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

[no subject]

This message was submitted by longrich@phoenix.princeton.edu to list
dinosaur@usc.edu. If you forward it back to the list, it will be distributed
without the paragraphs above the dashed line. You may edit the Subject: line
and the text of the message before forwarding it back.

If you edit the messages you receive into a digest, you will need to remove
these paragraphs and the dashed line before mailing the result to the list.
Finally, if you need more information from the author of this message, you
should be able to do so by simply replying to this note.

----------------------- Message requiring your approval ----------------------
Sender: longrich@phoenix.princeton.edu

On Thu, 29 Aug 1996, Jerry D. Harris wrote:
>         BTW, this message also serves as a test message; has this list been
> dead of late, or is it just me???

        Sure seems that way. I actually have a couple questions I've been 
wondering about... one of them is that I recently saw a structure in 
nature that is the only thing I can think of that paralells the evolution 
of feathers. It serves an aerodynamic, rather than insulatory, purpose, 
and someone has told me that these little tufts of down are from the 
thistle plant. The actual structure of each "plume" is a central shaft 
with secondary hairs branching off, it vaguely resembles the ratite 
feathers. The thistle down implies to me that even a 
relatively simple, ratite-like feather might have some serious aerodynamic 
advantages over simple hairs. On the subject of feathers, I'm surprised 
no one ventured to speculate where the one in the AMNH's natural history 
exhibit (a ratite-like plume in Cretaceous amber) might have come from, 
if not from a bird.
        I've also heard something to the effect that conifers would have 
been severely vulnerable to being fed upon by dinosaurs, because they 
only put out needles once a year, but yesterday I noticed that on a 
Metasequoia there was what appeared to be new growth coming out. So is 
putting out growth only once a year a specialization of modern conifers 
(perhaps it has something to do with their generally high-latitude 
distribution?) or the primitive condition which Metasequoia appears to 
have evolved away from?
        And these duckbills and ceratopians simply beg the question, yet 
again, why did dinosaurs get so large? Obviously, the environment has to 
select for it. But does the environment no longer select for these kinds 
of giants, or is there simply nothing today living that can respond to 
such selectional pressures the way dinosaurs did?