Stegosaurus Plates and Tail Spikes: Armor of the Jurassic
Stegosaurus was 9 meters long and 5 tonnes, with 17 back plates and four 1-meter tail spikes.
Plates, size and tiny brain
Stegosaurus reached about 9 meters long and weighed near 5 tonnes, living in the Late Jurassic 155 to 150 million years ago. Seventeen bony plates ran along its arched back, likely used for display and temperature control.
Its brain was walnut-sized, weighing only about 80 grams for a 5-tonne animal. The small head carried weak beak-like jaws that cropped ferns and cycads, while huge hind legs powered slow walking.
Thagomizer tail weapon
The tail carried four sharp spikes each about 1 meter long, called the thagomizer. Strong muscles swung this weapon sideways, and fossil wounds prove it could pierce the bones of attacking theropods.
Plates were thin, blood-rich and staggered in two rows, reaching 60 centimeters tall. They could blush with blood to warn rivals, absorb morning heat, and make the animal look bigger to predators.
- Length 9 meters, weight 5 tonnes, Late Jurassic.
- 17 back plates for display and heat control.
- 4 tail spikes, each 1 meter long.
- Brain walnut-sized, only 80 grams.
- Tail could wound large theropod predators.