutisaurus_ (0.86).  It's not clear if such long 
forelimbs evolved independently of true brachiosaurids, or is plesiomorphic 
for titanosauriforms.  If the latter is true, this could undermine the 
monophyly of Brachiosauridae (my opinion, not the authors') - especially 
since there are similarities in the cervicals between _Ligabuesaurus_, 
_Brachiosaurus_ ("Giraffatitan"), and _Sauroposeidon_.

_Ligabuesaurus_'s closest relative appears to be _Phuwiangosaurus_.  Given 
that _Ligabuesaurus_ is recovered as above _Brachiosaurus_ but below 
_Andesaurus_, it would be a titanosaur under Wilson and Sereno's (1998) 
stem-based definition ("titanosauriforms closer to _Saltasaurus_ than to 
_Brachiosaurus_ and _Euhelopus_"), which was essentially followed by Sereno 
(2005).  However, under Salgado et al's (1997) node-based definition ("all 
descendents of the most recent common ancestor of _Andesaurus_ and 
Titanosauridae"), _Ligabuesaurus_  would not be a titanosaur.  Though given 
that Titanosauridae is not accepted as a valid taxon, that definition is 
probably passe.

No body armor is preserved.

Cheers

Tim