Rock Cycle - Past Life (KB)
 Lab 

   
OBJECTIVES:
  • Distinguishing dinosaur meat-eaters from dinosaur plant-eaters.
  • Comparing tooth shapes.
VOCABULARY:
  • carnivore
  • herbivore
  • omnivore
MATERIALS:

Students use models to determine herbivores and carnivores.

BACKGROUND:

Paleontologists rely on several different types of fossil clues to interpret the eating habits of extinct animals, including dinosaurs. Teeth are the best clues to determine what dinosaurs ate. Dinosaurs with sharp, pointed, serrated teeth throughout their mouths, like Tyrannosaurus, Allosaurus ,or Coelophysis, ate meat. Their teeth acted like built-in steak knives for slicing soft flesh. The plant-eating dinosaurs had flatter, wider teeth for grinding up tough plant material. The duckbilled dinosaurs (the hadrosaurs) were one type of plant-eating dinosaur. Some of these had thousands of teeth in their mouths for grinding vegetation. Even with many teeth, some of the herbivore dinosaurs weren't able to grind plant material well enough in their mouths to be able to digest it. Some of them swallowed stones, called gastroliths, that stayed in their digestive tract to help pulverize food after it was swallowed. There were also omnivorous (both plant- and meat-eating) dinosaurs that had teeth that were intermediate in shape, between those of the carnivores and those of the herbivores.

Dinosaur posture is also a clue to food type. All of the carnivorous dinosaurs were bipedal (walked on two legs), while all of the herbivorous dinosaurs were either quadrupedal (walked on four legs) or spent some time on two and some time on four legs. Physical characteristics are also clues to dinosaur eating habits. Carnivores had large, sharp claws. Herbivores commonly had armatures such as horns, bony skull frills, plates, thickened bones, or tail/thumb spikes for protection. Carnivores had little or no armature, probably because it would have slowed them down in their pursuit of prey.

This lab reviews the difference between carnivores and herbivores. Students will learn to tell the differences between them by recognizing key physical traits.

PROCEDURE:
  1. Explain to the class that we can make very good guesses about what different dinosaurs ate by looking at the shapes of their teeth and bodies. Dinosaurs with sharp, pointed teeth that walked on two legs were carnivores (meat-eaters); dinosaurs with flatter, grinding teeth that walked on four legs (all or part of the time) were plant-eaters.
     
  2. Play "grind and chew" with the class. Have the class stand in a circle. An animal that eats plants has both vertical and lateral motion in the lower jaw. Make a motion with your jaws to illustrate the cow-like, sideways, grinding motion of a herbivore. Carnivores "bite" with an upward and downward (mainly vertical) motion, like a lion. Demonstrate the difference in this second type of motion to the class. Have students join you practicing carnivore and herbivore eating motions. Because humans eat both plants and meat, our jaw motion allows for both grinding and chewing.
     
  3. Hand out the worksheet and have students color dinosaurs with herbivore-like teeth green and those with carnivore-like teeth red. (Skulls 1 and 4 are carnivores; skulls 2 and 3 are herbivores.)
     
  4. Display the Carnegie dinosaur models and other dinosaur models. Ask the class to identify carnivores and herbivores. If you want to extend the lab, use the dinosaurs in the extinct animal models. The Dinosaur Placemats can also be used. The eating habits of the Carnegie Model dinosaurs are given below
Carnivore
Velociraptor
Tyrannosaurus
Herbivore
Apatosaurus
Stegosaurus
Brachiosaurus
Parasaurolophus
Triceratops
Euoplocephalus
Pachycephalosaurus
Maiasaura
Omnivore
Struthiomimus
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