Re: Refutations and the Middle J (was Re: Another Alxasaurus query & others)

["John V Jackson" <jjackson@interalpha.co.uk>]

--Original Message-- From: Thomas R. Holtz, Jr. <th81@umail.umd.edu>
To: jjackson@interalpha.co.uk Cc: dinosaur@usc.edu Date: Tuesday, February
09, 1999 11:27 PM



>At 07:29 PM 2/9/99 -0000, John Jackson wrote:
>
>>>Now, to be fair, none of these studies currently *published* test what is
>>>needed to refute Olshevsky's assertion: namely an analysis where
>>>prosauropods and/or ornithischians are also included among the ingroups,
so
>>>that (in terms of the search mechanics) recovery of a
>>>prosauropod-therizinosauorid clade is at least possible.
>>
>>The word "refute" is commonly taken in scientific circles to imply
absolute
>>certainty, or at least as certain as we can get about anything (as in "The
>>sun will rise tomorrow").
>
>Maybe in your circles, but not in the scientific circles that I know.
Point
>A-T, as Popperians, scientists recognize that we cannot determine anything
>to absolute certainty.  However, this is not the epistemology & ontology
>list, so we won't go into that any further: for those interested, consult
>just about any book on the philosophy of science.

Thanks.  I have been.

>
>Point C-G, "refute" is typically used in the scientific circles in which I
>am familiar (functional morphology, sed/strat, systematics, evolutionary
>biology, etc.) as the antonym of "support" (and thus a synonym of
"reject").
>New evidence comes around and may either support a previous hypothesis,
>refute/reject it, or be equivocal.
>
>Just hoping to clarify the terminology.

It's worth clarifying because there will have been a lot of people reading
the original message with the original meaning of the word.


>
>And, with regards to therizinosauroid relationships, Greg Paul has in more
>recent works (e.g., The Complete Illustrated Guide to Dinosaur Skeletons)
>included this (admittedly bizarre) taxon within the protoavian theropods.

My point referred to the status of the evidence, not my opinion on Theriz's.


>
>In a separate post, John Jackson writes:
>>>Sorry, realised just after sending the email - the supposed "gap" is
from:
>>>
>>> the last _Coelophysis_ and _Dilophosaurus_ about 197 mya,
>>>         mid Pliensbachian, early Jurassic,
>>>to
>>>  _Gasosaurus_, closely followed by _Proceratosaurus_ and the first
>>>   _Megalosaurus_ about 173 mya, Bathonian, mid Jurassic.
>>
>>So yes, I was aware of it.  It's worth remembering the gap ends about
23mys
>>before Archaeopteryx, and between the end of the gap and the end of the J
>>there are quite a few smallish types known.
>
>Actually, there AREN'T a lot of smallish types known.  I wish there were
>(BOY, do I wish there were!!).
>
>Between the Bathonian and the Tithonian there are very few small theropods
>known.  Other than the Morrison forms (_Ornitholestes_, _Coelurus_, the
>unnamed Dry Mesa maniraptoran, the unnamed cervicals of Makovicky 1997)

As I said up to "the end of the J", we can add Compsognathus, and that makes
about five per 23 mys.  Not as many as we would like, but if the K could
manage that average over the whole of its 80mys it would have over 17.

>there are, well... nada.  Zilch.  Zippo.

...other than them, that is.


>At least in terms of non-teeth:


>
>><but how can you know that they
>>>didn't live at that time when you have virtually NO terestrial deposition
>>>during that time anywhere on Earth?
>>
>>No terrestrial deposition in a significant period (say 23mys) prior to
_Ax_?
>>Are you sure this is what you want to say?
>
>He probably wanted to say something to that effect.
>
>What would probably be more accurate is that we have virtually no
>terrestrial deposition *preserved* from the Middle Jurassic and early Late
>Jurassic.
>
>Really.

I'm sorry but I include Tendaguru & the Morrison.



>
>This is why Peter really, really, really, really, really, really, really
>emphasized the fact that you have to crack a book on historical geology
once
>or twice to understand paleontology.  PDW is good, and I keep a copy in my
>office, but it is by no means the be all and end all of dinosaur
>paleontology (nor intended as such).  One really *must* learn something
>about geology (in general terms, and in the specifics of geologic history)
>to be able to have an informed discussion on this subject.

Excuse me but my parents taught geology, and I was going on geology field
trips before you were born.  I remember particularly well the blockheaded
resistance the continental drift theory met with.  I also remember the first
time I wrote to you I had to mention your patronising habit of suggesting
that
ignorance was the cause of my disagreeing with you.  You're still wrong on
that.