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Re: Most dinosaurs were scaly

----- Original Message -----

> From: Matt Martyniuk <martyniuk@gmail.com>
> To: Jura <pristichampsus@yahoo.com>
> Cc: "dinosaur@usc.edu" <dinosaur@usc.edu>
> Sent: Tuesday, 31 December 2013 7:31 AM
> Subject: Re: Most dinosaurs were scaly
>& quot;Again I cite Yutyrannus as an example of why, but one can also look at 
> general patterns of integument we see in extant taxa too. It's not just that 
> Yutyrannus shows no loss of filaments with its large size, it's that it 
> shows no scales on its hide either.”
> Neither do a vast majority of ornithodiran specimens from lagerstatten/fine 
> grained sediments, including euornithean bird feet, hadrosaur hides, etc. 
> Were 
> these all secondarily bare skinned? Obviously there is a sedimentological 
> bias 
> against scale preservation in fine-grained shale, at least in larger-boies 
> animals (scale preservation in lizards and choristoderes in the same 
> sediments 
> seems marginally more common).


All of those examples didn't preserved any soft tissue in the areas in 
question. It's not that scales weren't preserved, it was that nothing but bone 
was preserved. Pelecanimimus is the only animal I can think of that preserved a 
hide without scales or filaments.


> The hypothesis that Yutyrannus independently evolved a more extensive feather 
> covering and that other tyrannosaurs retained scales elsewhere on the torso 
> is 
> just as parsimonious as the hypothesis that… what’s the alternative you’re 
> suggesting? That Yutyrannus is not a tyrannosaur and tyrannosaurs are scaly 
> non-coelurosaurs? If you contend that eve/devo says it’s all or nothing 
> feathers 
> or scales and the ancestral feathered animal was feathered head to toe, than 
> Yutyrannus must be closer to birds than to Gorgosaurus, right? I’ve heard 
> people 
> suggest that Yutyrannus is actually related to carcharodontosaurs but never 
> that 
> it’s more derived than t
urs among coelurosauria.


I never said anything about them being non-coelurosaurs (though I suppose that 
could be possible), only that some animals currently placed in Tyrannosauroidea 
may wind up being closer to maniraptors than originally thought. Tyrannosauria 
has already started falling down the tree closer to the base of Coelurosauria, 
and non-tyrannosaurid tyrannosauroids (ick, so clunky) have such weak tree 
support as it is that I wouldn't be surprised if future analyses rearranged the 
membership of that clade. We already saw that happen twice with Dilong. I 
haven't seen Yutyrannus pop up in many phylogenies since its discovery so 
things are still pretty early there.