Stegosaurus
In 1877, Othniel Charles Marsh described the first Stegosaurus fossils found by Arthur Lakes near Morrison, Colorado. The initial bones were fragmentary and scattered across what became known as YPM Quarry 5. Marsh initially misinterpreted these remains as belonging to an aquatic turtle-like creature due to the presence of a single dermal plate. He named the species Stegosaurus armatus, meaning armored roof lizard, believing the plates lay flat like shingles on a roof rather than standing upright. This early error persisted for years until more complete specimens emerged from the field. The type specimen consisted only of partial tail vertebrae, hips, leg fragments, and one small plate. No other plates or spikes were preserved with this original find, making it extremely difficult to compare with later discoveries. Marsh also incorrectly assigned sauropod limb bones and an Allosaurus tibia to this same collection. These errors would haunt the genus name for decades before paleontologists could correct the record.
The Peabody Museum of Natural History mounted its first Stegosaurus skeleton in 1910 under Richard Swann Lull's direction. This display featured paired plates set wide above the base of ribs based on early interpretations. By 1924, the museum remounted the exhibit with two staggered rows of plates along the midline after new evidence emerged. Charles Gilmore argued against the earlier paired arrangement at the U.S. National Museum of Natural History in 1914. He noted that several S. stenops fossils preserved plates in alternating rows near the peak of the back without any shifting during fossilization. The American Museum of Natural History opened their composite mount in 1932 under Charles J. Long. Barnum Brown disputed the popular misconception about a second brain while describing this new installation. In 1940, the Carnegie Museum displayed another composite using specimens collected from Dinosaur National Monument between 1920 and 1922. Many museums had to assemble these displays from multiple different specimens due to the lack of complete skeletons available at the time.
Peter Galton published a 2010 review suggesting plate arrangements might vary between species for identification purposes. Most S. stenops specimens show plates arranged in two staggered rows rather than pairs. Hesperosaurus skin impressions reveal smooth surfaces covered by keratinous sheaths with parallel shallow grooves. Christiansen and Tschopp studied well-preserved Hesperosaurus specimens concluding the plates likely had sharp cutting edges when covered in horn. Robert Bakker proposed Stegosaurus could flip osteoderms side-to-side to present predators with arrays of spikes. A 2015 study found Hesperosaurus plates were sexually dimorphic with wide plates belonging to males and taller ones to females. Buffrénil documented extreme vascularization in the outer bone layer supporting thermoregulatory theories. McWhinney's research showed 9.8% of examined Stegosaurus specimens had trauma-related damage to tail spikes. An Allosaurus vertebra was punctured perfectly by a four-foot spike entering from below, proving combat use. The sacro-lumbar expansion once thought to be a second brain now appears to function as a glycogen body or balance organ similar to birds.
Othniel Charles Marsh named Stegosaurus armatus in 1877 but it is now considered a nomen dubium due to fragmentary remains. The International Commission on Zoological Nomenclature replaced it with S. stenops as type species in 2013. Stegosaurus stenops meaning narrow-faced roof lizard was described by Marsh in 1887 from Marshall Felch's Garden Park collection. This best-known species includes at least fifty partial skeletons plus one complete skull. Stegosaurus ungulatus meaning hoofed roof lizard was named by Marsh in 1879 from Como Bluff quarry twelve near Robber's Roost. It might be synonymous with S. stenops but has longer hind limbs and proportionately smaller pointed plates. Stegosaurus sulcatus meaning furrowed roof lizard was described by Marsh in 1887 based on a partial skeleton with unusually large furrowed spikes. Maidment and colleagues proposed extensive taxonomy changes in 2008 synonymizing several species under new names like S. mjosi and S. homheni. These proposals have not been universally accepted by other researchers despite their detailed cladistic analyses.
A 2009 study examined Stegosaurus specimens of various sizes finding plates grew slower than the skeleton until maturity. Juveniles lack fusion between scapula and coracoid plus lower hind limb bones indicating immaturity. One subadult specimen discovered in Wyoming measured five meters long and weighed approximately two metric tons. A 2013 study concluded Kentrosaurus had faster growth rates than Stegosaurus contradicting general rules about larger dinosaurs growing quicker. Wiemann and colleagues published research in 2022 suggesting ectothermic or gigantothermic metabolism similar to modern reptiles. They used spectroscopy of lipoxidation signals correlating with metabolic rates across multiple dinosaur genera. Histological surveys attributed vascularization in plate microstructure to nutrient transport needs for rapid plate growth. The sacro-lumbar expansion once thought to be a second brain now appears to function as a glycogen body or balance organ similar to birds. Tracks discovered by Matthew Mossbrucker suggest Stegosaurus lived and traveled in multiple-age herds including groups of four or five babies moving together.
