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Dino migration



My 2 cents (more questions than answers).

Behaviors don't fossilize.  Given that:

1) If a dinosaur is widespread over a geographic area in a particular
period of time, how does one tell if it is migratory from one end of the
region to the other or not? In what distribution pattern would the
fossils be found to eliminate non-migratory alternative explanations?

2) If a dino is found in only 2 discrete locations, say 500 miles apart,
how can one tell the difference between these 2 scenarios: a) 2 distinct
population centers of one species isolated geographically, perhaps on the
verge of becoming separate species, and b) one species that has a
breeding and a non-breeding region, and that species migrates between
them?

3 )How can one tell the difference between a well-used game trail and a
migratory route?  Two way tracks won't tell you anything -- these kinds
of tracks lead to and from water sources all the time today.  Also, many
migrating animals use 2 different routes up and back during migration.

4) Herding and migration don't necessarily correlate; it depends on what
you mean by herding [flocking].  When small songbirds migrate, they
concentrate in flyways and travel together, but is it just because they
all seek the same shelter, cover and food, or do they seek each other
out?  Do the weather and wind patterns force them together?  If dinosaurs
migrated, would the same be said about them?  How could you tell the
difference between fossils of a plain herd of dinosaurs dying in a storm
or flood and a migrating herd dying in the same situations?

5) Hawks concentrate during migrations not because they seek each other
out but because they seek thermals and their prey, both of which
concentrate over certain geographic areas and in flyways.  I don't think
any one considers hawk migrants as "flocking."  Dino predators may have
acted the same.  If some disaster befell predatory or scavenging
dinosaurs in a large concentration, how can you tell they were migrating?
Their prey were migrating?  Their prey were just gathering to court and
mate?

Is their *any* unambiguous evidence of migration in dinosaurs, and what
is it exactly?

Judy Molnar
Education Associate, Virginia Living Museum
vlmed@juno.com
jamolnar@juno.com
All questions are valid; all answers are tentative.

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