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Useful Notes / Prehistoric Life - Ankylosaurs

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Other than the clubbed Ankylosaurus and Euoplocephalus, frequently-portrayed North American ankylosaurs include the club-less Nodosaurus, Sauropelta, Edmontonia, and (more recently) Gastonia. The European Polacanthus and Hylaeosaurus have been common sights as well because of their historical relevance, while Pinacosaurus is the most-often seen Asian ankylosaur, followed by Saichania. Among kinds found in other continents you might see Minmi from Australia, as well as a mention of the "Antarctic ankylosaur" Antarctopelta as it was the very first dinosaur found there, though it isn't often named.


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    Clubbed ankylosaurs 

Club or spikes?: Scolosaurus

  • Late Cretaceous North America has several example of dinosaurs that were very common in older popular dino-books but now have been "substituted" in their role by close relatives. The carnivorous Gorgosaurus was synonymized with Albertosaurus between the 1970s and the 2000s (though this has been reversed, and it is now a valid genus again); the hadrosaur Kritosaurus was revealed to be based upon the related Gryposaurus in the 1990s; the ceratopsid Monoclonius is today thought by several experts as a non-diagnostic juvenile centrosaur; and the small deinonychosaur Stenonychosaurus has been synonimized with Troodon since the 1980s. All this to not mentioning the notorious "Trachodon" case. The couple Scolosaurus/Euoplocephalus is the latest addition in this special list. The original specimen of Euoplocephalus was discovered in 1902, but between 1923 and 1929 three other genera very similar to it (Dyoplosaurus, Scolosaurus, and Anodontosaurus) were named. All these three were combined into Euoplocephalus in 1971, but were rescued from the Invalid Box between 2007 and 2013 after showing that some patterns of armor were useful in classifying their owners. For example, the Dyoplosaurus club was different from that of Euoplocephalus, being longer than wide, while the Anodontosaurus club had pointed ends like a giant pickaxe. Dyoplosaurus was also older than most Euoplocephalus specimens, while Anodontosaurus lived after the latter but before Ankylosaurus. But it's Scolosaurus that has been the most relevant among them. It is known from one really well-preserved skeleton from Alberta and several more incomplete specimens from Montana note . The scolosaur was about the same size as Euoplocephalus, live in the same age, had a similar head but with longer, more swept-back horns, and a club also similar in shape. The main point is: the famous armor of Euoplocephalus made of differently-shaped plates has been found to actually pertain to Scolosaurus, while the real Euoplocephalus had less complex armor. The classic "Euoplocephalus" portrayals of the 1980s and 1990s are actually based on the aforementioned well-preserved Scolosaurus found in Alberta. This skeleton, nonetheless, lacked the skull as well as the clubbed tip of its tail, making its tail look shorter and ending with a single pair of spikes (which were actually in the middle of the tail). Several old books and models have portrayed the resulting "stegosaur-tailed ankylosaur", wrongly showing it with much more generic armor than the Real Life fossil. They usually named it correctly "Scolosaurus", but sometimes "Euoplocephalus" or even "Ankylosaurus": the ur-example is the picture by Zdenek Burian which shows this critter defending itself against a Gorgosaurus. Though few noticed, even one very popular work has made the same mistake: if observed carefully, the wise "Euoplocephalus" Rooter of the original film has armor analogous to Burian's picture, and also shows the pair of spikes on the tip of its tail when he goes away, revealing he's actually based on Scolosaurus. Extra-note: Ankylosaurus magniventris and the "Euoplocephalus wastebin" have long been considered the only Late Cretaceous North American members of the club-tailed family, the Ankylosaurids. Recently, two brand-new animals from New Mexico have been found; one of them has received the name Nodocephalosaurus ("lizard with tubercled head"), resembling a Portmanteau of Nodo(saurus) and (Euoplo)cephalus plus the usual suffix -saurus.

Ankylosaurs from the East: Talarurus and "Hanwulosaurus"

  • Many more ankylosaurids are known from Asia, mostly from Late Cretaceous: Pinacosaurus is the most common in fossil record, but there were many others. Other than Saichania and Tarchia (described below), particularly worthy of note are Talarurus and the still-undescribed "Hanwulosaurus". Then, Shamosaurus and Gobisaurus, both primitive Early Cretaceous forms, their names both meaning "lizard from the Gobi Desert". Other ankies from China/Mongolia include Maleevus (named after the scientist Maleev), Sauroplites ("soldier lizard"), Shanxia, Tianzhenosaurus, Tsagantegia, Liaoningosaurus (which some believe semi-aquatic) and the deceptively-named Stegosaurides. Talarurus ("basket tail") was the second Asian ankylosaur discovered after Pinacosaurus, more precisely in the Russian expedition led by Ivan Efremov, but is much rarer than the latter; it also had a narrow head, with the typical four hornlets of ankylosaurids. Surprisingly, Talarurus has appeared at the beginning of the Disney's Dinosaur, although only with a simple unnamed cameo. Though not described yet, "Hanwulosaurus" could actually be the biggest Asian ankylosaur (9 m long): until the official description, we cannot say much more about it.

