[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
RE: a curious contradiction regarding RT
On Jan. 17, 1997, Terry Jones wrote:
>Leahy's communication re turbinates in nodosaurs is both misleading and
I strongly disagree with Terry's characterization of my posting
as "misleading" and "irresponsible". Terry made a statement on this list
which contradicted information given to me by another one of his co-authors
of the _Science_ paper. I noted what the discrepancy was, and asked list
members if anyone could shed light on this discrepancy. It's never
"misleading" or "irresponsible" to attempt to find out where the truth
>In order to be most useful for our study, dino skulls had to be preserved
>three dimensionally with minimum bilateral distortion. Leitch's nodosaur
>skull does not meet these criteria.
This answers the nodosaur question I asked in my original comment.
Unfortunately, Terry still does not address the discrepancy regarding the
>Leahy also misleads readers by stating that the nodosaur skull shows
>evidence of "turbinates," thus leaving the impression that it showed
>evidence of RTs. It does not.
Terry's making accusations that have no basis in reality. My use
of the term "turbinate" was an attempt _not_ to mislead readers. Because
the turbinate in the nodosaur has not (to the best of my knowledge) been
published, I did not know whether the turbinate was respiratory or
olfactory. To say the turbinate was either, in the absence of additional
information, _would_ have been "misleading" and "irresponsible".
>We resent Leahy's implication that somehow we intentionally left
>specimens out of our study that might have been at variance with our
Again, Terry's misinterpreting my comment. Nowhere did I imply this.
However, their conclusions would be strengthened if they _did_ use taxa
which _might_ be at variance with their conclusions (such as
Procellariiformes, kiwis, hornbills, monotremes, chameleons and whales)
and they still found the same results.
>leahy's comments re narrow nasal structure in fulmars only serves to
>further mislead readers.
I don't see how mentioning anatomical facts misleads anyone.
My comment re fulmars was...
"Fulmars are a member of the avian order Procellariiformes, a
group characterized by very narrow, tubelike nasal cavities. Despite this,
fulmars, like other Procellariiformes, have RT".
There's nothing "misleading" about this statement. It's all true.
Go read Bang (1966).
>The tubular portion of the procellariiform (e.g., fulmar and other tube-
>nosed birds) nasal passage (to which Leahy refers) corresponds to the
>nostril and vestibular region--an area which doesn't house the main
>RTs and, therefore, has no particular reason to have undergone expansion.
Not entirely true. In some birds, such as gulls, cassowaries and
rheas, the main RT does extend into the vestibular region (see Bang, 1971
Bang, 1961 and Technau, 1936). In addition, the vestibular region _does_
house a separate set of RT, a point conceded in the _Science_ paper...
"Birds generally possess an additional, anterior set of respiratory
turbinates located within the rostral vestibular region" (p. 1206).
Elsewhere in the Science paper...
"Expansion of the nasal cavity is is necessary to accommodate the presence
of respiratory turbinates, as well as to facilitate increased lung
ventilation rates in endotherms".
If expansion of the nasal cavity is needed to accommodate RTs, and
to facilitate increased ventilation, such expansion should be the case
for _all_ sections of the nasal cavity that house RTs. After all, air
must flow through the vestibular region in order to reach the main nasal
cavity! The tubelike vestibules of Procellariiformes and kiwis are
inconsistent with the idea that large nasal cavity cross sectional areas
are needed to support endotherm respiratory needs. It's also illogical
and inconsistent to argue the tubelike nasal cavities of some dinosaurs
were to small to house RT, when the tubelike nasal cavities of kiwis and
Procellariiformes _do_ house RT. In addition, RTs can markedly increase
airflow resistance (Moulton, 1967), so it seems self-defeating to reduce
airflow resistance by enlarging the nasal cavity. only to increase
airflow resistance again by plugging up the nasal cavity with RT.
Bang, B. G. (1966) The olfactory apparatus of tubenosed birds
(Procellariiformes). Acta Anatomica, 65, 391-415.
Bang, B. G. (1961). The surface pattern of the nasal mucosa and
its relation to mucous flow-a study of chicken and herring gull mucosae.
Journal of Morphology, 109, 57-72.
Bang, B. G. (1971). Functional anatomy of the olfactory system in
23 orders of birds. Acta Anatomica (supplementum 58), 79, 1-74.
Moulton, D. G. (1967). Olfaction in mammals. American Zoologist,
Technau, G. (1936). Die nasendruse der vogel. Journal dur
Dept. of PEHR
Western Washington University
Bellingham, WA 98225