Geoscience Reference
In-Depth Information
By the time I arrived in Australia—more than 25 years later—it was still the
only undisputed dinosaur track in all of southern Australia. I had found some not-
so-clear dinosaur tracks only a few months before at another spot, but it was time
to find more. Thus, the purpose of our troublesome foray that day was to revisit the
source of that track and look for more dinosaur tracks. Pat and Tom, still filled with
thewisdomimparted byKnowledgeCreekthedaytheywenttherein1980,hadde-
clined our invitation to come along.
Dinosaurboneswererelativelyrareinthispartoftheworldand,mostinterest-
ing, represented a polar dinosaur assemblage. Based on plate-tectonic reconstruc-
tions, the rocks in this part of Australia were originally formed near the South Pole,
when southern Australia was connected to Antarctica during the Early Cretaceous
(130-100
mya
) before drifting north to its present location. Nearly all of the dino-
saur bones and teeth in strata there were from small dinosaurs, and most of these
were hypsilophodonts. Only a few pieces were from theropods, such as one bone
thatcamefromadinosaursimilartotheLateJurassic
Allosaurus
ofNorthAmerica.
Hence, Pat and Tom often asked themselves, “Why hypsilophodonts?” and
wondered how these ornithopods, which were probably too small to migrate, had
adapted to long, cold, dark winters of polar environments during the Cretaceous.
In a paper they and other co-authors published in the journal
Science
in 1988, they
proposed that hypsilophodonts and other dinosaurs in the region were likely endo-
thermic, or “warm-blooded,” generating their own body heat. At that time, warm-
blooded dinosaurs were still being hotly debated (no pun intended), and recall that
Robert Bakker's
The Dinosaur Heresies
had only been published two years before
then. Not all paleontologists were so accepting of the idea that dinosaurs were less
like reptiles and more like birds, and others thought that maybe dinosaurs represen-
ted something entirely different from either group of modern animals.
PatandTom,alongwithmanyothercontributorstotheirpaper,fedthisdebate
further by documenting the best-known polar dinosaur assemblage in the Southern
Hemisphere. This added support to the then-remarkable idea that dinosaurs lived in
