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The big facts page

171 Stegosaurus facts, all checked

Every fact on this site in one place, each linked to its source. Our build checks each one against the source text; see the sources page. Figures that can change carry the date we checked them, and where sources disagree you’ll find both.

Jump to: The basics | Size (estimates vary) | The plates and spikes | What were the plates for? (open question) | The tail | Head, brain, body and skin | Food and life | Sophie, the Natural History Museum’s Stegosaurus | The Smithsonian’s Stegosaurus | Apex | Discovery, names and myths | Its world | The plated and armoured relatives

The basics

  1. 1 Stegosaurus means “roof lizard”. Natural History Museum: Stegosaurus (Dino Directory)
  2. 2 You say it STEG-oh-SORE-us. Natural History Museum: Stegosaurus (Dino Directory)
  3. 3 Stegosaurus was named by Othniel Charles Marsh in 1877. Natural History Museum: Stegosaurus (Dino Directory)
  4. 4 The Natural History Museum dates it to the Late Jurassic, 152 to 145 million years ago. Natural History Museum: Stegosaurus (Dino Directory) · checked 27 Oct 2026
  5. 5 In the Natural History Museum’s directory, its fossils come from the USA. Natural History Museum: Stegosaurus (Dino Directory)
  6. 6 Stegosaurus was a large, slow-moving plant eater. Natural History Museum: Stegosaurus (Dino Directory)
  7. 7 It was an armoured dinosaur, part of the group called stegosaurs. Natural History Museum: Stegosaurus (Dino Directory)
  8. 8 Stegosaurs had two rows of tall bony plates and/or spines running from the neck to the end of the tail. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  9. 9 Despite being so famous, well-preserved Stegosaurus fossils are surprisingly rare: most specimens are less than half a skeleton. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  10. 10 Stegosaurus lived about 150 million years ago and T. rex about 70 million years ago, so we live closer in time to T. rex than Stegosaurus did. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus”
  11. 11 Stegosaurus was extinct long before the dinosaurs’ mass extinction 66 million years ago. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus”

Size (estimates vary)

  1. 12 The Natural History Museum gives its length as 9 metres. Natural History Museum: Stegosaurus (Dino Directory) · checked 27 Oct 2026
  2. 13 Other Stegosaurus specimens reach up to nine metres long, the Museum says. Natural History Museum: Stegosaurus Q&A with Prof Paul Barrett · checked 27 Oct 2026
  3. 14 Sophie, the Natural History Museum’s Stegosaurus, is 560 cm long and 290 cm tall, about the size of a 4x4 car. Natural History Museum press release: World’s most complete Stegosaurus goes on show, 2014
  4. 15 Sophie weighed about 1,600 kg in life, roughly the weight of a small rhino. Natural History Museum: Secrets of the Stegosaurus, 2014 · checked 27 Oct 2026
  5. 16 The exact estimate was 1,560 kg, with a likely range of 1,082 to 2,256 kg. Brassey, Maidment & Barrett (2015), Body mass estimates of an exceptionally complete Stegosaurus, Biology Letters · checked 27 Oct 2026
  6. 17 Equations based on leg bones gave 2,355 to 3,751 kg, far more, until the team allowed for Sophie not being fully grown. Brassey, Maidment & Barrett (2015), Body mass estimates of an exceptionally complete Stegosaurus, Biology Letters
  7. 18 An American Museum of Natural History curator describes an adult’s body as about five tons. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus” · checked 27 Oct 2026
  8. 19 The Smithsonian calls its body “schoolbus-sized”. Smithsonian Magazine: Meet the dinos of “Deep Time”, 2019 · checked 27 Oct 2026
  9. 20 Apex, a big old Stegosaurus, is 11.5 feet (3.5 m) tall and 27 feet (8.2 m) long, about 30 percent larger than others. Smithsonian Magazine: Apex on display in New York, 2024 · checked 27 Oct 2026
  10. 21 When it was sold, Apex was reported as 11 feet (3.4 m) tall and 20 feet (6.1 m) long, and more than 30 percent larger than Sophie. Smithsonian Magazine: “Apex” sells for $44.6 million, 2024 · checked 27 Oct 2026
  11. 22 The same article says Stegosaurus could weigh almost 14,000 pounds (about 6.4 tonnes) and grow 21 to 30 feet (6.4 to 9.1 m) long. Smithsonian Magazine: “Apex” sells for $44.6 million, 2024 · checked 27 Oct 2026

