Line #19 UsefulNotes/PrehistoricLifeStegosaurs


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3	[[quoteright:220:https://static.tvtropes.org/pmwiki/pub/images/220px_tuojiangosaurus_skeleton_nhm.JPG]][[caption-width-right:220:BewareMyStingerTail.]]
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5	Stegosaurs have always been one of the dinosaur groups with very few species described (the same cannot be said of their relatives the ankylosaurs). This explains the shortness of this page despite the fame of the stegosaurs.
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7	Note that all the examples below are found outside North America; indeed, only ''one'' kind of stegosaur is known definitively to come from this landmass, the ever-popular ''[[UsefulNotes/StockDinosaursOrnithischianDinosaurs Stegosaurus]]''. Another North American genus was described in the 2000s, the round-plated ''[[http://en.wikipedia.org/wiki/Hesperosaurus Hesperosaurus]]'' ("western lizard"), but it could be another ''Stegosaurus'' species. A third genus, "Diracodon", was named during the Bone Wars, but now is regarded as an invalid synonym of ''Stegosaurus''.
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9	Among non-''Stegosaurus'' stegosaurs, you will see ''[[UsefulNotes/StockDinosaursOrnithischianDinosaurs Tuojiangosaurus]]'' (the animal of the image) and ''[[UsefulNotes/StockDinosaursOrnithischianDinosaurs Kentrosaurus]]'' more often than others, but you could also see ''Dacentrurus'', ''Huayangosaurus'', ''Wuerhosaurus'', ''Lexovisaurus'', ''Gigantspinosaurus'', ''Miragaia'', and others, as well as getting the occasional mention of "''Dravidosaurus''".
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15	[[folder:Non-Stock Stegosaurs]]
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19	'''Bigger than Stegosaurus?:''' ''[[http://en.wikipedia.org/wiki/Dacentrurus Dacentrurus]]''
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21	* ''Dacentrurus armatus'' was first described in the mid-1800s by Richard Owen with the now-invalid name "Omosaurus", before ''Stegosaurus'' itself was discovered in the USA: it was indeed the very first stegosaur discovered by science, but was put in the ''Stegosauria'' only after the description in North America of the genus ''Stegosaurus''. Unfortunately, the dacentrurus is known from incomplete remains, so its appearance and even its size are uncertain. Illustrations usually show it with a kentrosaur-like armor (with or without shoulder-spikes). Some however suspect ''Dacentrurus'' was a very large animal, maybe even bigger than ''Stegosaurus'' itself, which is usually considered the largest stegosaur; but we need more fossils to prove it true.
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25	'''Cousins in Europe:''' ''[[http://en.wikipedia.org/wiki/Lexovisaurus Lexovisaurus]]'' & ''[[http://en.wikipedia.org/wiki/Loricatosaurus Loricatosaurus]]''
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27	* Three similar-looking stegosaurs are known from Middle Jurassic Europe. Both ''Dacentrurus'' ("tail full of points") described above, and ''Lexovisaurus'' (named from an ancient Celtic people) are found in several European countries: England, France, and Portugal. ''Lexovisaurus durobrivensis'' was named in the 20th century. Sadly, ''Lexovisaurus'' too is known from scanty remains. Illustrations usually show it with the same kentrosaur-like look of ''Dacentrurus'', even though the lexovisaur sometimes appears with a more tuojiangosaur-like look. Recently, many alleged "Lexovisaurus" remains have been reclassified in another genus, ''Loricatosaurus'' ("armored lizard"), almost-identical to the former.
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31	'''How Many Plates You Have:''' ''[[http://en.wikipedia.org/wiki/Miragaia_(dinosaur) Miragaia]]''
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33	* But in 2009, a brand-new stegosaur was excavated in Portugal: the quite simple-named but very peculiar ''Miragaia''. Late Jurassic like ''Stegosaurus'', ''Kentrosaurus'' & ''Tuojiangosaurus'', it was medium-sized for a stegosaur, and with its small but abundant plates and unusually long neck, it looks a bit like Dinny from ''ComicStrip/AlleyOop''. Its full scientific name is ''Miragaia longicollum'', the latter term meaning "long necked" indeed. ''Miragaia'' suddenly increased the diversity of the small taxonomic group of the stegosaurs: before its discovery all stegos were believed to have had the same short-necked shape of ''Stegosaurus''. ''Miragaia'' has already appeared in [[Series/DinosaurRevolution one TV documentary]], and its unusual look could even make it interesting for pop-cultural producers, either.
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37	'''MOAR cousins, this time in China:''' ''[[http://en.wikipedia.org/wiki/Chialingosaurus Chialingosaurus]]'' & ''[[http://en.wikipedia.org/wiki/Chungkingosaurus Chungkingosaurus]]''
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39	* The People's Republic of China has given us about half the steggies around the world. ''Chialingosaurus'' was the first discovered, in 1940s: Late Jurassic, it was similar to ''Kentrosaurus'' and more slender than other stegosaurs. The others have been found since the 1970s: other than ''Tuojiangosaurus'' there are the Middle Jurassic ''Huayangosaurus''; the small ''Chungkingosaurus'' (Late Jurassic); ''Jiangjunosaurus'', which was found in the western region of Xinjiang; ''Monkonosaurus'', found in Tibet; the Middle Cretaceous ''Wuerhosaurus''; and ''Yingshanosaurus'', with flattened shoulder-spikes.
