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Re: dino hineys and much more (was mammal mystery)



Dinogeorge@aol.com wrote:
> 
> 
> Elephants and hominids are biding their time, so to speak, until the
> inevitable: Just wait until the next large asteroid impact. Extinction 
> has been the historical fate of all but two genera of elephants and all 
> but one genus of hominid.

And of all of the dinosaurs and of all of the trilobites and of all 
pelycosaurs and of all . . . . Vulnerability to extinction does not 
equate to the success of a genus, in my opinion. All species eventually 
become extinct, and that extinction does not necessarily equate with 
failure.

 But elephants and hominids aren't doomed >because< there
> are no mouse-size elephants or hominids. They're doomed because, unlike
> small, fecund animals, elephants and hominids are unlikely to give rise to
> new species quickly enough in response to a relatively rapid unfavorable
> environmental change. Even if there >were< mouse-size elephants and hominids,
> the larger members of those families would still be doomed when such an
> environmental change occurred. They would, however, likely be replaced by the
> larger descendants of their smaller relatives once the environment
> restabilized.

Completely true, but I wonder about the context of this statement.

Was the Mesozoic the "Age of Shrews" because those dinosaurs that were 
exploiting just about every econiche failed to realize that they should 
have sat tight in burrows eating grubs, breeding wildly and waiting for 
the next asteroid . . . and then the next . . . and then the next . . . ? 
Do hundreds of millions of years of successful radiation (leading to 
"dooming" specialization) mean that the dinosaurs were not successful 
during those same hundreds of millions of years?  I don't think that you 
really believe this.  Of course I agree that many animals are victims of 
their success in the final analysis, but that observation doesn't really 
have a place in a discussion of the relationship between Mesozoic mammals 
and the dinosaurs. 

Let's not forget that the origin of this post was the question "why were 
mammals small and dinosaurs large?"  Can anyone seriously argue that the 
mammals "chose" to be small because they were little versions of 1950's 
paranoids, building their little bomb shelters because they "knew" an 
asteroid was coming? Or that the dinosaurs shrugged, their "primitive" 
bipedalism handicapping them from taking the coveted burrowhole, and 
sadly trooped off to settle for the rest of the terrestrial world?  Of 
course not!  Animals radiate into every niche they can.  Mammals were 
kept in a few marginalized niches because the dinosaurs were better 
suited at that time to the multitude of other niches.  Note also that 
those clever furballs either forgot their tininess strategy when the 
dinosaurs were gone or someone forgot to tell Indricotherium.

Two postscripts:

1) To the original poster:  don't forget that there were many small 
dinosaurs too.  Compsognathus and others were very small -- smaller than 
many of today's mammals.  Those small dinosaurs may have eaten the little 
mammals when they could catch them, possibly aided by the ability to 
catch prey with their forelimbs.

2) As for questions about the "warmness" of mammals' little hineys (some 
took this to suggest that dinosaurs had cold hineys, and were outraged), 
the jury is still out on dino hineys.  Until we know more about their 
hineys, we can only speculate.  But we know that mammal hineys are warm 
(mine is, anyway).

Ta for now --

Larry