Recent Dinosaur Fossils Contribute to Understanding the History of Life
Posted January 21, 1999
By Alton L. Biggs
Dinosaurs have captured the interest of people since the first fossils of them were found. Ask any elementary school student about dinosaurs and you will likely be
told the names of a variety of species, where and when they lived, as well as what their behavior might have been. But have we found out all we can about dinosaurs?
A revolution in our understanding of dinosaurs began in the 1970s. It was first suggested at that time that dinosaurs were active, warm-blooded animals very unlike
the dull, sluggish animals theyÕd been thought to be.Public interest in the dinosaurs reached new highs when the movie Jurassic Park appeared in movie theaters. Today, research into
dinosaur behavior, physiology, and phylogeny continues at a rapid pace.
Late in 1998, for example, a new species of dinosaur that mimicked crocodiles was discovered in Africa. At the same time, a huge trove of dinosaur eggs - some even
including fossilized embryos and patches of skin - was found in South America. Although our understanding of the history of life will never be complete, it is becoming clearer because
of fossil discoveries all over the world.
Dinosaurs as Crocodile Mimics
It is becoming increasingly difficult to categorize dinosaurs because discoveries are showing that they possessed tremendous variety. Although Tyrannosaurus, Allosaurus,
and Velociraptor are probably the best known of the big predatory dinosaurs, there were many other kinds. One little-known group, Spinosaurus, consists of only three known
species.
The first specimen of this group was discovered in Egypt. It was believed to have had a sail running down its back, an adaptation that may have been the result of
changing from a diet of meat on land to one of fish in water. Another similar species is known from a few fossils in Brazil. In November of 1998, a new species was described by Paul
Sereno and several of his colleagues from fossils found in Egypt.
Suchomimus tenerensis, was the name given to this new discovery. Unlike other more familiar predators, this dinosaur did not feed primarily on land.
Suchomimus, or "crocodile mimic", prowled water up to two meters in depth in search of fish, its primary prey. Weighing in at 4 metric tons Ñ about the same weight of Tyrannosaurus
- this dinosaur had powerful forelimbs, a long flexible neck, and jaws more than a meter long but only about ten centimeters wide. Like other spinosaurs, Suchomimus had a small
sail that may have helped it as it swam in search of prey. It seems that there is still a great deal more to be learned about life in the Mesozoic.
Dinosaur Eggs and Embryos
With almost every new fossil, exciting new details are revealed. This is as true today as it was a hundred years ago. Within a few weeks of the news of Suchomimus,
another important dinosaur fossil find was announced from Argentina by National Geographic scientists. In an area that had been flooded about 75 million years ago, they found a large
dinosaur nesting area containing thousands of pieces of dinosaur eggs, partial skeletons of baby dinosaurs, and even some fossilized dinosaur skin. The 45-foot-long dinosaurs that made
the nests were Titantosaurus, close relatives of Brontosaurus now known as Apatosaurus.
When the team of scientists returns to the area, they hope to answer even more questions about these creatures. For example, they may be able to find enough fossils
to reconstruct a series of eggs from early embryo stages to hatchlings. Clues about the behavior of these dinosaurs are also likely to be found. As one of the teamÕs scientists said,
"You never know what you'll find the next time you look." Whatever they find, it will almost certainly be new and important.
Activity
Interview three elementary students to find out what they know about dinosaurs. Record the information they provide. Use the Internet, your textbook, and recent
magazine articles to locate additional information about recent dinosaur discoveries and what the discoveries may suggest about evolutionary history. Present your findings to the class.
Compare information from your different sources. Include photos or drawings to illustrate your presentation. Also, describe which findings you feel have the most significance for future
understanding of dinosaur evolution.
References
"A Long-Snouted Predatory Dinosaur from Africa and the Evolution of Spinosaurids." Paul C. Sereno, Allison L. Beck, Didier B. Dutheil, Boubacar Gado, Hans
C. E. Larsson, Gabrielle H. Lyon, Jonathan D. Marcot, Oliver W. M. Rauhut, Rudyard W. Sadleir, Christian A. Sidor, David D. Varricchio, Gegory P. Wilson, and Jeffrey A. Wilson in Science,
Vol. 282, pages 1298-1302, 13 November 1998.
"Sauropod Dinosaur Embryos from the Late Cretaceous of Patagonia." Luis M. Chiappe, Rodolfo A. Coria, Lowell Dingus, Frankie Jackson, Anusuya Chinsamy, and
Marilyn Fox in Nature, Vol. 396, pages 258-261, 19 November 1998.
"Popular Interest Fuels a Dinosaur Research Boom." Erik Stokstad in Science, Vol. 282, pages 246-247, 13 November 1998.
Web Sites
|
