Gioca STEMAnimals

Animals · Giants of the past

Stegosaurus

Stegosaurus stenops

Two rows of plates along the back

Back plates arranged in two alternating rows, the main reconstruction used from the nineteen sixties until today.
Back plates arranged in two alternating rows, the main reconstruction used from the nineteen sixties until today.
  • Status: Extinct
  • Fossils in the western United States and Portugal
  • Extinct

Photos and pictures

6 pictures: tap to see them large.

  • Photo: Gary Todd from Xinzheng, China · CC0Wikimedia Commons · original · license
  • Photo: 先従隗始 · CC0Wikimedia Commons · original · license
  • Photo: Gary Todd from Xinzheng, China · CC0Wikimedia Commons · original · license

  • Reconstruction: a drawing of how it looked when alive

  • Reconstruction: a drawing of how it looked when alive

  • Reconstruction: a drawing of how it looked when alive

Numbers

Weight
8 ton (7.3 t)estimate; others start from 5 tons
Length
30 ft (9.1 m)up to 38 feet in an old specimen of S. ungulatus
Height
10 ft (3 m)adult estimate; a juvenile measured 6.5 ft
Lifespan
155 million years agoLate Jurassic, between Kimmeridgian and Tithonian: 155 to 145 million years ago
Back plates
24 in (61 cm)the largest, on the sides, two feet wide and tall
Tail spikes
3 ft (91 cm)four spikes, the structure called a thagomizer
Brain weight
3 oz (85 g)in an animal of over 5 tons

Ten fun facts

  1. The name of its tail spikes, the thagomizer, comes from a comic strip by Gary Larson and entered official scientific texts.

  2. The scientist Marsh first thought he found a giant sea turtle, which led to the name meaning roof lizard.

  3. The plates were not attached to the skeleton, but only to the skin, just like the skin bones of crocodiles.

  4. No two plates on the same individual were identical in shape or size, not even those right next to each other.

  5. A teenage specimen found in Wyoming in 1994 measured fifteen feet long and weighed about two and a half tons.

  6. The brain cavity cast created by Marsh in 1880 remains the smallest known brain cast among all dinosaurs.

  7. A study revealed clear damage on the tail spikes of nearly ten percent of all examined specimens.

  8. An Allosaurus backbone fossil was found with a hole that fits a Stegosaurus tail spike perfectly.

  9. The front feet had five toes while the back feet had only three stubby toes supported by thick pads.

  10. Many museum skeletons are assembled from the bones of several individuals because complete skeletons were rare.

The quiz answers

Five questions about this animal. Pick an answer and find out if it is the right one.

Question 1 of 5

How many spikes did it have at the end of its tail?

Question 2 of 5

How were the back plates attached?

Question 3 of 5

What did it have instead of front teeth?

Question 4 of 5

How much did its brain weigh?

Question 5 of 5

In which period did it live?

Try it yourself

Experiment 1

Cut a diamond shape measuring two feet by two feet out of cardboard to match the largest plates. Stand it up to see how huge it is.

Experiment 2

Weigh three ounces of flour on a kitchen scale to see the brain size of an animal that weighed over five tons.

Experiment 3

Unroll a measuring tape on the floor up to three feet. That was the length of just one of the four spikes on its tail.

Data from Wikidata (Q14388) and Wikipedia (Stegosaurus).