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Re: Heterodontosaurid with protofeathers



On Wed, Mar 18, 2009 at 5:24 PM, Tim Williams <tijawi@yahoo.com> wrote:
>
> http://dml.cmnh.org/2008Jan/msg00088.html
>
> "One possibility... is that a fuzzy body covering is primitive for 
> Ornithodira, and was retained by certain pterosaurs (like _Sordes_ etc) and 
> dinosaurs (especially small theropods), but lost (or scaled back) 
> independently in many lineages. ÂUnder this hypothesis, sauropodomorphs 
> would be secondarily 'naked'. ÂMost (and maybe all) ornithischians might be 
> naked too - either due to large body size, or to a burrowing ecology in the 
> smaller and/or more basal ornithischians. ÂThe tail 'quills' of 
> _Psittacosaurus_ could even be highly modified versions of these filamentous 
> structures. ÂThis hypothesis would mean that a fuzzy integument Âwould go 
> back to lagosuchian-grade archosaurs. ÂHighly speculative, I know, and as I 
> write this I find myself less and less convinced that it's even plausible."
>
> As I re-read this, I find this idea slightly more plausible. ÂAnd with the 
> caveat that we now have basal ornithischians (a heterodontosaur) with 
> 'dinofuzz'.

Seems we don't really know the state for most sauropodomorphs. Those
embryonic titanosaurs are scaled, but who knows about
non-titanosaurian sauropodomorphs? At the very least, early, smaller
forms like _Thecodontosaurus_, _Anchisaurus_, etc.could have been
bristly.

Related thoughts here:
http://phylonom.wildprehistory.org/viewtopic.php?f=18&t=12
-- 
T. Michael Keesey
Technical Consultant and Developer, Internet Technologies
Glendale, California