San Diego Natural History Museum--Your Nature ConnectionSDNHM Exhibits
Featured Dinosaurs
Exhibit Overview
Featured Dinosaurs
Movie Posters
Teacher's Guide
Fun Facts
Featured Kokoro Robotic Dinosaurs

Tyrannosaurus rex

Kokoro Robotic Dinosaur -- Tyrannosaurus rex

Name means: Tyrant lizard king
Time: Late Cretaceous
Locality: North America (Texas, Wyoming, Montana, Alberta, Saskatchewan), Asia (Mongolia)
Size: Up to 49' (16 m) long. Model is 22'8" long.
This carnivore usually grew to around 40 feet tall; some grew to nearly 50 feet. Its four-foot-long head had a mouth full of six-inch teeth. The skeletal structure indicates that it had very powerful jaw muscles and a strong, flexible neck. It probably had extremely good senses of smell and sight; possibly even binocular vision.

Tyrannosaurus rex probably fed on various species of herbivorous dinosaurs. Because of its large size, this animal was too specialized for long-term success as a species. It was too dependent upon large herbivores to feed on, and thus it was less flexible and adaptable than small carnivorous animals.

Name means: Plated lizard
Time: Late Jurassic
Locality: North America (Colorado, Oklahoma, Utah, Wyoming)
Size: Up to 30' (10 m) long. Model is 18'5".
Stegosaurus belonged to an early group of armored dinosaurs. The plates (along with the tail spikes) might have been a protection against attacking meat eaters, but it is also possible that the plates were covered with thin, blood-rich skin and helped the animal regulate its body temperature. It is not known for certain exactly how the plates were positioned in life. The head was relatively tiny, with a brain about the size of a walnut, and there is a large cavity in the hip vertebrae which may have housed a mass of nerve tissue aiding motor control of the huge hind legs. Like many toothless herbivores, this animal may have swallowed stones to help grind up the plants it ate, as do modern-day chickens.

Triceratops Name means: Three-horned face
Time: Late Cretaceous
Locality: North America (Colorado, Montana, South Dakota, Wyoming, Alberta, Saskatchewan)
Size: Up to 30' (10 m) long. Model is 21'4".
The biggest of the horn-faced dinosaurs, Triceratops lived in large herds. The neck frill, unlike that of similar species, was a solid sheet of bone lacking the usual large openings. This probably make the frill a more effective defense against predators, Often the edges of the frill had pointed knobs, and there may have been structural differences in the frill between males and females. The sharp brow horns could have caused considerable injury to an attacking carnivore. Hundreds of skulls and many well-preserved skeletal remains of Triceratops have been unearthed since the late 1800s. They were one of the last species of dinosaurs to live.

Ankylosaurus Name means: Fused lizard
Time: Late Cretaceous
Locality: North America (Alberta, Montana).
Size: Up to 33' (11 m) long. Model is 21'8".
This is the largest known species of these armored dinosaurs, and one of the last of the group to survive right up to the end of the Cretaceous period. It weighed about four tons. The armor plating covering much of its body consisted of many individual plates of bone set close together in the animal's leathery hide, giving it considerable flexibility. When attacked, this creature could probably stand its ground, perhaps squatting down so that only the many spike and plates were exposed to an attacker. Or, if a predator got too close, this animal could swipe at the attacker with its heavy, clubbed tail. Such use of this "bone club" could easily have inflicted serious injuries. The most complete dinosaur skeleton found in California is an Ankylosuar, most likely washed down stream and then fossilized on the ocean floor. Brad Riney, an SDNHM paleontologist, found the remains.

Name means: Parallel ridge lizard
Time: Late Cretaceous
Locality: North America (New Mexico, Utah, Alberta)
Size: Up to 33' (11 m) long. Model is 20'10".
This animal belonged to the hollow-crested group of duck-billed dinosaurs. The nasal passages ran all the way up and down the length of its long, slender head crest, which was sometimes as long as six feet. As in other crested duckbills, the crests probably varied in size between the two genders. The crest could have functioned as both a display structure and as a resonator for horn-type calls. Either way, it would have been an important means of communication. The unique shape of the crest would have given the calls a specific quality, thus helping distinguish the sound from those of other crested duckbills in the forests.

Name means: Winged and toothless
Time: Late Cretaceous
Locality: Europe (England) and North America (Kansas)
Size: Up to 23' wingspan. Model is full scale (23').
Pteranodon is a member of the pterodactyl (flying reptile) family; it was most likely a glider. Its short tailless body was relatively heavy. The function of the great crest on the back of its head is unknown. It could have been an aid for flight, perhaps acting as a stabilizer, or it could have simply acted as an aerodynamic counterbalance to the heavy, elongated head. The jaws are toothless. It probably fed like a modern pelican, scooping up fish in its long, narrow jaws and swallowing them whole.