The Morrison Formation represents a semiarid environment with distinct wet and dry seasons plus flat floodplains. Vegetation ranged from river-lining forests of conifers and tree ferns to fern savannas with occasional Araucaria-like conifers. Animal fossils include bivalves snails ray-finned fishes frogs salamanders turtles like Glyptops sphenodonts lizards crocodylomorphs like Hoplosuchus pterosaurs such as Harpactognathus numerous dinosaur species early mammals like docodont multituberculates symmetrodonts triconodonts. Theropods living alongside Stegosaurus included Allosaurus Saurophaganax Torvosaurus Ceratosaurus Marshosaurus Stokesosaurus Ornitholestes Coelurus Tanycolagreus. Sauropods dominated the region including Brontosaurus Brachiosaurus Apatosaurus Diplodocus Camarasaurus Barosaurus Other ornithischians were Camptosaurus Gargoyleosaurus Dryosaurus Nanosaurus. Stegosaurus is commonly found at same sites as Allosaurus Apatosaurus Camarasaurus Diplodocus suggesting preference for drier settings than these contemporaries.
Auguste-Michel Jobin produced an engraving in November 1884 depicting bipedal Stegosaurus with plates along tail and back covered in speculative spikes. Charles R. Knight published his first illustration of S. ungulatus in The Century Magazine during November 1897 based on Marsh's skeletal reconstruction. This artwork later formed basis of stop-motion puppet used in 1933 film King Kong. Knight revised his version two years later producing model with staggered double row of plates under Frederic Lucas direction. Rudolph F. Zallinger painted Stegosaurus this way in Age of Reptiles mural at Peabody Museum in 1947. The U.S. National Museum commissioned paper mache models for 1904 Louisiana Purchase Exposition showing double row staggered plates. These models traveled to Portland Oregon Lewis and Clark Centennial Exposition before moving to Smithsonian National Museum Natural History Washington D.C. In December 2014 Sophie the best preserved specimen went on display after being purchased by Natural History Museum London following fundraising efforts involving private donors like Jeremy Herrmann. On the 17th of July 2024 a nearly complete twenty-seven foot skeleton nicknamed Apex fetched forty-four point six million dollars at Sotheby's auction New York City marking highest price ever paid for fossil.
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Common questions
When was Stegosaurus first described and by whom?
Othniel Charles Marsh described the first Stegosaurus fossils in 1877. Arthur Lakes found these initial bones near Morrison, Colorado.
What is the correct arrangement of Stegosaurus plates according to modern science?
Most S. stenops specimens show plates arranged in two staggered rows rather than pairs. This configuration differs from early interpretations that placed paired plates wide above the base of ribs.
Which species serves as the type species for Stegosaurus today?
The International Commission on Zoological Nomenclature replaced Stegosaurus armatus with S. stenops as the type species in 2013. Stegosaurus stenops meaning narrow-faced roof lizard was originally described by Marsh in 1887 from Marshall Felch's Garden Park collection.
How fast did Stegosaurus grow compared to other dinosaurs like Kentrosaurus?
A 2013 study concluded Kentrosaurus had faster growth rates than Stegosaurus contradicting general rules about larger dinosaurs growing quicker. Juveniles lack fusion between scapula and coracoid plus lower hind limb bones indicating immaturity until maturity.
Where did Stegosaurus live during the Late Jurassic period?
Stegosaurus lived within the semiarid Morrison Formation environment featuring distinct wet and dry seasons plus flat floodplains. Animal fossils found alongside Stegosaurus include bivalves snails ray-finned fishes frogs salamanders turtles lizards crocodylomorphs pterosaurs and numerous dinosaur species.
What price did the nearly complete Stegosaurus skeleton named Apex sell for at auction?
On the 17th of July 2024 a nearly complete twenty-seven foot skeleton nicknamed Apex fetched forty-four point six million dollars at Sotheby's auction New York City. This sale marked the highest price ever paid for a fossil.