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43	'''Immense Spikes:''' ''[[http://en.wikipedia.org/wiki/Gigantspinosaurus Gigantspinosaurus]]''
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45	* A find from the 1990s has received a more obvious name: ''Gigantspinosaurus'' (it was not a cross between [[UsefulNotes/StockDinosaursSaurischianDinosaurs a ''Giganotosaurus'' and a ''Spinosaurus'']]!) Kentrosaurus-sized, thus small for stegosaur standards, it had small plates oddly only on its back (not on its tail) and an incospicuous thagomizer: both features vividly contrast with its truly [[ExactlyWhatItSaysOnTheTin gigantic spines]] on its shoulders: thick, curved, and each as long as the whole trunk! Like ''Miragaia'' above, ''Gigantspinosaurus'' has notably increased the variety of the stegosaur world thanks to its look, and its colossal shoulder-spikes could even make it interesting for the broader pop-culture.
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49	'''Primitive and Scelidosaurus-like:''' ''[[http://en.wikipedia.org/wiki/Huayangosaurus Huayangosaurus]]''
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51	* ''Huayangosaurus'' is particularly notable among stegosaurians in general, because it's the most primitive stegosaur known from good fossil material (''[[http://en.wikipedia.org/wiki/Tatisaurus Tatisaurus]]'' from Early Jurassic was once believed an even more basal stegosaur from Yunnan, but is known only from pieces of bone and it's more likely a scelidosaur instead). ''Huayangosaurus'' was small, 4 m long, and preserved several ancestral traits in its skeleton, such as a big head, small frontal teeth on its upper jaw, and long forelimbs. The frontal upper teeth are a typical primitive trait among ornithischians, which were lost in more evolved stegosaurs. The huayangosaur's armor, however, was already fully stegosaurian, rather similar to ''Tuojiangosaurus'' with a true thagomizer, and also with shoulder spikes like ''Kentrosaurus''. Because of their primitiveness, ''Huayangosaurus'' and few others, like ''Chungkingosaurus'' and the little-known ''Craterosaurus'' and ''Regnosaurus'', both from Early Cretaceous England, make a family on their own, Huayangosaurids, while most other stegosaurs make together the more evolved Stegosaurids.
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55	'''Evolved and Stegosaurus-like:''' ''[[http://en.wikipedia.org/wiki/Wuerhosaurus Wuerhosaurus]]''
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57	* At the other extremity, ''Wuerhosaurus'' was one of the latest-surviving stegosaurs, and the most known among the Cretaceous stegosaurs in spite of being scantier than several Jurassic relatives. Almost as large as a ''Stegosaurus'', it had the same alternate plates and four-spiked tail, but has traditionally been depicted with very low, rectangular plates instead of pentagonal. According to recent research its plates could have been taller and more ''Stegosaurus''-like than formerly thought. We don't know if it had shoulder spikes or not, but flat bony skin-scutes are known from fossils.
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61	'''Stegosaur History'''
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63	* Definitive stegosaurs appeared in the Middle Jurassic: ex. ''Huayangosaurus'', ''Dacentrurus'', ''Lexovisaurus'', the north-African ''[[http://en.wikipedia.org/wiki/Adratiklit Adratiklit]]'', and the currently most ancient known, ''[[http://en.wikipedia.org/wiki/Bashanosaurus Bashanosaurus]]'' described in 2022 in China. They reached their heyday in the Late Jurassic with genera such as ''Stegosaurus'', ''Tuojiangosaurus'', ''Kentrosaurus'', ''Chialingosaurus'', ''Gigantspinosaurus'', ''Miragaia'', and several others. However, they began to decline in Early Cretaceous, perhaps due to competition from the more armored ankylosaurs, yet there were still a few holdouts such as ''Wuerhosaurus'' and the African ''[[http://en.wikipedia.org/wiki/Paranthodon Paranthodon]]''.
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67	'''Under The Sea?:''' ''[[http://en.wikipedia.org/wiki/Dravidosaurus Dravidosaurus]]''
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69	* However, there was a stegosaur which, uniquely, survived until the Late Cretaceous: ''Dravidosaurus''. Discovered in 1979, it's one of the few dinosaurs (and the only stegosaur) found in Indian subcontinent (the leg bone of ''Brachypodosaurus'' was also found there, but it's uncertain if it was a stegosaur or an ankylosaur), a huge separate landmass in the Late Mesozoic. ''Dravidosaurus'', whose name could be translated to "lizard of Southern India", somehow managed to arrive there, and flourished thanks to the absence of competition which other relatives faced in the mainland. Its status as "the last stegosaur" gave it several mentions in books and even some documentaries, which usually showed it like an undersized "Stegosaurus" (it was believed one of the smallest stegosaurs ever). However, all this was [[ScienceMarchesOn shown to be false]] in 1996. In that year, a re-examination of its extremely fragmentary remains has revealed our Last Stegosaur to be 1. not a stegosaur, 2. not a dinosaur, and 3. not even a land-dweller. It was a marine reptile, more precisely a [[UsefulNotes/PrehistoricLifeNonDinosaurianReptiles plesiosaur]]. However, in 2017, some experts have still argued that the dravidosaur was actually the "last stegosaur", and the enigma is still unresolved. Today, ''Dravidosaurus'' is classified as a reptile "''incertae saedis''" (Latin for "uncertain placement").
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Context UsefulNotes / PrehistoricLifeStegosaurs