Re: Dinosaurs survived in Antarctica? (Was: Re: "Dinosaurs Died Within Hours After Asteroid Hit Earth...")

[Tim Donovan <uwrk2@yahoo.com>]

--- Michael Kaib <michael@kaib.org> wrote:
> It
> is an interesting 
> hypothesis, that they could have survived the K-T
> border in Antarctica 
> for possibly many million years. Due to the sparse
> known fossil record 
> up to now I wouldn't know how to disprove this
> without more intensive 
> local research. 

  If dinosaurs survived in Antartica, they probably
would have migrated to South America, Australia and
Madagascar. IIRC mammals reached Antarctica from South
America around K-T time, and went on to Australia.



Of course surviving dinosaurs had
> become extinct by 
> Antarctic climate cooling down, latest by the total
> glaciation in 
> Oligocene - an often undervalued mass extinct where
> all Antarctic 
> species lacking good swimming or flying capabilities
> became extinct - 
> maybe including real non-bird dinosaurs.
> 
> At the K-T border the Antarctic climate was
> doubtless the globally most 
> extreme. Hence the special Antarctic climatic
> conditions might have 
> given Antarctic habitants a higher probability to
> survive the mass 
> extinct. E.g. darkness lasting several years as
> recently postulated 
> would not be very unusual for an Antarctic
> population. The Antarctic 
> survival hypothesis could be a challenging
> motivation for further 
> Antarctic research.
> 
> However, for birds a very important reason for their
> K-T border survival 
> until today could be their capability to fly long
> distances. They were 
> easily able to escape even rapid climatic changes by
> moving to habitable 
> zones in far regions, even on other continents. This
> was rarely possible 
> for land animals without flying or large distance
> swimming capability, 
> since at this time the land consisted of 7 isolated
> continents 

  I don't think so. Saurolophus and tyrannosaurs
radiated across the Bering bridge in the
Maastrichtian. There was a report that Betasuchus, in
Europe, resembles Dryptosaurus from eastern North
America.



and many 
> large islands without land bridges. For
> long-distance swimmers like some 
> crocodiles, swimming could have been a similar
> successful survival 
> strategy in this global crisis.

  That depends on how cold the seas were.



 But it seems that
> crocs had a better 
> strategy, because they were nearly untouched by the
> event. For some 
> small mammals and lizards alternative survival
> strategies were more or 
> less successful, as discussed above. This Antarctic
> survival hypothesis 
> still leaves some open issues: Why became pterosaurs
> and plesiosaurs 
> extinct? 


 Unlike crocodiles, they couldn't hibernate, and both
may have been too dependent on marine productivity.
Dyrosaurs inhabited estuaries and survived.


May be there is a different answer for
> them.
> 
> On the other hand, a global fire as postulated by
> Robertson sounds 
> curious for me. I've read about recent research
> restricting the fire 
> zones to less than 1000 km. And if there were a
> global fire why not in 
> Antarctica? 

  Heavy rainfall? But rain is most likely anywhere
there is the greatest concentration of forest or
vegetation, hence dinos.



For me the reason for the extinction
> should to be a period 
> of more complex rapid climatic changes. However, the
> latter survival 
> strategies might have been important. I still search
> for a simple 
> hypothesis explaining
> -    extinct of (non-flying) dinosaurs, plesiosaurs
> and pterosaurs
> -    reduction of mammals, birds and lizards to few
> small species

  I don't think lizards were much affected, nor
turtles.


> -    leaving crocodiles nearly untouched
> at the K-T border. What happened to the other sea
> fauna, insects or flora?
> 
> Yours,
> Michael Kaib
> Munich, Bavaria
> michael@kaib.org
> 
> 



                
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