The plates and spikes

  1. 23 The plates were embedded in the skin, not attached to the skeleton, which is why they are usually found separated from the body. Natural History Museum: Stegosaurus (Dino Directory)
  2. 24 The plates stood upright, alternating on either side of the spine. Natural History Museum: Stegosaurus (Dino Directory)
  3. 25 Sophie has 19 plates and four tail spikes, the most complete set ever discovered. Natural History Museum press release: World’s most complete Stegosaurus goes on show, 2014
  4. 26 One of Sophie’s 19 plates is a cast. Natural History Museum: Secrets of the Stegosaurus, 2014
  5. 27 Eighteen plates and four spikes were found in place. A gap above the tail suggests one more plate washed away, so the full set was probably 19 plates and four spikes. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  6. 28 Before Sophie, the 1914 study of Stegosaurus guessed there were probably 20 plates. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  7. 29 Even with Sophie, scientists can’t tell which way each plate leaned, left or right. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  8. 30 Sophie’s biggest plate is number 13, about 785 mm tall, though part of it is plaster. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  9. 31 Her four front plates, on the neck, are almost identical in shape and only about 10 to 13 cm tall. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  10. 32 Sophie’s tail spikes are 34 to 38 cm long. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  11. 33 In life the plates were probably covered in keratin, the material of fingernails. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus”
  12. 34 The Smithsonian also describes the plates as keratin-covered. Smithsonian Magazine: Stegosaurus plate debate, 2012
  13. 35 Tiny grooves on the plates may mark where blood vessels ran. Natural History Museum: Stegosaurus (Dino Directory)
  14. 36 Many other stegosaurs had long rows of spikes and short plates. Stegosaurus had huge alternating plates and just four tail spikes. Smithsonian Magazine: Stegosaurus plate debate, 2012
  15. 37 Unlike some relatives, Stegosaurus had no big shoulder spikes. Smithsonian Magazine: Tracking cryptic stegosaurs, 2010
  16. 38 An AMNH curator points out the plates were only loosely attached, so may not have stood up to a predator’s bite. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus”
  17. 39 Some Stegosaurus specimens have small pebble-like bones in the throat. Sophie doesn’t, and nobody yet knows why. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  18. 40 The Smithsonian’s Stegosaurus has bony nodules guarding its neck. Smithsonian Magazine: Meet the dinos of “Deep Time”, 2019

What were the plates for? (open question)

  1. 41 Scientists are not exactly sure what the plates were for. Ideas include warning off predators, recognising their own kind, and controlling body temperature. Natural History Museum: Stegosaurus (Dino Directory)
  2. 42 Defence is now out of fashion, because the plates, though large, are thin and fragile. Natural History Museum: A Stegosaurus brought to life
  3. 43 The Natural History Museum now favours one of two jobs: display, or controlling temperature. Natural History Museum: A Stegosaurus brought to life
  4. 44 The plates seem to have been full of blood vessels, which could have carried warm blood up to shed heat. Natural History Museum: A Stegosaurus brought to life
  5. 45 Wind-tunnel tests in 1976 showed the plates could shed heat, but a 2010 follow-up found no sign they evolved for that. Smithsonian Magazine: Stegosaurus plate debate, 2012
  6. 46 A 2005 study of plate microstructure found no evidence they were used to radiate heat. Smithsonian Magazine: Stegosaurus plate debate, 2012
  7. 47 Stegosaur plates and spikes varied greatly between species, which suggests display drove their evolution. Smithsonian Magazine: Stegosaurus plate debate, 2012
  8. 48 An AMNH curator says display, to mates or rivals, is the most likely function. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus”
  9. 49 A Smithsonian curator says the plates’ purpose “remains a bit of a mystery”. Smithsonian Magazine: Meet the dinos of “Deep Time”, 2019
  10. 50 Smithsonian Magazine wrote in 2024 that the plates’ function remains an enigma. Smithsonian Magazine: Apex on display in New York, 2024 · checked 27 Oct 2026

