Re: Postorbital processes on jugals

["David Marjanovic" <david.marjanovic@gmx.at>]

>      Assuming that the said processes have only been lost in mononykines
and
> the "non-confuciusornithid ornithothoraceans"

Pygostylians. Pygostylia = {*Confuciusornis* + *Passer*}; Ornithothoraces =
{*Sinornis* + *Passer*}.

> (mercy, how about that for a
> phrase to torture the speaker's mouth and the listener's brain)

Let's give it a name :-)

> ---- why
> would a single loss (plus a reversal) be preferable to two independent
> losses?
> [...]
> Both scenarios require two steps,

That's it. None is a priori preferable. If there is a bird in the above
clade that has the process then 2 losses are definitely more parsimonious.
If there is none, but if there is a non-pygostylian metornithine that also
lacks the process, then a reversal is definitely more parsimonious.
Candidates for the latter position exist, but none has a skull. Therefore
I'm asking about the former position.

>      I guess it depends on what the function of the process is, but off
> hand, it seems like two independent losses might be more likely than one
> loss and a reversal.

Why?