An Ultimate Guide to Stegosaurus: The Roof-Lizard

Leave a comment / / Updated on: 4th January 2024

Name MeaningRoof LizardHeightUp to 3.5 meters (11.4 feet)
Pronunciationstego-sore-usLength6.5 to 7.5 meters (21.3 to 24.6 feet)
EraMesozoicLate JurassicWeight3.5 to 5.3 metric tons (3.8 to 5.8 short tons)
ClassificationDinosauria,‭ ‬Ornithischia & ThyreophoraLocationWestern United States (USA), Portugal

Stegosaurus Pictures

Stegosaurus on top of the mountain
Stegosaurus on top of the mountain | FOTOKITA via GettyImages

The Stegosaurus

Gage Beasley Prehistoric's Stegosaurus Concept
Gage Beasley Prehistoric’s Stegosaurus Concept

Renowned for its distinctive broad plates and unique tail spikes, the Stegosaurus is probably at the top of the list of famous prehistoric creatures.

No wonder it’s one of the most iconic dinosaurs in the entertainment world!

Paleontological research estimates that Stegosaurus inhabited Earth during the Late Jurassic.

More precisely, from the Kimmeridgian age to the Tithonian age, around 155-145 million years ago.

Unlike many other dinosaur genera, Stegosaurus doesn’t consist of only one species.

Three recognized species need to be mentioned: Stegosaurus stenops, Stegosaurus ungulatus, and Stegosaurus sulcatus.

Gage Beasley's Prehistoric Shirt Collection
Gage Beasley’s Prehistoric Shirt Collection
Gage Beasley's Prehistoric Plush Collection
Gage Beasley’s Prehistoric Plush Collection

They were all herbivorous, quadrupedal dinosaurs that served as subjects for debate and research based on numerous discoveries that helped specialists shed light on the evolution and history of dinosaurs.

Not only did the Stegosaurus add a missing piece to the dinosaur family, but it also significantly contributed to describing the Late Jurassic and the prehistoric characteristics of the territories it once lived in: Portugal and the western United States.

As such, it shouldn’t be surprising that the genus was described in what we know as the Bone Wars or the Great Dinosaur Rush, a historically renowned fossil hunt competition!

What exactly did these dinosaurs look like? How did they eat and behave? Where did they live? And, most importantly, how were they discovered and described?

Keep reading, and you’ll learn some jaw-dropping details!

Physical Characteristics

Stegosaurus in Jurassic Park Movie
Stegosaurus in Jurassic Park Movie | Animalman57 via JurassicParkFandom

Needless to say, the Stegosaurus plates are their most recognizable characteristic.

These osteoderms were similar to those we see in crocodiles today.

Presumably, the Stegosaurus had a double row of plates along its back and two pairs of long spikes marking its tail.

There must’ve been around 17-22 plates, the largest measuring about 60 centimeters (23.6 inches), both tall and wide.

Moreover, one unique thing about these plates is that they weren’t attached to the skeleton as we might have thought. Instead, they grew from the skin.

It is thought that these plates helped scientists establish the three different species.

As for the plate arrangement, this gave birth to numerous debates and multiple cultural representations.

Stegosaurus ungulatus was the largest of the three.

Gage Beasley Prehistoric's Stegosaurus Size Comparison
Gage Beasley Prehistoric’s Stegosaurus Size Comparison

While Stegosaurus stenops measured roughly 6.5 meters (21.3 feet) long and weighed 3.5 metric tons (3.8 short tons), Stegosaurus ungulatus could reach 7-7.5 meters (23-24.6 feet) long and weigh up to 5.3 metric tons (5.8 short tons).

But enough about their length and weight! We’ve got something more interesting!

You’ve probably already heard that the Stegosaurus was often called the dumbest dinosaur. Why so? You’re wondering, right?

These creatures had relatively small skulls.

Imagine a 20-foot-long (6-meter) dinosaur with a skull the size of a dog’s! We can only imagine how small the brain was!

Othniel Charles Marsh, a professor of paleontology, confirmed that the dinosaur also had a very small brain, which couldn’t have weighed more than 80 grams (2.8 ounces)!

Is this indeed proof that the Stegosaurus wasn’t an intelligent creature? We saved the answer for later, so keep reading!

Here are some other characteristics that can help you distinguish the Stegosaurus from other dinosaurs if you see them on screen:

Stegosaurus | Syldavia via GettyImages
  • It had a rounded back.
  • The forelimbs were short, while the hindlimbs were longer and stocky.
  • The forelimbs had five toes, while the hind limbs had only three. All limbs had pads behind the toes.
  • It had a wide belly and an overall heavy build.
  • It usually kept its tail high in the air while the head was held close to the ground.
  • It had a short neck.

Habitat and Distribution

Stegosaurus fossils were recovered from two primary localities: the Lourinha Formation of Portugal and the Morrison Formation of the United States.

The Lourinha Formation is known to have hosted a fauna similar to the Morrison Formation, which is probably why the Stegosaurus settled in both.

In fact, some studies show that these two formations were home to two of the world’s richest terrestrial faunas in the Late Jurassic!

