[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Query on so-called "correlated" characters, reply



Admitting that you are trying to test the position of pterosaurs as
not being archosauriforms, it is logical not to consider the
antorbital fenestra and fossa as necessarily correlated with paranasal
sinuses as in Archosauria. In such a case, you hav more arguments for
considering fenestra and fossa as not necessarily correlated, and not
necessarily correlated to the archosaurian soft tiessues. This does
not imply that if you recover pterosaurs as archosaurs, you should
explain these soft tissues as holding the structures they hold in
other archosaurs.

I am not sure a fenestra has to be conformed by union of foramina, I
do not remember examples, but there seem to be examples of fenestrae
that later form foramina (epioptic fenestra in neurocranium seems to
close to encircle ethmoid artery in sauropods and perhaps some birds),
and of enlarged foramina, as the mammalian obturator fenestra. And, as
David (M) said, there are fenestrae which hardly have something to do
with nerves and blood vessels.

2009/5/24 David Peters <davidpeters@att.net>:
>
> regarding foramina and fenestra, in fossils you have no idea what that tiny 
> hole is used for in taxa with no living relatives. True, most were typical of 
> living taxa. A few might be the genesis of larger fenestra.
>
> David Peters
> 1247 Highland Terrace
> St. Louis, MO  63117-1712
> 314-781-1795 phone and fax
> 314-323-7776 cell
>
> davidpeters@att.net
>
>
> --- On Sat, 5/23/09, Augusto Haro <augustoharo@gmail.com> wrote:
>
>> From: Augusto Haro <augustoharo@gmail.com>
>> Subject: Re: Query on so-called "correlated" characters, reply
>> To: david.marjanovic@gmx.at
>> Cc: "David Peters" <davidpeters@att.net>, "DML" <dinosaur@usc.edu>
>> Date: Saturday, May 23, 2009, 10:08 AM
>> sorry the foramens (sic) and other
>> "sics" around the text
>>
>> 2009/5/23 Augusto Haro <augustoharo@gmail.com>:
>> > 2009/5/22 David Marjanovic <david.marjanovic@gmx.at>:
>> >> ----- Original Message -----
>> >> From: "David Peters" <davidpeters@att.net>
>> >> Sent: Saturday, May 23, 2009 12:08 AM
>> >>
>> >>>>> 2. Quadratojugal process of jugal
>> present or absent.
>> >>>>> Quadratojugal present or absent.
>> >>>>
>> >>>> The first must be scored as unknown
>> (which, for PAUP*, is the same  as
>> >>>> "inapplicable") in all taxa that lack a
>> quadratojugal.
>> >>
>> >
>> > This seems correct. I have heard of the argument of
>> making the
>> > character additive, with states quadratojugal absent
>> (0),
>> > quadratojugal present, without process (1),
>> quadratojugal present,
>> > with process, (2), as if you were progressively adding
>> things. I think
>> > this is likely not certain in this case because the
>> presence of the
>> > process is likely a by-product of the formation of the
>> infratemporal
>> > fenestra (by delay in ossification, I think to
>> remember). Being more
>> > general, if there is any other process in which we
>> observe variation,
>> > which cannot be hierarchically correlated with the
>> process already
>> > assessed, we should codify with the same logic both
>> processes, and
>> > would not consider both additive in the same sense
>> cited above because
>> > we would repeat the change from presence to absence.
>> So, I think the
>> > best option is doing what David (Marjanovic)
>> indicated.
>> >
>> >>> And there's the opposite case:
>> >>> Antorbital fenestra with or without a
>> maxillary fossa. 'Without a  fossa'
>> >>> appears on chroniosuchids, pterosaurs and
>> Proterosuchus, which  are not
>> >>> related. The fossa is not necessarily
>> correlated to the  presence of a
>> >>> fenestra. It either is present, or it is not.
>> >>
>> >> I'd say they're simply correlated the other way
>> around: the fossa is only
>> >> present if the fenestra is present, never
>> otherwise. One ordered multistate
>> >> character: both absent (0), fenestra present and
>> fossa absent (1), both
>> >> present (2).
>> >>
>> > Well, in this case I think that we can alternatively
>> consider both as
>> > not correlated (except hierarchically), for the
>> multistate character
>> > you proposed is operationally the same of two binary
>> characters being
>> > one presence/absence of the fossa and presence/absence
>> of the
>> > fenestra. I think the currently known distributions
>> implies the the
>> > character of David (M) is not wrong, as do the fact
>> that according to
>> > Witmer (1997, MSVP) the fossa forms by a sac
>> necessarily transversing
>> > the fenestra to reach the fossa from the nasal cavity.
>> But I think
>> > making two independent characters may better
>> accomodate, without harm,
>> > the possibility of a specimen without antorbital
>> fenestra, but which
>> > presents a fossa similar in location and depth to the
>> antorbital
>> > fossa.
>> >
>> >>>>> 4. Naris larger/smaller than
>> antorbital fenestra.    Antorbital
>> >>>>> fenestra present or absent.
>> >>>>
>> >>>> The first must be scored as unknown in all
>> taxa that lack an  antorbital
>> >>>> fenestra.
>> >>>
>> >>> >>
>> >>> Yet, if no antorbital fenestra is present,
>> isn't the naris, by  default,
>> >>> larger than the antorbital fenestra? Why not
>> score it that  way? How does an
>> >>> antorbital fenestra phylogenetically begin?
>> I've  seen foramina that might
>> >>> be the start of an antorbital fenestra. Do
>>  you ignore those?
>> >>
>> >> That needs to be demonstrated first. It needs to
>> be shown that the
>> >> antorbital fenestra starts small and then becomes
>> larger. As long as that
>> >> isn't established, it's safer to score the
>> relation character as unknown
>> >> when the fenestra isn't there.
>> >>
>> >> Why should foramina and fenestrae be homologous?
>> Foramina contain nerves
>> >> and/or blood vessels; fenestrae can, but only by
>> accident.
>> >
>> > Well, here I think we can see foramina and fenestrae
>> as part of a
>> > continuum. There are foramens which can enlarge to
>> make fenestrae
>> > within which a nerve is located, as with the obturator
>> fenestra of
>> > mammals. The suborbital fenestra of diapsids seems to
>> present a great
>> > variation in area. Their difference is in area, and
>> there are nerve
>> > foramina of different areas, and the same applies for
>> fenestrae. I
>> > think we should not deal at this point with which is
>> the origin of the
>> > fenestra; as far as we can we should only observe the
>> similarities and
>> > dissimilarities (which is not always easy).
>> >
>> > In my view, an argument for seeing the foramen closer
>> to the absent
>> > condition than the fenestra, and so including the
>> absent into a
>> > continuum, is that if we define the size as area, we
>> should say that 1
>> > cm x cm (suppose this means foramen, the character
>> should be defined
>> > better in a ratio with other feature) is closer than 0
>> cm x cm than
>> > (absent condition) than a fenestra of say, 30 cm x
>> cm.
>> >
>>
>