(Copyright Michael Skrepnick, 1998)

The Dinosauria:

Truth is Stranger than Fiction

Dinosaurs occupy a vaunted niche in the public mind; the very word conjures up images of gargantuan, now-defunct beasts that ruled the Earth long ago, holding a reign of terror for some 160 million years, and then mysteriously vanishing with only their titanic bones as evidence of their existence. "Dinosaur" reaches deep into our psyche and drags out nightmares from culturally-embedded monster myths. What is the truth about dinosaurs that underlies the popular awe and mystique that shrouds them? What does modern science have to say about the dinosaurs? Are they truly obsolete, long-extinct relics of a more primitive and experimental stage in the history of life, or is there more to the Dinosauria than meets the eye?

Dinosaurs are animals that evolved into many sizes and shapes. Dinosaurs were and are quite diverse, and often one person will think of an animal like a long-necked sauropod, while another person will think of a large, fierce meat-eater like Tyrannosaurus rex. It should be clear then that the term "dinosaurs", or the scientific version "Dinosauria", is describing a diverse group of animals with widely different modes of living. The term was invented by Sir Richard Owen in 1842 to describe these "fearfully great reptiles", specifically Megalosaurus, Iguanodon, and Hylaeosaurus, the only three dinosaurs known at the time. The creatures that we normally think of as dinosaurs lived from late in the Triassic period (about 225 million years ago) until the end of the Mesozoic era (about 65 million years ago); but actually they live on today as the birds.

Running Deinonychus, copyright B. Cunningham 1995

DISPELLING DINOSAUR MYTHS

The term "dinosaur" has had a long history of misrepresentation. A few simple points must be kept in mind when discussing these animals:

Not everything big and dead is a dinosaur. All too often books written for a popular audience include animals such as mammoths, mastodons, plesiosaurs, ichthyosaurs, and the sail-backed Dimetrodon. Dinosaurs are a specific subgroup of the archosaurs, a group that includes crocodiles and birds, whereas mammoths and mastodons are mammals. Other archosaurs included the pterosaurs, relatives of dinosaurs but not true dinosaurs. More distantly related to true dinosaurs were the marine plesiosaurs and ichthyosaurs. These were marine reptiles, not dinosaurs or even close relatives of them. Dimetrodon is neither a reptile nor a mammal, but a basal synapsid -- that is, an early relative of the ancestors of mammals.

Not all dinosaurs lived at the same time. Different dinosaurs lived at different times. Despite the portrayals in movies like Fantasia and Jurassic Park, no Stegosaurus ever saw a Tyrannosaurus, because Tyrannosaurus wasn't alive for another 80 or so million years. Ditto for Apatosaurus (a.k.a. "Brontosaurus").

Dinosaurs are not extinct. Technically. Based on features of the skeleton, most people studying dinosaurs consider birds to be dinosaurs. This shocking realization would make even the smallest hummingbird a legitimate dinosaur. Rather than refer to "dinosaurs" and birds as discrete, separate groups, it is best to refer to the traditional, extinct animals as "non-avian dinosaurs" and birds as, well, birds are birds, or avian dinosaurs. Whatever works for you. It is incorrect to say that dinosaurs are extinct, because they have left living descendants in the form of cockatoos, cassowaries, and their pals -- just like modern vertebrates are still vertebrates even though their Cambrian ancestors are long extinct. Yes, even birds have ancestors, funny looking as birds may be.

Click on these buttons to learn more about dinosaurs

Select Systematics to learn about specific dinosaur groups!

Go to the Dinosaurs in Cyberspace: Dinolinks

Early Dinosaur Discoveries in North America

UCMP Special Exhibit: Dinobuzz

Explore current and exciting research into the biology of dinosaurs. Were they warm-blooded? Why did they go extinct? Are dinosaurs related to birds, or are they reptiles (or are both true)? All this and more!

UCMP Special Exhibit: Dilophosaurus!

Visit a very special account of the discovery and reconstruction of this dinosaur. The exhibit is narrated by UCMP's own Sam Welles, who discovered Dilophosaurus!

UCMP Special Exhibit: T. rex Expo

No dinosaur is so famous nor so feared as Tyrannosaurus. UCMP assembled this exhibition in conjunction with the unveiling of its free-standing skeletal mount.

Sources and Suggested Further Reading:

Weishampel, D.B., P. Dodson, and H. Osmolska (eds.). 1990. The Dinosauria. University of California Press: Berkeley. 733p. Simply put, the definitive text on dinosaurs. A bit technical for beginners, but exhaustive in detail; a "must have".

Norell, M.A., E.S. Gaffney, and L. Dingus. 1995. Discovering Dinosaurs at the American Museum of Natural History. Nevraumont Publishing Company, Inc.: New York. 204p. A current update of dominant thinking in dinosaur paleontology. Targetted for the layperson (with a good review of cladistics), but useful for all.

Norman, D. 1985. The Illustrated Encyclopedia of Dinosaurs. Crescent Books: New York. 208p. 10 years after its release, still the best popular book on dinosaurs, for all ages.

Padian, K. and D. Chure (eds.). 1989. The Age of Dinosaurs: Short Courses in Paleontology Number 2. The Paleontological Society. 210p. A book outlining for teachers how to run a course about dinosaurs.