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Re: DINO NOTES



> LN Jeff (Martz) says: No theropod ever had sauropod genes.
> Uh... Didn't both Sauros and Theros come from the same place (Sauro-Thero,
> or Saurischiasaurus, the so-far unseen ancestor of all Lizzard Hippers?)
> and hence, didn't both theros and sauros have the same basic generic
> source? After all, the long-necks of Sauros and S-necks of Theors come
> from the same source. 

     Yes, but this source was not a true theropod or a true sauropod.  
My interpretation of the original message was that it was being inferred 
that segnosaurs were:

1.  Theropods that started expressing charaters evolved by true 
sauropods AFTER theropods and sauropods had already diverged.

or...

2.  Sauropods that started expressing characters evolved by true 
theropods AFTER theropods and sauropods had already diverged.

     The only way that either of these scenerios could occur is if 
interbreeding with viable offspring occured between sauropods and 
theropods, something that is unlikely to say the least.

In which case, if SauroThero had genes 1 and 2 and
> the Sauros turned off #1 and the Theros turned off #2 and the Segnos show
> both #1 and #2, then could not the mysterious Segnos have (as I noted in
> the three options I listed) have either:
> 1. Descended from a Thero who suddenly remembered gene #2
> 2. Descended from a Sauro who suddenly remembered gene #1
> 3. Descended via unknown link from SauroThero who had both #1 and #2?
> Hardly looks impossible to have been #1, although I personally favor #3.

     If this is what was meant, then yeah, it would be possible.  It 
would be very unusual for a gene that remained inactive for millions of 
years to become activated.  Considering the animal had evolved 
considerably in that time, I would think that these ancestral charaters 
meshing smoothly with the animal's derived anatomy would be just as odd. 
Personally, I think covergent evolution is a more likely agent that 
reactivated genes.

LN Jeff