Re: Bakker's Brontosaurus and Late Cretaceous populations

[Tim Williams <twilliams_alpha@hotmail.com>]

David Marjanovic wrote:

> > Against the flow, heroic efforts have been made to reinstate 
> > _Brontosaurus_;
> > and I don't know what to make of _Eobrontosaurus_.
>
> Hasn't someone just let it disappear in *Camarasaurus*...?

This was in the Sauropoda chapter of the new Dinosauria volume.  (I'm just 
passing the info on, so don't take this as an endorsement on my part that 
_Eobrontosaurus_ has 'disappeared' into _Camarasaurus_.)

> Do you mean *"Dilophosaurus" sinensis* has been renamed??? ~:-|

Not that I know of.  What I was driving at is that it has been recognized 
that _D. sinensis_ does not belong in _Dilophosaurus_, just as _C. 
maortuensis_ does not belong in _Chilantaisaurus_ (and I do know a new genus 
name has been proposed for _maortuensis_).

> *Efraasia* is not even a prosauropod, so that's not a case of 
> splitting/lumping.

It was once thought that _Efraasia diagnostica_ (=_Palaeosaurus 
diagnosticus_) was based on a juvenile specimen of _Sellosaurus_ 
(=_Plateosaurus_), so it was sunk as a junior synonym of _Plateosaurus_ or 
_Sellosaurus_ (e.g., Galton, 1990).  Recent studies have reinstated the 
genus _Efraasia_ as valid.  So on this point, it is a case of 
splitting/lumping.

> Would be really great to have a phylogeny of *Psittacosaurus*. Even the 
> attempt to synonymise > the species into four is so old (1993?) that 2 or 3 
> species have been described since.

When it comes to _Psittacosaurus_, my genus-meter goes off the dial.  :-)  
Admittedly, there is no evidence that the genus is polyphyletic or even 
paraphyletic.

Cheers

Tim