page_title: Stegosaurus
section_title: Discovery and history
hierarchical_section_title: Stegosaurus / Discovery and history
caption_attribution_description: Illustration of Stegosaurus ungulatus
context_page_description: Stegosaurus, from Greek stegos which means roof and sauros which means lizard, is a genus of herbivorous thyreophoran dinosaur. Fossils of this genus date to the Late Jurassic period, where they are found in Kimmeridgian to early Tithonian aged strata, between 155 and 150 million years ago, in the western United States and Portugal. Of the species that have been classified in the upper Morrison Formation of the western US, only three are universally recognized; S. stenops, S. ungulatus and S. sulcatus. The remains of over 80 individual animals of this genus have been found. Stegosaurus would have lived alongside dinosaurs such as Apatosaurus, Diplodocus, Brachiosaurus, Allosaurus, and Ceratosaurus; the latter two may have preyed on it.
  These were large, heavily built, herbivorous quadrupeds with rounded backs, short fore limbs, long hind limbs, and tails held high in the air. Due to their distinctive combination of broad, upright plates and tail tipped with spikes, Stegosaurus is one of the most recognizable kinds of dinosaurs. The function of this array of plates and spikes has been the subject of much speculation among scientists.
context_section_description: Stegosaurus, one of the many dinosaurs first collected and described in the Bone Wars, was originally named by Othniel Charles Marsh in 1877, from remains recovered north of Morrison, Colorado. These first bones became the holotype of Stegosaurus armatus. Marsh initially believed the remains were from an aquatic turtle-like animal, and the basis for its scientific name, 'roof(ed) lizard' was due to his early belief that the plates lay flat over the animal's back, overlapping like the shingles (tiles) on a roof. A wealth of Stegosaurus material was recovered over the next few years, and Marsh published several papers on the genus from 1877 to 1897. In 1878, Edward Drinker Cope named Hypsirhophus discurus, as another stegosaurian based on fragmentary fossils specimens from Cope's Quarry 3 near the "Cope's Nipple" site in Garden Park, Colorado. Many later researchers have considered Hypsirhophus to be a synonym of Stegosaurus, though Peter Galton (2010) suggested that it is distinct based on differences in the vertebrae.
  Marsh named a second species, Stegosaurus ungulatus, in 1879, and finally gave a more detailed description of all the Stegosaurus fossils collected to far the following year. In 1881, he named a third species Stegosaurus "affinis", based only on a hip bone. This species is generally agreed to have been inadequately described, and therefore is a nomen nudum (a name lacking a formal description). The specimen was later lost. Marsh continued to collect and examine new Stegosaurus specimens, and in 1887 he named three new species: Stegosaurus stenops, S. duplex, and S. sulcatus. Though it had not yet been completely prepared, the nearly complete and articulated type specimen of Stegosaurus stenops allowed Marsh to complete the first attempt at a reconstructed Stegosaurus skeleton. This first reconstruction, of S. ungulatus with missing parts filled in from S. stenops, was published by Marsh in 1891. (In 1893, Richard Lydekker mistakenly re-published Marsh's drawing under the label Hypsirhophus).
  The next species of Stegosaurus to be named was S. marshi, by Frederick Lucas in 1901. Lucas reclassified this species in the new genus Hoplitosaurus later that year. Lucas also re-examined the issue of the life appearance of Stegosaurus, coming to the conclusion that the plates were arranged in pairs in two rows along the back, arranged above the bases of the ribs. Lucas commissioned Charles R. Knight to produce a life restoration of S. ungulatus based on his new interpretation. However, the following year, Lucas wrote that he now believed the plates were probably attached in staggered rows. In 1910, Richard Swann Lull wrote that the alternating pattern seen in S. stenops was probably due to shifting of the skeleton after death. He led the construction of the first ever Stegosaurus skeletal mount at the Peabody Museum of Natural History, which was depicted with paired plates. In 1914, Charles Gilmore argued against Lull's interpretation, noting that several specimens of S. stenops, including the now-completely prepared holotype, preserved the plates in alternating rows near the peak of the back, and that there was no evidence of the plates having shifted relative to the body during fossilization. Gilmore and Lucas' interpretation became the generally accepted standard, and Lull's mount at the Peabody Museum was changed to reflect this in 1924.
  Sophie the Stegosaurus is the most nearly complete fossil specimen of a Stegosaurus. It is a young adult of undetermined sex, 5.6 metres (18 ft) long and 2.9 metres (9.5 ft) tall. The specimen, which was found in Wyoming, is 85% intact, containing 360 bones. It was put on display at the Natural History Museum, London in December 2014.
caption: Marsh's 1891 illustration of S. ungulatus: Note the single row of 12 large rounded plates, based on those of S. stenops, and eight spikes
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