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RE: Floating allosaurs?? (sort of...)



Terrestrial animals that make it to remote islands like the Galapagos are
good example - the best current theory is that the got there by riding
natural rafts of storm debris (fallen trees etc.).   The number of founding
individuals is estimated to be very small, because it is a freak random
event that any make it all all.   

Until driven extinct in the 19th century, there were many islands with giant
tortises besides the Galapagos - particularly in the Indian Ocean.  The
island of Aldabra still has them.   Tortises seem to raft well, and can
survive without water for a while which makes them good candidates.  

Birds are easier to get because even small birds not accustomed to long
distance flight can be blown hundreds of miles in a hurricane or other large
storm.  Most remote islands without normal compliment of terrestrial fauna
develop large flightless birds - of which the hapless Dodo of Mauritus is
the most famous example.  Hawaii had a similar giant flightless goose.

Dinosaurs would be hard to raft, but could get stranded on an island if sea
level changes or subsidence separate it from the mainland.  They could also
swim or float across small distances.  Recently there was a report of two
moose seen swimming between islands in Alaska - one was killed by a pod of
orcas.

It seems virtually certain that islands like this existed during the
Mesozoic which could have supported unusual kinds of dinosaurs (or maybe
just more tortises).  Very remote islands - say a thousand miles or more
from a continent (analogous to Hawaii) would have mostly airborne residents.
Maybe someplace a flightless pterosaur evolved!   Islands that are closer to
a continent - say a few hundred miles (analagous to Galapagos, Aldabra...)
probably had tortises, lizards and perhaps small dinosaurs.  Ocean currents
can make a difference in distance of course - it is not just distance, but
the easy of rafting/floating/swimming that counts.  Islands that are close
to a continent - say a few tens of miles - might have some larger dinosaurs.


Nathan