The tail

  1. 51 Stegosaurus would have defended itself from predators like Allosaurus and Ceratosaurus with its spiked tail. Natural History Museum: Stegosaurus (Dino Directory)
  2. 52 The spiky tail is nicknamed the “thagomizer”, after a Far Side cartoon by Gary Larson about “the late Thag Simmons”. Smithsonian Magazine: Watch out for that thagomizer!, 2011
  3. 53 “Thagomizer” isn’t an official science term: palaeontologists also just say tail spikes. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus”
  4. 54 Humans and Stegosaurus missed each other by over 140 million years. Smithsonian Magazine: Watch out for that thagomizer!, 2011
  5. 55 An Allosaurus tail bone from Utah’s Cleveland-Lloyd Quarry has a hole about 1.5 inches square that a Stegosaurus spike fits. The bone had started to heal. Smithsonian Magazine: Watch out for that thagomizer!, 2011
  6. 56 Of 51 Stegosaurus spikes studied, about one in ten had broken tips that had healed, a sign they were used in fights. Smithsonian Magazine: Watch out for that thagomizer!, 2011
  7. 57 A neck plate from the same quarry has a U-shaped notch that matches the front of an Allosaurus’s jaws. Smithsonian Magazine: Watch out for that thagomizer!, 2011
  8. 58 Models suggest a spike driven in at an angle could get stuck and break, injuring both animals. Smithsonian Magazine: Watch out for that thagomizer!, 2011
  9. 59 Researchers have found Stegosaurus fossils with Allosaurus bite marks. Natural History Museum: Allosaurus (Dino Directory)
  10. 60 The Natural History Museum lists Stegosaurus as food for Allosaurus. Natural History Museum: Allosaurus (Dino Directory)
  11. 61 An AMNH curator says the tail spikes were probably for defence, not attack. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus”
  12. 62 In the Smithsonian’s Deep Time hall, a Stegosaurus swings its spiky tail at a Ceratosaurus. Smithsonian fact sheet: David H. Koch Hall of Fossils – Deep Time

Head, brain, body and skin

  1. 63 Its head was small, and its brain was around the size of a plum, says the Natural History Museum. Natural History Museum: Stegosaurus (Dino Directory)
  2. 64 An AMNH curator compares the brain to a small lemon or lime. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus”
  3. 65 The Smithsonian says it has been described as the size and shape of a bent hot dog. Smithsonian Magazine: Meet the dinos of “Deep Time”, 2019
  4. 66 It had one of the smallest brain-to-body size ratios of any dinosaur. Smithsonian Magazine: Meet the dinos of “Deep Time”, 2019
  5. 67 For its small skull, though, the brain was not exceptionally small compared with other reptiles. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus”
  6. 68 Its teeth were the size of a little fingernail. Natural History Museum: A Stegosaurus brought to life
  7. 69 It had a beak at the front of its jaws and teeth at the back, a bit like a green iguana’s. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus”
  8. 70 Its front legs were short and back legs long, because its ancestors walked on two legs. Natural History Museum: A Stegosaurus brought to life
  9. 71 It couldn’t run: it probably walked at the speed of a walking rhino or elephant, only a few miles an hour. Natural History Museum: A Stegosaurus brought to life
  10. 72 Big hip muscles and wide hips mean Sophie probably had “quite a large rear end”. Natural History Museum news: Weight of the world’s most complete Stegosaurus revealed, 2015
  11. 73 Its backbones are especially tall, making the back stiff, and nobody is sure why. Its short front legs are a puzzle too. Smithsonian Magazine: Meet the dinos of “Deep Time”, 2019
  12. 74 Its skin probably looked scaly, like a crocodile’s or lizard’s. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus”
  13. 75 Stegosaurus didn’t have feathers, but a few fibres on its body can’t be ruled out. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus”
  14. 76 There is no direct evidence of what colour Stegosaurus was. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus”
  15. 77 No Stegosaurus eggs have ever been found. The smallest juveniles known are about a metre long. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus”
  16. 78 Nobody knows how long a Stegosaurus lived. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus”

