Re: Speculative dino species

[Daniel Bensen <dbensen@gotnet.net>]

Morgan Churchill:>>maybe Mosasaurs
invade freshwater enviroments, evolving into forms filling the niches of
todays crocodiles.  Meanwhile, their marine
relative get even more serpentine and sea serpent like.<<
Sea serpent's, maybe, but I think crocodiles were doing a fine job of
being crocodiles, already.  I can imagine mosasaurs evolving into seal
or dolphin-like forms, however, and whales, too.

Andy Farke:>>Perhaps the small aquatic critters niche is
one that the mammals would have successfully exploited.<<
I don't know.  I rather think mammals would still be suited for those
jobs.  Maybe we'd have marsupial otters (such things exist in South
America, anyway) and multicuberculate beavers?

>>So when North and South America
are reconnected, you'd have some pretty major changes in the North
American
fauna. Maybe the end of the therizinosaurs?<<
Never!  Even if the titanosaurs make it all the way up to Alaska, the
therizinosaurs can still run around between the legs of the sauropods,
eating the plowed-up leftovers (the little ones, anyway).

Mike Habib:>>  For example, there would be large
terrestrial prey to be gleaned from riversides in most
parts of the world, so species in the Nile Croc and Saltie
niches might be expected on most continents (at least in
the tropics).<<

>>but I couldn't help toying
with the idea of sanguivorous species of very small
theropods, or more likely, toothed birds (assuming they
make it through K/T as well in our little model).<<
I like the idea of vampire birds.  Actually, they might not be that much
different from the modern ox-pecker, which eats ticks and things living
on large mammals, but also likes to peck at open sores to get at the
blood.

AM Yates:>>Not so, Australia remained partly attached to Antartica which
remained
attached to south America until very late, perhaps even after the K/T.<<

Ah, I stand corrected.  So laellynasaurs could well have migrated to
South America, where they still live, happily feeding around the legs of
the titanosaurs.

Aspidel:>>All right for sauropods eating grasses; then we get grasses
with solid roots!<<
I imaging something like a very tough bamboo.

>>But I'd like not to put grasses in ALL ecosystems: let's try to keep a
good
place for big ferns - still domining in marshes; some
hypsilophodonts get specialized on feeding on ferns, and why not, blue
berries!!<<
I'm thinking about bracken ferns.  I heard somewhere (I think it was a
David Attenburrough (sp?) TV show) that bracken ferns were incredibly
poisonous, and no mammal could eat them.  I recall thinking that the
ferns' extreme toxicity might have been defense against dinosaur
browsers.  Anyway, if the intense browsing of dinosaurs never let up,
bracken ferns might have become far more widespread than they are,
today.

>> or -why not?- the're replaced by giant feathered
dromaeosaurs or coelurosaurs.<<
I like that idea.  Perhaps all the large, carnivorous dinosaurs died out
during the ice age, and all new large forms are giant versions of small
forms.

Christian Kammerer:>>Also, let us not get to reptiliocentric in
our understaning of the oceans--even before the K/T the teleost
radiation
was well underway, and big fishes would likely still be prevalent
(and likely to beat the reptiles to the "whale" ecomorph).<<
Oh, good point.

 Jeff Hecht:>>
What about large aquatic birds? Would they have had any advantages
over the marine reptiles?<<
Well, assuming the Hesperonis didn't go extinct, aquatic birds may have
survived to the present.  I'm not sure, however.  Perhaps every beach in
the world now has a colony of flightless, swimming birds, but I doubt
that they'd radiate into larger niches.