Dinosaurs

What is a dinosaur?• Dinosauria

– Stands upright (erect, not sprawling)– Ball-and-socket hip joint– Straight knee joint– Straight ankle joint– Ankle bones closely attached to the shin

bone

A B

Erect stance of mammals and dinosaurs

Sprawling posture of most reptiles

Where did dinosaurs come from?• The first dinosaurs

were small bipeds• They ate insects and

small vertebrates• Then, after 5 million

years they had their chance!

• They radiated after a mass extinction 225 myr ago

“Archosauria”

The First Dinosaurs

• Eoraptor

• Herrerasaurus

Both are from the Ischigualasto Formation in Patagonia, Argentina

cc. Arthur Weasley

• Origin of the Earth: 4600 Myr• Origin of life: 3500 Myr• First fishes: 545 Myr• First tetrapods: 380 Myr• First reptiles: 320 Myr• First archosaurs: 250 Myr• First dinosaurs: 230 Myr

When did this happen?

cc. Arthur Weasley

Mesozoic Era• Mesozoic: “The Age of the Dinosaurs”

• The world of the dinosaurs was very different from the world today

The supercontinent Pangea

cc. Gerhard Boeggemann