Food and life

  1. 79 It probably ate ferns, cycads and other tough vegetation. Natural History Museum: A Stegosaurus brought to life
  2. 80 CT scans of Sophie’s skull showed a bite force similar to a cow’s or a sheep’s, and efficient jaws. Natural History Museum: A Stegosaurus brought to life
  3. 81 A 2016 study estimated its bite at 231 to 410 newtons, higher than two other plant-eating dinosaurs it tested. Lautenschlager, Brassey, Button & Barrett (2016), Decoupled form and function in disparate herbivorous dinosaurs, Scientific Reports · checked 27 Oct 2026
  4. 82 An earlier 2010 computer model suggested a weak bite, able to cut twigs under half an inch thick. Smithsonian Magazine: The weak bite of Stegosaurus, 2010 · checked 27 Oct 2026
  5. 83 With its short neck, it probably fed on plants low to the ground. Smithsonian Magazine: Meet the dinos of “Deep Time”, 2019
  6. 84 Its world had cycads, ferns and horsetails, with a few conifers, and no flowering plants or grasses. Natural History Museum: Stegosaurus Q&A with Prof Paul Barrett
  7. 85 Sophie lived about 150 million years ago in a fairly harsh, arid environment. Natural History Museum: Stegosaurus Q&A with Prof Paul Barrett
  8. 86 The Natural History Museum says Stegosaurus didn’t live in herds: probably alone or in small groups. Natural History Museum: Stegosaurus Q&A with Prof Paul Barrett
  9. 87 Stegosaurus wasn’t common: on a Jurassic safari it would have been an interesting spot. Natural History Museum: Stegosaurus Q&A with Prof Paul Barrett
  10. 88 An AMNH curator says stegosaur fossils are often single animals, sometimes found with big sauropods, and stegosaur-only herds may have been rare. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus”
  11. 89 A 2015 study described a Montana quarry where at least five plated stegosaurs were buried together, which possibly suggests they were social. Saitta (2015), Evidence for sexual dimorphism in the plated dinosaur Stegosaurus mjosi, PLOS ONE
  12. 90 That study found two plate shapes, wide oval plates and tall narrow ones, and proposed they were males and females. Saitta (2015), Evidence for sexual dimorphism in the plated dinosaur Stegosaurus mjosi, PLOS ONE
  13. 91 A study of Sophie the same year said there are, as yet, no reliable ways to tell male from female Stegosaurus. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  14. 92 It is difficult to tell male and female dinosaurs apart: to prove a female you need eggs inside, or a special egg-laying bone tissue. Natural History Museum: Stegosaurus Q&A with Prof Paul Barrett

Sophie, the Natural History Museum’s Stegosaurus

  1. 93 Sophie is about 150 million years old and the only Stegosaurus in a public collection outside the USA. Natural History Museum press release: World’s most complete Stegosaurus goes on show, 2014 · checked 27 Oct 2026
  2. 94 Sophie went on show at the Natural History Museum in London on 4 December 2014. Natural History Museum press release: World’s most complete Stegosaurus goes on show, 2014
  3. 95 The skeleton has over 300 bones, with only the left arm and base of the tail missing. Natural History Museum press release: World’s most complete Stegosaurus goes on show, 2014
  4. 96 The Museum’s 3D model has 360 bones. Natural History Museum news: Weight of the world’s most complete Stegosaurus revealed, 2015
  5. 97 Bob Simon found it in spring 2003 at Red Canyon Ranch in Wyoming. It took three weeks to dig out. Natural History Museum press release: World’s most complete Stegosaurus goes on show, 2014
  6. 98 He spotted it after accidentally grazing a hillside with a bulldozer during a severe windstorm. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  7. 99 It was so well preserved because it was buried quickly in a pond or other standing water just after death. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  8. 100 It is named after Sophie Herrmann, daughter of Jeremy Herrmann, who helped 70 donors buy it. Natural History Museum press release: World’s most complete Stegosaurus goes on show, 2014
  9. 101 Sophie’s sex is unknown: the name doesn’t mean it was female. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  10. 102 Sophie was a young adult, still growing, when it died. Natural History Museum press release: World’s most complete Stegosaurus goes on show, 2014
  11. 103 Some gaps between bones were still open, and at just over 5.5 m it still had a way to grow. Natural History Museum: Stegosaurus Q&A with Prof Paul Barrett
  12. 104 One toenail looks trodden on and infected, but probably wasn’t fatal. Nobody knows why Sophie died. Natural History Museum: Stegosaurus Q&A with Prof Paul Barrett
  13. 105 Museum scientists spotted a cast of it at the Tucson Gem and Mineral Fair in 2012. Natural History Museum: Stegosaurus Q&A with Prof Paul Barrett
  14. 106 Its skull bones are three-dimensional and separate, one of the most scientifically valuable dinosaur skulls ever found. Natural History Museum press release: World’s most complete Stegosaurus goes on show, 2014
  15. 107 Before Sophie, the last detailed study of Stegosaurus was in 1914. Natural History Museum: Stegosaurus Q&A with Prof Paul Barrett
  16. 108 Only about a fifth of known dinosaur species are known from essentially complete skeletons. Natural History Museum: Stegosaurus Q&A with Prof Paul Barrett
  17. 109 Sophie belongs to the species Stegosaurus stenops. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  18. 110 The Natural History Museum calls Sophie the world’s most complete Stegosaurus. Natural History Museum press release: World’s most complete Stegosaurus goes on show, 2014

