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Re: tiny-armed theropods
If I understand the PhyloCode correctly, date of definition does not
take priority over date of naming. So even if Therizinosauria
(Russell, 1997) is formally defined and registered as the stem
(Therizinosaurus > Passer), even if Segnosauria (Barsbold, 1980) is
*later* formally defined and registered as (Segnosaurus > Passer),
assuming this is the same group, Segnosauria will still have priority
because the name was coined before Therizinosauria, despite the fact
that Therizinosauria was defined/registered first.
The ICPN also does away with the principle of coordination, so as far
as the ICPN is concerned, Therizinosauroidea was coined by Russell &
Dong 1994, not Maleev 1954.
On Wed, Oct 12, 2011 at 2:58 AM, Jaime Headden <email@example.com> wrote:
> *Segnosauria* is not defined as a taxon in a Family-level rank, and thus
> has no bearing with relation to *Therizinosauroidea*, the name used in
> support for *Therizinosauridae*, etc., which does have priority over
> *Segnosauridae*. *Therizinosauroidea* was used to supplant *Segnosauria* as
> the name of value for the stem, and has been kept that way based solely on
> use and the sense of "whomever defines it first shall have that name be used
> (even if the definition change) forever!"
> It's silly that, until *Therizinosauria* become used more recently,
> *Segnosauria* could still be used for the group. But this hasn't been the
> case for workers discussing therizinosaur total group, and I think the name
> will fall to disfavor unless somehow resurrected.
> Jaime A. Headden
> The Bite Stuff (site v2)
> "Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
> "Ever since man first left his cave and met a stranger with a
> different language and a new way of looking at things, the human race
> has had a dream: to kill him, so we don't have to learn his language or
> his new way of looking at things." --- Zapp Brannigan (Beast With a Billion
>> Date: Wed, 12 Oct 2011 16:28:32 +1100
>> From: firstname.lastname@example.org
>> To: email@example.com
>> Subject: Re: tiny-armed theropods
>> David Marjanovic <firstname.lastname@example.org> wrote:
>> > ...although, in ornithomimo- and segnosaurs alike, the head + neck is still
>> > longer than the forelimbs.
>> The necks of ornithomimosaurs and therizinosaurs are decidedly long.
>> And yeah... I also prefer the name 'segnosaurs' over 'therizinosaurs'.
>> ;-) But I guess the latter has priority.
>> Jason Brougham <email@example.com> wrote:
>> > I see, so you are suggesting that all theropods would benefit from
>> > reduction of their pectoral limbs if
>> > they could find a way to do without arms in feeding and brooding and
>> > whatnot, because it would
>> > make them more agile.
>> This was the essence of Carrier et al's (2001) paper on rotational
>> inertia in theropods (J Exp Biol. 2204: 3917-26). The resulting
>> agility while turning might also have driven the evolution of the
>> forelimb-folding mechanism in maniraptorans, conferred by the
>> semilunate carpal joint. (I don't buy GSP's notion that the
>> semilunate carpal evolved as a flight-related/flapping feature.)
>> > It's just that dispensing with the arms' uses must have been impossible
>> > for many theropods,
>> > possibly for a large or even an innumerable set of interacting reasons.
>> I've wondered about this. It is likely that bipedality preceded
>> predatory behavior in dinosaur evolution. The study of Martinez et
>> al. (2011) further indicates that the ancestral body plan for
>> dinosaurs included a proportionately long forelimb (~45% hindlimb
>> length) and a sharp-clawed manus capable of hyperextension. Theropods
>> show a shift to a more raptorial/grasping manus (elongate penultimate
>> phalanges of manus, etc). Nevertheless, it appears to me that once
>> dinosaurs became bipedal it was a case of: "So, what do we do now with
>> these appendages?"