Stegosaurus stenops

Overview

Stegosaurus, meaning "roof lizard," is one of the most instantly recognizable dinosaurs thanks to its distinctive plates and spiked tail. This armored giant roamed North America during the Late Jurassic period, approximately 156 to 146 million years ago.

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Taxonomy & Classification

• Clade: Ornithischia (bird-hipped dinosaurs)
• Family: Stegosauridae
• Diet: Herbivorous
• Locomotion: Quadrupedal

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Physical Characteristics

Size & Build

• Length: 9 meters (30 feet)
• Height: Up to 4 meters (14 feet) at the plates
• Weight: 5,000-7,000 kg (5.5-7.7 tons)
• Brain Size: Famously tiny—about the size of a walnut!

The Famous Plates

• 17 bony plates arranged in two rows along its back
• Plates were not attached to the skeleton—they grew from the skin
• Largest plates could be 60 cm (2 feet) tall
• Probably used for temperature control and display, not armor

The Thagomizer

The tail spikes have a funny name with a serious purpose:

• Four sharp spikes, each up to 90 cm (3 feet) long
• Named "thagomizer" after a Far Side comic by Gary Larson
• Used as a deadly defensive weapon against predators like Allosaurus
• Fossil evidence shows these spikes caused real damage to attackers!

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Unique Anatomy

Body Design

• Front legs shorter than back legs, giving it a hunched posture
• Tiny head with a toothless beak and small leaf-shaped teeth
• Head positioned low, perfect for eating ground-level plants
• Powerful tail muscles could swing the thagomizer with tremendous force

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Diet & Feeding

Stegosaurus was a gentle plant-eater:

• Fed on ferns, cycads, and low-growing plants
• Could not raise its head very high
• Weak bite force but efficient at processing soft vegetation
• May have used its beak to strip leaves from plants

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Famous Fossils

"Apex" - The Million Dollar Dinosaur

• One of the most complete Stegosaurus skeletons ever found
• Sold at auction for a record $44.6 million in 2024
• Now on display at the American Museum of Natural History
• Standing 11 feet tall and 20 feet long!

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Defense & Survival

Despite its small brain, Stegosaurus was well-equipped to survive:

• The thagomizer could seriously injure or kill predators
• Plates may have made it look larger and more intimidating
• Likely lived in herds for added protection
• Predators like Allosaurus fossils show wounds matching Stegosaurus spikes!

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Cool Facts

• Stegosaurus had a brain the size of a lime but survived for millions of years!
• The word "thagomizer" is now used by actual scientists—thanks to a comic!
• It's the official state dinosaur of Colorado
• Despite the tiny brain, its nervous system had an enlargement near the hips that may have helped control the back legs and tail

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Stegosaurus proves you don't need a big brain to be a successful survivor—this plated wonder thrived for millions of years!