Re: new boook on functional morphology

[Stan Friesen <swf@ElSegundoCA.ATTGIS.COM>]

From: JCMcL <darwincr@laplaza.taos.nm.us>
 > 
 > > What I am opposed to is the old picture of a solitary Triceratops
 > > having a duel with a Tyrannosaurus.  I doubt that a Tyrannosaurus
 > > would confront a healthy adult Triceratops from the front under
 > > normal circumstance.  
 > 
 > I rather doubt that a healthy Triceratops could be found in a solitary 
 > condition.  I also doubt that anything hunting such animals would do so 
 > in a solitary manner.

That too.
 > 
 > > Note, in one reference I have a case is made that dinosaurs, even
 > > the large ones. were r-selected, rather than K-selected like large
 > > mammals.  If this is really so, than it may never have been the case
 > > that protecting young was economically viable (individual young are
 > > not as valuable to a r-selected animal, and so are less often protect > > 
 > My own suspicion is that, as in, say, ostriches, the dinosaurs were 
 > R-selected as eggs and K-selected as chicks ...

Or, mor precisely, a hybrid stategy. 
 > 
 > In a world full of small fast predators, an unprotected ceratopsian 
 > "saurlet," as 
 > I've said earlier in these postings, would be topsy mcnuggets to such 
 > predators.  Small, fat, squishy.  MMMMmmmmmm!  If the parents simply 
 > abandoned such tasties to Cruel Father Nature, the ceratopsians would 
 > likely have been a short-lived phenomenon.

If enough are produced, the predators either become saturated, or
a few survive purely by chance.  In the more extreme r-selected species,
like many corals, fewer than 1 in 10,000 hatchlings survive to reach
maturity.

Now, dinosaurs could not match the level of egg production seen in such
animals, but a ceratopsian could still lay some 20 or so eggs per year,
over a lifespan of several decades.  This comes out to hundreds of
hatchlings.  All that is necessary for effective reproduction is that
*two* of these survive to adulthood.

On the other hand, the evidence from the Texas Chasmosaurus
mass-death site is that ceratopsian herds were mixed-age, ranging
from very young to full adult.  his suggests parental care, and
supports mixed-strategy reproduction in at least Chasmosaurus.
.  
 > 
 > Nonetheless, the straight-ahead horns and other offensive-defense 
 > elaborations so common in the ceratopsian theme argue, at least to me, in 
 > favor of some very impressive selective factor other than head-butting, 
 > expecially since it appears in both sexes.  
 > 
The last is not conclusive.  Many antelope have horns in both sexes,
despite them being used mainly by the males.  Also, shoving is more
likely than butting - there is less likelyhood of serious injury.

swf@elsegundoca.attgis.com              sarima@netcom.com

The peace of God be with you.