Teacher's Guide T. REX banner

Evidence Presented in the Exhibition

Throughout the exhibition, evidence is presented to show how paleontologists use fossils to hypothesize the appearance and lifestyle of prehistoric animals.

Kokoro photo of T. rex head

Carnivorous animals usually have sharp teeth and claws. Sharp teeth are useful for killing another animal or tearing the flesh from one that is already dead. Long arms with claws are useful for grasping live prey. T. rex had teeth that were long, curved, and sharp. Although T. rex had claws, its arms were extremely short and probably useless for grasping and holding.

Information about posture and rate of locomotion comes from studying vertebrae and leg bones. For instance, a long tibia (shin bone) compared with the femur (thigh bone) indicates an animal designed for speed. Animals that have a tibia and femur of about equal length are probably slower, or endurance runners. Scientists study vertebrae and their projections to determine the size of attached muscles that, in turn, indicates in what position the head and tail were held. Observation of the skeleton of T. rex shows an animal with a center of balance over its hind legs, using its head and tail for counterweights. With a tibia and femur of about the same length, we could guess that T. rex was a slow runner.

Predator Attributes:
   • fast runner
   • great agility
   • grasping arms
   • curved claws
   • stereoscopic vision
   • excellent eyesight

Scavenger Attributes:
   • walker
   • limited agility
   • useless arms
   • large body size
   • powerful jaws
   • excellent sense of smell

The size and position of openings on the skull for eyes, ears, and nose provide clues about an animal's senses. For instance, relatively large eyes (shown by large eye sockets) might be useful for hunting at night; whereas smaller eyes might indicate that the animal was active during the daytime. Eyes positioned close together at the front of the head often work together (stereoscopic vision) to provide depth perception--an arrangement useful for predators. Prey animals generally have eyes located on the sides of the head allowing for a wider field of vision. Evidence presented in the exhibition indicates that T. rex had rather small eyes positioned close together. Would this indicate that T. rex was a daytime predator?

Examination of the brain case shows that T. rex had a very large olfactory nerve, or a good sense of smell--perhaps useful for locating dead and decaying animals.

Fossilized dinosaur dung provides clues about a dinosaur's diet. For instance, the dung may contain the remains of plants or bits of bone. The trick, of course, is to identify which dinosaur made the dung. A large coprolite (fossil feces) has been found that may have been made by T. rex.

At the end of the exhibition, several carnivorous dinosaurs are pictured along with a summary of scavenger and predator attributes. Viewers are asked to consider the evidence for each dinosaur and to decide whether it was guilty of murder (a predator) or should be acquitted (a scavenger). Visitors vote by dropping a coin into a designated plastic tube.

Photo © 2002 Kokoro Dinosaurs
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