The Lourinha Formation is believed to have had a warm and wet climate with seasonal variations in precipitation.

The Morrison Formation is considered a semiarid to tropical wet-dry ecosystem divided into wet and dry seasons.

The two formations are thought to have a similar climate, except that the Lourinha was wetter, with around 766-1394 mm/year in the north and 877-1360 mm/year in the south.

Gage Beasley's Stegosaurus Dinosaur Soft Stuffed Plush Toy
Gage Beasley’s Stegosaurus Dinosaur Soft Stuffed Plush Toy

Moreover, another difference between the two is their position with regard to the ocean; the Morrison Formation extended throughout the center of the North American continent, having only some parts close to the water.

At the same time, the Lourinha Formation was much closer to the recently opened North Atlantic, thus having suffered major marine influence, which is why it was wetter than the Morrison Formation.

As such, it would be difficult to establish an exact habitat for the Stegosaurus, as it depends on where each specimen lived.

While the formations were somewhat similar in terms of paleoclimate, there were some major differences between the two that affected the fauna living there.

Behavior and Diet

Stegosaurus was a heavily armored herbivorous dinosaur that lived in North America during the Cretaceous Period
Stegosaurus was a heavily armored herbivorous dinosaur that lived in North America during the Cretaceous Period | CoreyFord via GettyImages

Although it was previously thought that the Stegosaurus was bipedal, this theory was soon abandoned, as the overall build of the dinosaur indicated that it was certainly quadrupedal.

The structure of the hind limbs suggests that the Stegosaurus was a slow-moving dinosaur, reaching maximum speeds of 15.3-17.9 km/h (9.5-11.1 mph).

It is highly likely that the Stegosaurus wasn’t capable of complex behavior because of its small brain, which is where the belief that it was not intelligent comes from.

However, scientists confirm that, while this might be true, it’s also true that the species didn’t actually need to develop complex behaviors.

After all, they weren’t predators requiring specialized hunting techniques to ensure survival!

Track discoveries show that the Stegosaurus might’ve lived and moved in herds of specimens of various ages.

While foraging, these dinosaurs most likely fed on low-growing plants.

While some scientists think they could stand up on their hind limbs to reach higher vegetation, this hasn’t been fully confirmed yet.

S. stenops skull cast, Natural History Museum of Utah
S. stenops skull cast, Natural History Museum of Utah | Daderot via Wikipedia (CC0)

As for their feeding strategy, this topic is still debated, as the Stegosaurus tooth and jaw structure wasn’t typical of herbivorous ornithischians.

More precisely, it had small, peg-shaped teeth and jaws capable only of up-and-down movements.

Therefore, compared to other ornithischians, the Stegosaurus couldn’t grind food.

Moreover, it’s also believed that it possessed no stones in its stomach that would help grind food.

As such, while paleontologists concluded that the Stegosaurus fed on ferns, mosses, conifers, and cycads, to name a few, they’re still unsure how exactly they processed these plants.

And, if this isn’t enough, the Stegosaurus is thought to have had a bite force less than half of the bite force of a Labrador, indicating that eating large plant parts was most probably out of the question.

Life Cycle

Stegosaurus walking with its child
Stegosaurus walking with its child | Chainarong Boonyindee via GettyImages

As with many other dinosaurs, little is known about their reproductive system.

It is known, however, that all dinosaurs had two oviducts and laid amniotic eggs, which is a significant starting point in describing the Stegosaurus’s reproductive process and life cycle.

It is believed that the copulation occurred while the female laid on her side since the plates must’ve been an obstacle in the process.

Some specialists suggest that the female stood on all four limbs and kept her posterior raised, supporting the male’s forelimbs with her hips.

However, this position was highly unlikely, as there’s little physiological evidence to confirm that the reproductive organs could connect this way.

Dinosaurs typically laid eggs in nests, although this hasn’t been confirmed for all species.

As such, there’s little scientific evidence to show the laying habits of the Stegosaurus.

Many dinosaurs are born either precocial or superprecocial, meaning they are born relatively mature, as odd as it may sound.

As such, we may suppose that a baby Stegosaurus was born precocial, too, but there’s no scientific evidence to confirm this.

On the other hand, some studies suggest that the growth rate of the Stegosaurus was slower than that of other dinosaurs, especially regarding the growth of their plates and spikes.

Another interesting thing about the Stegosaurus is that it might’ve exhibited sexual dimorphism.

More precisely, the females had three extra sacral ribs.

Evolution and History

3D render of a stegosaurus skeleton, isolated on white
3D render of a stegosaurus skeleton, isolated on white | LindaMarieB via GettyImages

The stegosaurian evolutionary history is linked to that of basal thyreophorans, as the bony plates and spines in these dinosaurs evolved from the latter’s low-keeled osteoderms.

The closest relatives to stegosaurians (Stegosauria) are the ankylosaurs (Ankylosauria), and the last common ancestor that unites the two is probably the Scelidosaurus, which lived around 196.5-183 million years ago.

Naturally, the Stegosaurus is by far the most studied genus in its Stegosauria suborder.

