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Re: Follow-up: the truth about killer dinosaurs
Michael Mortimer wrote:
Dilong doesn't not show it though. Remember, the soft tissue over the body
often decayed in Yixian animals. That's why we get halos of integument for
the most part in coelurosaurs. In Dilong, we have tail feathers dorsal and
ventral to the vertebrae and chevrons, with absolutely nothing preserved
where any skin or scales would be.
IMHO this is probably due to taphonomy. For some reason, the feather
impressions were preserved in this sedimentary environment, but the
scales/scutellae were not. The _Archaeopteryx_ specimens preserve evidence
of feathers, but no scales, even though parts of the body (e.g., face, feet,
maybe the hands) were undoubtedly scaly in life. Similarly, the internal
organs decayed before they could leave any impression. Compare this to
_Scipionyx_, where we have guts but no integument. Those microbes are
T. Michael Keesey wrote:
It is true that the only known feathers in non-maniraptorans appear to
be for insulation. But a _T. rex_ would have benefitted from
insulation throughout much of its early life, and it would be simpler
to reduce the feathers (or even just not grow them any further--let
them stay the same size and, as the animal's surface area increases,
they spread apart) as it grew bigger than it would be to molt them and
replace them with scales. Maybe that's what they did, but it seems
like a more complicated scenario than is required to fit the known
I would argue that the first feathered theropods had both scales and
proto-feathers over the body. In the course of evolution, the former
gradually disappeared from most of the body surface, but remained on the
feet and part of the head.
Yes, but _Carnotaurus_ lies well outside the clade of feathered theropods
(all of which are coelurosaurs). I think there is also a juvenile
_Allosaurus_ specimen showing scales--what this suggests is that feathery
integument evolved somewhere within non-tyrannoraptoran
Yes, at the moment the phylogenetic bracket for feathers is hovering
somewhere around the base of the Coelurosauria, with compsognathids and
tyrannosauroids the most basal *known* theropods to display this kind of
integument. This does not mean that carnosaurs, ceratosaurs, herrerasaurs
were not feathered; but applying the principal of phylogenetic bracketing we
cannot infer the existence of feathery integument in these non-coelurosaur
groups with any confidence.
(Of course, there are also those weird quills in that _Psittacosaurus_ to
Yes, this could change things. There's a fellow named George Olshevsky who
has a lot to say about this...
David Marjanovic wrote:
At least one _Microraptor_ specimen
shows a mane-like crest -
Does it? Or is that just yet another artifact of 2D preservation of a
Here's what Xu et al. (2003) say about the feathery crest of _Microraptor
"The body is covered by plumulaceous feathers that are about 25−30 mm
long. The feathers attached to the skull roof are up to 40 mm long in IVPP
V13352 (Fig. 2a), and in TNP00996 they are proportionately even longer (Fig.
2b). Some feathers on the head display well-organized pennaceous vanes
(Fig. 2c). These feathers are most probably functionally related to
display, as in some modern birds such as _Pithecophaga jefferyi_. Large
pennaceous feathers are attached to the distal tail, forelimb and hindlimb
(Figs 1a, c and 2d−g)."
My hair points away in all directions when I dive and don't move too fast.
Well, if your hair makes you look like a dead _Microraptor_, I would consult