DINOSAURS ARE A THING OF THE PAST
by Whit Gibbons
December 30, 2007
change has been increasingly in the news recently. (The Nobel Peace Prize
is a sure-fire attention-getter.) Among the species that receive special
notice when global climate change is discussed are polar bears. They are
unique among bears in being the only solid white species. The adult bears
are majestic and photogenic. The babies are cute and photogenic. The species
is a natural in the role of poster child for the adverse effects of global
climate change. Penguins, the celebrity species of the South Pole, are
also indicators of what we could lose from the impacts of global climate
of creatures lived in those icy climes back before humans inhabited the
earth? We know that dinosaurs lived in temperate and tropical areas across
the world. But what about the polar regions? Did dinosaurs live at the
poles in the cold and darkness that would have prevailed?
The short answer is "yes," dinosaurs lived in both northern
and southern regions that were decidedly colder than places where most
reptiles live today. Fossil records from Alaska, southern Australia, and
even Antarctica have revealed that about 100 million years ago, dinosaurs
roamed the polar landscape. Interpreting what their lifestyles were involves
a mix of geology, paleontology, and ecology, along with meteorology, physiology,
and several other scientific fields. Even with the tools of modern science,
many mysteries remain about these fascinating animals.
The importance of geology in reconstructing what animals lived where relates
to where Antarctica and Australia were a million centuries ago. Geological
history tells us that at that time these continents had not split apart;
they were a single cold continent centered around the South Pole. Later,
of course, Australia would break away, drifting northward toward the equator.
However, back then dinosaurs, whose fossil bones have been found in the
southern part of Australia, lived in a land of ice and snow far different
calculations have been made of the age of the rocks where fossils have
been found and where continental drift would have placed the world's land
masses at the time. Scientists known as polar dinosaur hunters have also
incorporated the tilt of the earth relative to the sun in estimating what
conditions were like in winter and summer. Most agree that weather conditions
were probably like parts of Alaska are today, with frequent below-freezing
weather and half a year or so of winter darkness.
Part of the biological mystery is determining how a reptile could survive
such conditions. Being warm blooded (technically, being an endotherm and
producing heat internally) like polar bears and penguins would be one
solution for living in such a climate. Some paleontologists believe that
the closest relatives of dinosaurs were birds and that they were indeed
warm blooded. However, being cold blooded (technically, being a poikilotherm
and getting body heat from external sources) permits some modern reptiles
to hibernate for several months without food or water. Also, the enormous
leatherback sea turtles have been known to travel into the ice-cold waters
of polar seas, indicating that large reptiles the size of small dinosaurs
can survive at least short periods of polar weather.
proposal has been that the large dinosaurs living near the poles migrated
toward more temperate climates during the winter, the way many birds and
whales do today. With the paleontological evidence available today we
can only speculate about how these animals survived cold winters. But
just knowing that dinosaurs were present in cold climates as well as warm
ones stirs the imagination.
So if polar dinosaurs once ruled the poles but are now extinct, why should
we be concerned about other species disappearing? Because polar bears
and penguins have evolved alongside us. They help make today's world what
it is. They are not species of the past that we know only from fossils.
Whatever caused the dinosaurs to disappear, it had nothing to do with
the human race. The same cannot be said for any species that exists today.
should vow to try our best to prevent any other species, plant or animal,
from going extinct on our watch. That would be a worthwhile New Year's
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