Re: when is a Lazarus Taxon not a Lazarus Taxon?

[Tim Williams <twilliams_alpha@hotmail.com>]

Mike Taylor wrote:

> Ladies and gentlemen, I give you: _Dravidosaurus_.  This Indian form from 
> the Coniacian seems to be a stegosaur (Yadagiri and Ayyasami 1979, Galton 
> and Upchurch 2004), contra Chatterjee and Ruda 1996.  If that's correct, 
> then it has a whopping forty-million-year ghost lineage since the 
> next-youngest known stegosaur, _Regnosaurus_ from the Wealden 
> (Hauterivian-Barremian) of England (Sereno and Upchurch 1995).

_Wuerhosaurus_ may be younger than _Regnosaurus_, or at least coeval.  But 
you're right; if _Dravidosaurus_ is a stegosaur, that's a very long ghost 
lineage indeed.  However, although it's listed as a stegosaur by Galton and 
Upchurch (2004), I think this assignment is still questionable.

I was wondering if _Sonorasaurus_ might qualify as a Lazarus taxon, given 
(a) it is said to be of Cenomanian age (Carpenter and Tidwell, 2004); and 
(b) it is strikingly similar (identical?) to Late Jurassic _Brachiosaurus_ 
(Curtice, 2000) .

Cheers

Tim

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