Asian Living Tanks: Saichania & Tarchia

  • Both Tarchia gigantea and Saichania chulsanensis were found in the 1970s, in the third historical expedition in Mongolia (this time led by Polish scientists). 8.5 m long, Tarchia is the biggest described Asian ankylosaur, almost as large as Ankylosaurus; Saichania too was very large (7 m). Both ankylosaurs have names that can appear funny for some: Tarchia in Mongolian means “brainy” (its first remain found was a skull with a large braincase) and Saichania in Mongolian means “beautiful” (a reference to the beauty of its well-preserved skeleton). They were the last-surviving asian ankylosaurs, and thanks to their size both should have been hard targets for every predator when adults, even for the mighty Tarbosauruses (which were less-powerful than the North American Tyrannosauruses). Also interesting is Minotaurasaurus (the "minotaur dinosaur", found only in 2009), similar to Tarchia & Saichania but with unusually-long "horns".

    Clubless ankylosaurs 

Ankylosaurs conquer the USA: Nodosaurus & "Palaeoscincus"

  • Even in Usa the first dino-discoveries included an ankylosaur, one even more incomplete than Hylaeosaurus: “Palaeoscincus” was one of the dinosaurs descibed in 1856 by Joseph Leidy from simple isolated teeth, which initially were believed from a skink-like lizard ("Palaeoscincus" means ancient skink). Many undetermined remains were later assigned to this dinosaur, making “Palaeoscincus” a Waste-Basket taxon, but now they are either regarded as dubious, or classified in other genera. The images of "palaeoscincus"es often seen in old dino-books are actually based upon another better-known ankylosaur, Edmontonia. The first North-American ankylosaur known from decent remains was Nodosaurus textilis. Described during the Bone Wars by Marsh (which also described the teeth of another relative, Priconodon), Nodosaurus ("knobbed lizard") was known only from pieces of armor with no spikes: this explains why, in classic portraits, it appears spikeless and with a generic-looking armor. Actually, the nodosaur should have had lateral spikes like its relatives. Living at the beginning of Late Cretaceous, before Edmontonia but after Sauropelta, Nodosaurus became the prototype of its own family, the Nodosaurids, in which every club-less ankylosaur used once to be put.

Ankies conquer even Canada: Edmontonia & Panoplosaurus

  • More complete nodosaurids appeared in Alberta at the start of the XX century, showing clearly spiky bodies: Panoplosaurus ("wholly-armored lizard") and Edmontonia (so-called because was found near Edmonton, see also Edmontosaurus). Both were large (6 m or so) with a complex armor expecially in the frontal portion of their body. Edmontonia showed a couple of huge shoulder-spikes pointing forwards, often double pointed, but lacked lateral spikes on its trunk and tail. Even though Edmontonia and Panoplosaurus were narrow-headed and devoid of horns or tail-clubs like all nodosaurs, they were surely a difficult task for the tyrannosaurs they shared the world with: maybe were they able yo inflict deep wounds in the carnivores' legs with their big spikes. In 1988, famous paleontologist Bob Bakker described two new dubious genera of Late Cretaceous nodosaurs, "Chassternbergia" and "Denversaurus". The first was a homage to Charles Sternberg, one of the main north-american dino-hunters from the first half of the XX century; the second owes its name from the capital of Colorado (Bakker’s state).note  Even though known for only a shattered skull, Denversaurus might have given its name to the hero of a famous TV dino-cartoon broadcast just in those years.