The Smithsonian’s Stegosaurus

  1. 111 The Smithsonian’s Stegosaurus stenops is the type specimen of its species: the first of its kind to be found and named. Smithsonian Magazine: Meet the dinos of “Deep Time”, 2019
  2. 112 Before it was dug up in 1886, scientists had only bits and pieces of Stegosaurus skeletons. Smithsonian Magazine: Meet the dinos of “Deep Time”, 2019
  3. 113 It is displayed in the death pose it was found in, in Colorado. Smithsonian Magazine: Meet the dinos of “Deep Time”, 2019
  4. 114 Older complete specimens like this one are ‘road kill’ fossils: many bones are crushed flat. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  5. 115 The Smithsonian’s Deep Time hall shows a composite cast of Stegosaurus stenops facing a Ceratosaurus. Smithsonian NMNH virtual tour: Stegosaurus spikes vs. Ceratosaurus claws
  6. 116 The Smithsonian’s label dates that Stegosaurus to 157 to 153 million years ago. Smithsonian NMNH virtual tour: Stegosaurus spikes vs. Ceratosaurus claws · checked 27 Oct 2026
  7. 117 The Smithsonian’s Deep Time article gives 157 to 148 million years ago for Stegosaurus. Smithsonian Magazine: Meet the dinos of “Deep Time”, 2019 · checked 27 Oct 2026

Apex

  1. 118 In 2024 a Stegosaurus called Apex sold at auction for a record $44.6 million, the most expensive fossil ever auctioned. Smithsonian Magazine: “Apex” sells for $44.6 million, 2024
  2. 119 Apex was discovered in May 2022 in the Morrison Formation in northwest Colorado. Smithsonian Magazine: “Apex” sells for $44.6 million, 2024
  3. 120 Apex has 254 of about 320 bones, roughly 80 percent of the skeleton. Smithsonian Magazine: Apex on display in New York, 2024 · checked 27 Oct 2026
  4. 121 Apex went on display at the American Museum of Natural History in New York on 8 December 2024, on loan for four years. Smithsonian Magazine: Apex on display in New York, 2024 · checked 27 Oct 2026
  5. 122 Apex lived into old age, and the museum is studying a thigh-bone sample to learn how stegosaurs grew. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus” · checked 27 Oct 2026
  6. 123 Apex’s shoulder blade has a puncture wound with a bit of its own tail bone inside. It may have stabbed itself. Smithsonian Magazine: Apex on display in New York, 2024
  7. 124 Many scientists worry when important fossils go to private buyers, because they may not stay available for research. Smithsonian Magazine: “Apex” sells for $44.6 million, 2024

