Re: Dinosaurs vs. mammals: a hypothetical scenario

["Scott" <hmwh@comcast.net>]

Are deciduous trees delicious to a sauropod, especially leafless? Probably 
some sort of migratory behavior would become necessary for any wormholes 
that led to a temperate zone. How long does it take for a nonmigrator to 
become a migrator?

Cunning egg-sucking vermin, some of them mammals. Makes me wonder how many 
nonavian dinos would  produce a next generation.

Scott Perry
High Mountain Writers' House

----- Original Message ----- 
From: "Brian Lauret" <zthemanvirus@hotmail.com>
To: "the list" <dinosaur@usc.edu>
Sent: Thursday, April 07, 2011 11:38 AM
Subject: Dinosaurs vs. mammals: a hypothetical scenario



For those among us who are not particularly interested in untestable what-if 
scenarios, this is probably a good topic to ignore. Its subject will be 
completely hypothetical. To those who are interested in this, however, I 
hope my question will be fun and interesting.

I wonder how non-avian dinosaurs would fare in Cenozoic, mammal-dominated 
ecosystems, especially in one at its (of course subjective) prime with 
reasonable stability and at its maximum number of niches. Because modern day 
ecosystems are generally depleted compared to their prehistoric 
counterparts, I'd like to take the late Miocene during which mammal 
diversity in terms of species richness may have peaked or was very high at 
the least, as our setting.

So I would want to take late Miocene ecosystems and let them be invaded by 
late Cretaceous, say Campanian, dinosaurs, via some sort of wormhole or the 
like that would allow Campanian dinosaurs from all over the world to invade 
late Miocene ecosystems all over the world. So Campanian Australian 
dinosaurs end up in late Miocene Australia, Campanian Asian dinosaurs end up 
in late Miocene Asia and so on.

What I wonder is, would those dinosaurs be competitive in their new setting? 
I personally suspect they might well be because of their fecundity, probably 
efficient metabolism, ability to quickly consume large amounts of  low 
quality food and likely adaptability.
This, I think, would be especially true of the larger dinosaurs. I'm pretty 
sure an adult titanosaur would be safe from even the largest, most powerful 
late Miocene predators such as percrocutids or barbourofelids. The same 
might apply to large ornithischians such as ankylosaurs and giant 
hadrosaurs. Their size, strength, thick hide and weaponry would probably 
make them (all but) immune to pesky mammalian Miocene carnivores.

I'd also think large theropods would become contenders for the title of 
worst invasive exotic ever. Given the size and strength of an adult 
tyrannosaur, it could probably easily hunt even the largest landliving 
mammals around.

Probably, smaller dinosaurs versus mammals would be where things get more 
interesting. For example, would a population of alvarezsaurs or a 
leptoceratopsids survive in an ecosystem with boreophagines and sabertooth 
cats? Would they prove competitive against pangolins or pigs? Would smaller 
ornithopods be able to compete against horses or ruminants? Would 
dromaeosaurs be able to compete with hyenas?

I'm very interested in your thoughts on what you think would happen in such 
a scenario.

Thanks in advance,

Brian