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



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.
>