Discovery, names and myths

  1. 125 When Marsh described Stegosaurus in 1877 he thought it looked like a giant turtle, with the plates forming a bony “roof”, hence the name. Smithsonian Magazine: The myth of the eight-spiked Stegosaurus, 2011
  2. 126 Marsh first thought the plates lay flat. A mud-covered specimen later showed they stood upright. Natural History Museum: Stegosaurus (Dino Directory)
  3. 127 In 1880 Marsh suggested the spikes were on its wrists. Smithsonian Magazine: The myth of the eight-spiked Stegosaurus, 2011
  4. 128 A quarry sketch from collector William Reed showed spikes at the tail tip. Marsh changed his mind by 1887. Smithsonian Magazine: The myth of the eight-spiked Stegosaurus, 2011
  5. 129 Marsh’s 1891 skeleton drawing had eight tail spikes, a mash-up of several specimens. There is no evidence for any number other than four. Smithsonian Magazine: The myth of the eight-spiked Stegosaurus, 2011
  6. 130 Marsh described a space in its hips as “a posterior braincase” in 1881, the start of the second-brain myth. Smithsonian Magazine: The double dinosaur brain myth, 2012
  7. 131 No dinosaur had a second brain. Smithsonian Magazine: The double dinosaur brain myth, 2012
  8. 132 The leading idea is that the hip space held a glycogen body, like birds have, though what it does is still unclear. Smithsonian Magazine: The double dinosaur brain myth, 2012
  9. 133 The Natural History Museum says the hip space was a store of food substances to help survive lean times. Natural History Museum: A Stegosaurus brought to life
  10. 134 An AMNH curator calls it an enlarged space for the nerve cord, not a brain. American Museum of Natural History: Apex Stegosaurus fossil and “11 Questions About Stegosaurus”
  11. 135 Marsh’s first species, Stegosaurus armatus (1877), was based on scrappy fossils. Smithsonian Magazine: Playing the stegosaur name game, 2010
  12. 136 In 2013 the official naming commission made Stegosaurus stenops the type species, replacing S. armatus. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  13. 137 The Natural History Museum’s directory still lists the type species as armatus. Natural History Museum: Stegosaurus (Dino Directory) · checked 27 Oct 2026
  14. 138 Some scientists count Hesperosaurus as a species of Stegosaurus (Stegosaurus mjosi). Others, including one of the scientists who named it, say it is a separate genus. Smithsonian Magazine: Playing the stegosaur name game, 2010
  15. 139 The 2015 study of Sophie lists Hesperosaurus and Wuerhosaurus as the same genus as Stegosaurus. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  16. 140 That study also treats Stegosaurus ungulatus as the same species as S. stenops. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  17. 141 Whether two fossils are separate species is decided by scientists comparing bones, and they don’t always agree. Smithsonian Magazine: Playing the stegosaur name game, 2010
  18. 142 The Natural History Museum calls Dacentrurus the first stegosaur ever discovered. Natural History Museum: Dacentrurus (Dino Directory)
  19. 143 The Smithsonian says the first trace of a stegosaur was found in South Africa in 1845 and is now called Paranthodon. Smithsonian Magazine: Tracking cryptic stegosaurs, 2010
  20. 144 Dacentrurus was first named Omosaurus armatus, and its plates were once mistaken for the head plates of a giant fish. Smithsonian Magazine: Tracking cryptic stegosaurs, 2010
  21. 145 Stegosaurus became Colorado’s state fossil on 28 April 1982, after a fourth-grade class campaigned for two years. Colorado State Archives: Symbols & Emblems
  22. 146 Old museum reconstructions show some changing ideas: Kentrosaurus in Berlin was first mounted with sprawling legs and a dragging tail. Smithsonian Magazine: The many postures of Kentrosaurus, 2010

