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Re: Oviraptorosaur tail forms and functions

Oh and one more thing.  Could someone *please* come up with a new name
for the preoccupied genus "_Ingenia_".  And by "someone" I mean a
vertebrate paleontologist - not an entomologist or helminthologist who
wants to give it a dumb-ass name meaning "big dead lizard" or
something.  ;-)

On Wed, Jan 9, 2013 at 1:14 PM, Tim Williams <tijawi@gmail.com> wrote:
>> W. Scott Persons, IV, Philip J. Currie, and Mark A. Norell
>> Oviraptorosaur tail forms and functions.
>> Acta Palaeontologica Polonica (in press)
>> doi: http://dx.doi.org/10.4202/app.2012.0093
>> http://app.pan.pl/article/item/app20120093.html
> It's certainly interesting how muscular and flexible the tails of
> these oviraptorosaurs were.  It's tempting to reconstruct
> oviraptorosaurs as having an elaborate terminal tail "fan" (e.g.
> www.wired.com/wiredscience/2013/01/dinosaur-courtship-feathers), with
> the impressive caudal musculature used to wave the fan around during
> courtship or threat postures.  However, I wonder if the tail was a
> little 'over-engineered' for display purposes alone.  Perhaps the tail
> was used as a weapon instead, and swung side-to-side to clobber any
> predators that came too close.  I'm not convinced that the presence of
> a pygostyle necessarily indicates the attachment of large pennaceous
> feathers at the end of the tail.  Although large terminal tail
> feathers are present in caudipterygids, these were small animals with
> extremely short (and presumably weak) tails by oviraptorosaurian
> standards - as Persons et al. note.
> The array of feathers inferred to have attached to the pygostyle of
> oviraptorosaurs is referred to as a "fan".  I'm not sure this is the
> best term.  Firstly, it recalls the tail fan of modern birds, which is
> a highly specialized aerodynamic structure controlled by rectricial
> bulbs, used to modulate lift forces during flight.  Secondly, it is
> not known if the tail feathers attached to the oviraptorosaurian
> pygostyle actually formed a radial array; perhaps it was just a
> terminal "frond", as inferred for _Caudipteryx_ (Gatesy, 2001).  There
> are many basal avialans that have a pygostyle, but no pennaceous
> rectrices, and certainly not a true tail fan.
> That's assuming that the larger pygostyle-bearing oviraptorosaurs
> (like _Nomingia_, _Citipati_ and _Conchoraptor_) had large terminal
> tail feathers at all.  Like I said, it wouldn't surprise me if the
> hefty muscularized tail was used as a weapon (intraspecific combat?;
> defense against approaching predators?), and so would likely lack a
> tail-feather fan.
> On another topic, from the paper:
> "A large M. caudofemoralis is a characteristic of basal
> theropods (Gatesy 1990a; Persons and Currie 2011a). In avialans and
> deinonychosaurs, the M.
> caudofemoralis is greatly reduced in size or altogether absent, and
> the stroke mechanics of the
> hind limbs emphasize knee-flexion, rather than femoral retraction
> (Gatesy 1990a, 1990b; Persons
> and Currie in press)."
> I may be reading too much into this, but is it saying here that even
> deinonychosaurs and basal birds had knee-based stride generation, not
> just more derived birds (which was my impression)?  It's hard for me
> to imagine _Velociraptor_ walking around like a ground bird, with the
> femora tucked under the body and stride generation occurring at the
> knee....
> Cheers
> Tim