Re: Big = Old = Advanced?

[John Bois <jbois@umd5.umd.edu>]

Fri, 22 Aug 1997 Dinogeorge@aol.com wrote:
> << Dinogeorge@aol.com wrote:
>>> Large animals needs lots of territory, and have smaller populations,
>>> longer
>>> gestation and/or growth-to-maturity periods, and smaller
>>> litters/hatchings.
>>> All these factors place clear limits on their potential for
>>> diversification.

Betty C. replied:  
>  But dinosaurs are KNOWN for their remarkably large clutches.  

Dinogeorge responded:
> I don't think those clutches are remarkably large. Indeed, they're not
> unreasonable at all, given the sizes of the adults. 

John Bois now chimes in:
While I agree wih Dinogeorge's main point (taxa that lose small
species become extinct), I take issue with this mechanism.  Creatures lay
or deliver the maximum number of offspring they can as long as those
offspring have a reasonable chance of success--excess capacity, then,
would be better used for future reproduction or assuring greater success
of current production (parental investment). One would think a saurapod
could lay much bigger clutches (and, therefore call 18 a small number).
But, given that fecundity determinants of those creatures were unique and
unknown, claims of relative size are meaningless.  What we can say, and
Greg Paul has said it, is that if all the offspring of a saurapod
survived she would have  produced upwards of 400 adult saurapods in her
life. Obviously, as Betty C. and Tracy Ford have noted, there is gross
culling going on. Laying more eggs would seem to be a fruitless
enterprise.  
        In addition to this, size _per se_ has nothing to do with
clutch/litter size.  Compare Emperor penguin (3 ft. long and lays one egg)
with Bob-white Quail (11 in. long and lays up to 28 eggs).  Or Elephant
(big and one offspring) with House Mouse (small with up to 11 offspring).
        Anyway, it doesn't seem we can even say categorically that there
_were_ no small dinosaurs at the K/T just because we haven't found them.
This is especially true since their bones would have been in exactly the
same place as the stealthy nests we also haven't found, i.e., in dense
fossil corroding cover.
        So there!