Its world

  1. 147 Stegosaurus fossils come from the Morrison Formation, which also holds Allosaurus, Brontosaurus and Diplodocus. Natural History Museum: Diplodocus (Dino Directory)
  2. 148 Sophie comes from the Morrison Formation near Shell, Wyoming. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  3. 149 It shared the land with Diplodocus, Camarasaurus, Camptosaurus, Allosaurus and Ceratosaurus. Natural History Museum: Stegosaurus Q&A with Prof Paul Barrett
  4. 150 Apatosaurus lived alongside Stegosaurus, Diplodocus and Allosaurus, in a semi-arid land with forests, rivers and wet and dry seasons. Natural History Museum: Apatosaurus (Dino Directory)
  5. 151 Its predators included Allosaurus, Torvosaurus and Ceratosaurus. Smithsonian Magazine: Stegosaurus plate debate, 2012
  6. 152 Stegosaurs lived from the Middle Jurassic to the Early Cretaceous, and have been found on every continent except Australia and Antarctica. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  7. 153 Stegosaurus itself has also been reported from Portugal. Maidment, Brassey & Barrett (2015), The postcranial skeleton of an exceptionally complete individual of Stegosaurus stenops, PLOS ONE
  8. 154 Allosaurus: “different lizard”, 9.7 m long, a meat eater with horns above its eyes. Natural History Museum: Allosaurus (Dino Directory)
  9. 155 Ceratosaurus: “horned lizard”, 7 m long, with a horn on its snout and small bony armour along its back. Natural History Museum: Ceratosaurus (Dino Directory)
  10. 156 Diplodocus: “double beam”, 26 m long, with a long neck and whip-like tail. Natural History Museum: Diplodocus (Dino Directory)
  11. 157 Brachiosaurus: “arm lizard”, 22 m long, with front legs longer than its back legs. Natural History Museum: Brachiosaurus (Dino Directory)
  12. 158 Camarasaurus: “chambered lizard”, 23 m long, which stripped leaves with rows of teeth. Natural History Museum: Camarasaurus (Dino Directory)
  13. 159 Camptosaurus: “bent lizard”, a 5 m plant eater that walked on two or four legs. Natural History Museum: Camptosaurus (Dino Directory)

The plated and armoured relatives

  1. 160 Kentrosaurus: “spiky lizard”, 5 m long, from Tanzania, 155 to 150 million years ago. Natural History Museum: Kentrosaurus (Dino Directory)
  2. 161 Kentrosaurus was named by Hennig in 1915. Natural History Museum: Kentrosaurus (Dino Directory)
  3. 162 A 2010 computer study found Kentrosaurus could sprawl its front legs to brace itself while swinging its tail. Smithsonian Magazine: The many postures of Kentrosaurus, 2010
  4. 163 Tuojiangosaurus: “Tuo River lizard”, 7 m long and 1,500 kg, from China, 157 to 154 million years ago. Natural History Museum: Tuojiangosaurus (Dino Directory)
  5. 164 Huayangosaurus: “Huayang lizard”, 4.5 m long, from China, 170 to 160 million years ago in the Middle Jurassic. Natural History Museum: Huayangosaurus (Dino Directory)
  6. 165 Dacentrurus: “pointed tail”, 6 m long, from England, France and Portugal, 154 to 150 million years ago. Natural History Museum: Dacentrurus (Dino Directory)
  7. 166 Scelidosaurus: “limb lizard”, a 4 m armoured dinosaur from England, 208 to 194 million years ago in the Early Jurassic. Natural History Museum: Scelidosaurus (Dino Directory)
  8. 167 Gargoyleosaurus: “gargoyle lizard”, a 4 m armoured dinosaur from the USA, 154 to 142 million years ago. Natural History Museum: Gargoyleosaurus (Dino Directory)
  9. 168 Ankylosaurus: “fused lizard”, 8 m long, with a heavy tail club, 68 to 66 million years ago. Natural History Museum: Ankylosaurus (Dino Directory)
  10. 169 Miragaia, a long-necked stegosaur from Portugal, is the most complete stegosaur described from Europe. Costa & Mateus (2019), Dacentrurine stegosaurs: a new specimen of Miragaia longicollum, PLOS ONE
  11. 170 In 2024 scientists named Baiyinosaurus, a Middle Jurassic stegosaur from Gansu, China, which helps show how stegosaurs began. Li Ning et al. (2024), A new stegosaur from the Middle Jurassic of Gansu Province, China, Scientific Reports · checked 27 Oct 2026
  12. 171 Because of a poor fossil record, the early evolution of stegosaurs is poorly understood. Li Ning et al. (2024), A new stegosaur from the Middle Jurassic of Gansu Province, China, Scientific Reports