Osteichthyes ( was: Re: The Lost Dinosaurs Of Egypt ... and insects)

["Steve Brusatte" <dinoland@lycos.com>]

On Wed, 5 Jun 2002 17:26:22   
 David Marjanovic wrote:
>...and some
>new trees get Placodermi and Osteichthyes as sister groups...

Refs...please. :-)  I'm really lacking knowledge when it comes to "fish," but I 
know of only one study that has placed placoderms and osteichthyans as possible 
sister groups (Janiver, P.E. Early Vertebrates. Oxford University Press, 1996). 
 I'm sure there are more.  

Zhu et al., in a Nature article describing the weird Devonian fish 
_Psarolepis_, actually found Osteichthyes united by no synapomorphy, but 
supported only by homoplasies.  They offered a real tentative cladogram showing 
placoderms as the sister taxon to chondrichthyans+ acanthodians and 
osteichthyans.  But, this analysis was preliminary, especially considering that 
_Psarolepis_ is basically a mix of traditional placoderm, sarcopterygian, and 
actinopterygian characters.  So, it's difficult to deduce the polarity of 
certain characters, which might make much of the aforementioned analysis 
incorrect.  

However, that paper was published three years ago.  A commentary article 
mentions some newer discoveries awaiting publication.  Have any of these been 
described yet?

Steve  

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