Lizard Hips and Bird Hips

Science · Dinosaurs & Paleontology · ages 9-11

Name ______________________ Date ____________

What part of a dinosaur's body decides if it is Saurischia or Ornithischia?
- Teeth
- Hip bones
- Neck length
What are the two big groups scientists sort dinosaurs into?
- Saurischia and Ornithischia
- Meat-eaters and plant-eaters
- Big dinosaurs and small dinosaurs
Ornithischia means "bird-hipped."
Circle one: True False
Triceratops has a backward-pointing hip bone like a bird's. Which group is Triceratops in?
- Ornithischia
- Saurischia
- Neither group
T. rex has lizard-shaped hip bones. Which group is T. rex in?
- Ornithischia
- Both groups
- Saurischia
Stegosaurus is bird-hipped and eats only plants. T. rex is lizard-hipped and eats meat. What can we say about their hip groups?
- They are in the same hip group because they each eat only one type of food
- They are in different hip groups
- They cannot be sorted into a hip group
A newly found dinosaur fossil has hip bones shaped like a bird's. Which group must it belong to?
- Ornithischia
- Saurischia
- It cannot be sorted without knowing its diet
Sam says Brachiosaurus must be Ornithischia because it eats only plants, just like Triceratops. What is wrong with his idea?
- Sam is right, every plant-eater is Ornithischia
- Brachiosaurus does not belong to any hip group
- Hip bone shape decides the group, not diet, and Brachiosaurus actually has lizard-shaped hips

Answer key

For grown-ups. Fold this page away before handing over the rest.

Hip bones · The shape of the hip bones puts a dinosaur into one group or the other.
Saurischia and Ornithischia · Saurischia and Ornithischia are the two hip groups. That sorting rule is different from the meat-eater versus plant-eater one you already learned.
True · That is right. Ornithischia dinosaurs have hip bones shaped like a bird's.
Ornithischia · A bird-shaped hip bone means Triceratops belongs to Ornithischia.
Saurischia · Lizard-hipped dinosaurs belong to Saurischia, and T. rex is a classic example.
They are in different hip groups · Hip bone shape sorts dinosaurs, and Stegosaurus and T. rex have different hip shapes, so they land in different groups.
Ornithischia · Hip bone shape is the only thing that matters for sorting. A bird-shaped hip always means Ornithischia.
Hip bone shape decides the group, not diet, and Brachiosaurus actually has lizard-shaped hips · Diet never decides the hip group. Brachiosaurus has lizard-shaped hips, so it is Saurischia even though it only eats plants.