Polar dinosaurs in Australia?
As a meteorologist, Alfred Wegener was fascinated by questions such as:
Why do coal deposits, a relic of lush ancient forests, occur in the icy
barrenness of Antarctica? And why are glacial deposits found in now sweltering
tropical Africa? Wegener reasoned that such anomalies could be explained
if these two present-day continents -- together with South America, India,
and Australia -- originally were part of a supercontinent that extended
from the equator to the South Pole and encompassed a wide range of climatic
and geologic environments. The break-up of Pangaea and subsequent movement
of the individual continents to their present positions formed the basis
for Wegener's continental drift theory.
Recently, paleontologists (specialists in studies of fossils) have
carefully studied some well-preserved dinosaur remains unearthed at Dinosaur
Cove, at the southeastern tip of mainland Australia. Dinosaurs found in
most other parts of the world are believed to have lived
in temperate or tropical regions, but these Australian species, popularly
called "polar"
dinosaurs, seemed well adapted to cooler temperature conditions. They apparently
had keen night vision and were warm-blooded, enabling them to forage for
food during long winter nights, at freezing or sub-freezing temperatures.
The last of the dinosaurs became extinct during a period of sharp global
cooling toward the end of the Cretaceous period (about 65 million years
ago). One current theory contends that the impact of one or more large comets
or asteroids was responsible for the cooling trend ("impact winter")
that killed off the dinosaurs; another theory attributes the sudden cooling
to global climate change brought on by a series of huge volcanic eruptions
over a short period of time ("volcanic winter"). The discovery
of the polar dinosaurs clearly suggests that they survived the volcanic
winter that apparently killed other dinosaur species. This then raises an
intriguing question: Why did they become extinct if they were well adapted
to a cold climate? Paleontologists do not have the answers. Regardless,
this recently acquired paleontologic evidence convincingly demonstrates
that Australia has drifted north toward the equator during the past 100
million years. At the time when the Australian polar dinosaurs thrived,
their habitat was much farther south, well within the Antarctic Circle.
In 1991, paleontologists discovered the Cryolophosaurus ellioti, a
previously unknown dinosaur species and the only one found on the continent
of Antarctica. Cryolophosaurus fossils were found at Mount Kirkpatrick,
located only 600 km from the present-day South Pole. This newly discovered
carnivorous dinosaur probably was similar in appearance to the Allosaurus
(see artwork above), except for a distinctive bony crest on its head, another
meat-eating species found at Dinosaur Cove, Australia. Studies show that
the Cryolophosaurus lived about 200 millions years ago, when Antarctica
was still part of Gondwana and had a climate similar to that of Pacific
Northwest--mild enough to support large plant-eating animal life, upon which
the Cryolophosaurus preyed. With the break-up of Gondwana, Allosaurus
and Cryolophosaurus parted company, as Australia drifted northward
toward the equator and Antarctica drifted southward to the South Pole.
Had the Australian polar dinosaurs and the Cryolophosaurus been discovered
while he was alive, the embattled Alfred Wegener would have been delighted!
URL: https://pubs.usgs.gov/publications/text/polar.html
Last updated: 12.13.99
Contact: bhanks@usgs.gov
Australian
dinosaurs [155 k]
Dinosaur
Cove [17 k]
"Historical
perspective"