The first Stegosaurus fossils were some fragmented bones discovered by Arthur Lakes in the Bone Wars.

They were recovered from a locality called Lake’s YPM Saurian Quarry 5 in Morrison, Colorado, and later became the holotype for the 1877 description of Stegosaurus armatus.

However, the type specimen wasn’t complete enough for the named species to become the type species.

As such, the type species later became Stegosaurus stenops.

The evolution and history of these dinosaurs are also often linked to those of Hypsirhophus stegosaurians.

In fact, it was once believed they were the same dinosaurs, although some vertebrae differences later distinguished them.

The most significant discovery related to the genus, which revealed an almost complete subadult skeleton, occurred in 1885.

Naturally, this newly discovered dinosaur, with its unique appearance and the curious behavior it suggested, made paleontologists and other field-related specialists curious, thus leading to numerous other discoveries that continuously shaped the evolution of stegosaurians and thyreophorans in general.

Interactions With Other Species

Stegosaurus and Allosaurus
Stegosaurus and Allosaurus | MR1805 via GettyImages

The Stegosaurus must’ve shared its habitat with various theropods, including Allosaurus, Torvosaurus, Marshosaurus, and Ornitholestes.

Sauropods were common, too, especially Brachiosaurus, Diplodocus, and Apatosaurus. Other prehistoric creatures, like Camptosaurus or Dryosaurus, are thought to have lived on the same territory.

However, the species we’re discussing today is most often linked to Allosaurus, Camarasaurus, Diplodocus, and Apatosaurus.

While the Stegosaurus was a herbivore and didn’t seek confrontations with other dinosaurs, this doesn’t mean they weren’t at predation risk.

There’s evidence that it was attacked and possibly preyed upon by the ferocious Allosaurus.

Allosaurus and Stegosaurus
Allosaurus and Stegosaurus | Elenarts108 via GettyImages

Some studies indicate that the Stegosaurus was well-armored and could defend itself against predators thanks to its plates and spikes.

Other specialists think the opposite – the plates were too fragile and didn’t protect the dinosaur’s sides.

Another specialist suggested that the Stegosaurus could move its plates from side to side as a defense mechanism.

Others concluded that the plates served primarily for thermoregulation. All these hypotheses were questioned, and the subject is still up for debate.

The same goes for tail spikes; some specialists think they were only used for display, while others suggest they served as weapons.

What’s certain, though, is that paleontologists discovered an Allosaurus tail vertebra that had suffered a puncture where a Stegosaurus tail spike fitted perfectly.

Cultural Significance

Stegosaurus and King Kong in King Kong (1933) | Photo via Wikizilla

The influence the Stegosaurus had on popular culture is by far one of the most significant in the world of dinosaurs.

Having been depicted in numerous movies, cartoons, comics, and books, it’s no wonder they’re now one of the world’s most famous prehistoric creatures!

Here are some of the most known cultural depictions:

  • The earliest Stegosaurus image published in an 1884-issue of the popular American science magazine Scientific American;
  • A Stegosaurus sketch, which played a major role in the plot of the famous The Lost World written by Arthur Conan Doyle;
  • The Stegosaurus was the main hero of the famous children’s science fiction series Astrosaurs written by Steve Cole;
  • The Stegosaurus appeared in Michael Crichton’s Jurassic Park, as well, but was subsequently replaced by a Triceratops in the movie;
  • Its appearance in the 1933 King Kong movie;
  • The battle between a Stegosaurus and a Tyrannosaurus rex in the 1940 animated film called Fantasia;
  • Four characters in the Transformers universe can transform into the famous Stegosaurus;

These are only some of the earliest cultural depictions of the Stegosaurus.

They were followed by numerous other appearances that probably marked, more or less, every child’s perspective of this world’s prehistory.


One of the world’s most famous prehistoric creatures is the Stegosaurus!

Distinctive bony plates, tail spikes, and a unique quadrupedal body shape with a rounded back, short forelimbs, and long hind limbs are only some of the most curious things about this dinosaur!

Suppose we’re diving deep into what paleontologists discovered about the genus.

In that case, we soon realize that there’s so much yet to be understood about its behavior, defense mechanisms, and social and feeding strategies!

As such, while these stegosaurians probably contributed the most to outlining the evolution and history of dinosaurs overall, we can only hope that scientists will reveal new evidence about them!

Until then, we can enjoy their appearances on screen and in our favorite books!


Did T-Rex ever eat Stegosaurus?

Tyrannosaurus rex could not have preyed on Stegosaurus, as the two lived in different periods.

T-Rex roamed the Earth 68-66 million years ago, while Stegosaurus was a more ancient inhabitant, living around 155-145 million years ago.

Who is stronger: T-Rex or Stegosaurus?

T-Rex was an apex predator and probably stronger than Stegosaurus, a herbivore that likely didn’t develop any hunting techniques.

Let’s not forget that the Stegosaurus force bite was less than that of a Labrador!

Although they might’ve used its bony plates and tail spikes to defend itself, the T-Rex would’ve probably won in a fight anyway.


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