Warm-Blooded "Willo"
Posted May 15, 2000
For many years, paleontologists believed that dinosaurs were nothing more than huge reptiles. In fact, the word dinosaur actually means "terrible lizard." Science
books in the past described dinosaurs as large, cold-blooded creatures that lumbered slowly through the pre-historic past.
In the last 20 years, theories have changed. Most school-aged children (or anyone who saw the Jurassic Park films) have heard it suggested that dinosaurs were
actually warm-blooded creatures, much more similar to birds or mammals than reptiles. Now there is new evidence coming to life to suggest that the dinosaurs seen in the Steven Spielberg's
blockbusters were more fact than fiction in some respects.
Scientists at North Carolina State University have performed computer tomography (CT) scans on a dinosaur fossil. In the past, to look at a fossil, paleontologists
had to actually scrape away all the dirt and rock from the bone. Now, the CT scans allow them to use X-rays to "virtually" strip away layers of the fossil without actually destroying
any of the fossil. With this more delicate procedure, scientists get a clearer picture of the complete specimen.
With CT technology, scientists now can "look into" the entire fossil. What was once thought to be dirt and grime and scraped away, has been discovered to be soft tissue.
Using the CT scans, scientists can now see images of what resembles internal organs.
The 66-million-year-old specimen, nick-named "Willo," was imaged with CT scans, and scientists actually were able to see a heart. Surprisingly, they discovered that
this dinosaur had a heart with 4 chambers, much like that of a warm-blooded mammal or bird. This is the first definitive evidence that suggests that dinosaurs may have been warm-blooded.
Research also indicates that these organisms had a large number of blood vessels – another trait of warm blooded animals.
Reptiles, which only have 3-chambered hearts, are cold-blooded animals. Their circulatory systems differ from those of warm-blooded animals and they have relatively
slow metabolisms. They must rely on the external temperature to warm their bodies. However, mammals and birds, warm-blooded organisms, generate their own body heat and have higher metabolisms.
As a result of this research, there are indications that some dinosaurs may fall into this category.
This new evidence is changing the way paleontologists study dinosaurs. Because new technology has allowed for a more detailed analysis of fossils, scientists hope
to discover how dinosaurs adjusted to changing environments and learn more about how dinosaurs lived.
Activity
Use the Internet sites given here to learn more about dinosaur evolution. With a friend, prepare a class report that explains the difference between warm-blooded
and cold-blooded animals - and how this new data affects theories about how dinosaurs lived.
References
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