The Pelta Family: Sauropelta & Borealopelta

  • In the 1970s, John Ostrom (the Deinonychus Trope Namer) described an Early Cretaceous nodosaur from Montana, Sauropelta edwardsorum ("Edward's armored lizard"): Ostrom wasn’t aware of, but started the trend to name ankylosaurs with the suffix –pelta: Dracopelta, Mymoorapelta, Bissektipelta, and many others, all found later than the ur-example (except for the dubious "Stegopelta"). Also North American were Silvisaurus, Pawpawsaurus, and Texasetes, smaller relatives. Silvisaurus from Middle Cretaceous was the first discovered of the three, in the same years of Sauropelta; its name (sometimes misspelled "Silviasaurus") means "forest lizard" — the same meaning of Hylaeosaurus, but with a Latin root instead of Greek (similarly to the couple of names Ornithomimus & Avimimus). Pawpawsaurus and Texasetes were both Early Cretaceous and were found in the nineties: the former's name is not a reference to the fruit but to the formation it was dug out, while the latter's one refers to Texas. With its 7.5 long body, Sauropelta was the biggest nodosaurid known: it had a more slender body-frame than Edmontonia and Panoplosaurus, with a longer neck and smaller head; and its armor was simpler than its Late Cretaceous cousins, with small mosaic-like scutes of different size. It had nonetheless lateral spikes all along its body, and those on the shoulders were particularly long and pointing upwards - making Sauropelta a valid opponent for the contemporaneous giant theropods like Acrocanthosaurus. Typical nodosaurids had mosaic-like armor, very different to that of the ankylosaurids, made by wide rows put in line on the upper body. Found in 2008 is another nodosaur from Utah, Peloroplites ("monstrous soldier"), which was only a bit smaller than Sauropelta. Other two nodosaurians found in North America in the 1990s are Animantarx ("living citadel") and Niobrarasaurus (from Niobrara, the famous inland sea which covered the Great Plains during the Cretaceous). The most extraordinary discover about nodosaurids, however, happened in 2017 in Canada: in that year was described Borealopelta ("armor of the North"). Early Cretaceous like Sauropelta and nicknamed the Suncor Nodosaur, it uniquely preserved not only some keratinous sheaths of its armor (a bit like the skin prints of Carnotaurus) and other remains of soft tissues plus stomach contents (like the famous Edmontosaurus mummies): it has even preserved tracks of the original colors: just like many Liaoning theropods! The fossil, preserved by marine sediments, show it was probably reddish-brown in life. To date, this is the only large dinosaur which has left some tracks of its original pigmentation.

Island-dwelling Dwarf Ankylosaur: Struthiosaurus

  • The ankylosaurs found in Europe are usually like Hylaeosaurus and Polacanthus: small and clubless. To compensate, some are quite coolly-named. Acanthopholis almost seems Polacanthus inverted; "Polacanthoides" means "false Polacanthus"; Priodontognathus means "saw-toothed jaw"; Struthiosaurus means “Ostrich-Lizard” (making thinking it was Struthiomimus-like…); while Anoplosaurus means "unarmed lizard". Dracopelta is the “armored dragon”, and "Cryptodraco" the "hidden dragon". But the weirdest-named is Sarcolestes: “meat thief”. Both Sarcolestes and Dracopelta were Jurassic: Sarcolestes, found in Middle Jurassic England, was one of the first proper ankylosaurs to have evolved, living alongside the early sauropod Cetiosaurus and the large theropod Megalosaurus. Dracopelta was younger, roaming Late Jurassic Portugal along with dinosaurs more known for North America, and had already a complex armor for such a primitive ankylosaur. Acanthopholis and Anoplosaurus were Early Cretaceous kinds found in England in the XIX century, but are both known from very scant remains just like Hylaeosaurus (Anoplosaurus was often thought an ornithopod in the past). But it's Struthiosaurus the more interesting ankylosaur of Europe. It has been, indeed, not only the smallest known ankylosaur, but one of the smallest known quadrupedal dinosaurs ever (merely 6 ft, like a large dog). This because it was one of the several dwarf dinosaurs that decreased their size to survive in the islets of the Late Cretaceous Europe. Even though small, the struthiosaur was very well-protected, with a very complex armor reminescent of that of an american nodosaurid; today, scientists classify it in its own nodosaurid subfamily, the Struthiosaurines. Struthiosaurus makes also a striking example of I Have Many Names: its remains (found in several European places, among them Transilvania) were once classified in more than six genera ("Danubiosaurus" and "Crataeomus" among the others). A recent found among european ankies (2005) is Hungarosaurus from Hungary: another inhabitant of the Late Cretaceous islets but bigger than Struthiosaurus, it was the most complete European ankylosaur until the discovery in Spain of the Early Cretaceous Europelta ("european armor"), made in 2013.

The Unfair Sex: Gastonia & Mymoorapelta

  • In the 1990s, the classic “nodosaurid” / “ankylosaurid” bipartition falled down: many nodosaurids revealed not to be so-closely related with Sauropelta or Edmontonia (which, together with their closest relatives, make the Nodosaurines); among them, the “Polacanthines” or "Polacanthids" group was created to include the European Polacanthus and Hylaeosaurus (the latter could not be one of them however), and the North American Hoplitosaurus ("soldier lizard"), known since the start of the XX century from scanty remains. Some today think polacanthines were a subset of nodosaurids, but others don't agree. Just in the 1990s new, more complete polacanthines or possible polacanthines were found in USA. The first one, following the trend to name ankylosaurs with –pelta, was called Mymoorapelta in 1993: this one was the first North American ankylosaur from Late Jurassic, and lived alongside Stegosaurus Allosaurus Diplodocus etc., but today is considered by many too primitive to be a real polacanthine. Also from the same fauna was the confirmed polacanthine Gargoyleosaurus ("Gargoyle lizard"), found in 1998. Aletopelta and Cedarpelta (both found in the early 2000s) lived in the Cretaceous North America, and are considered primitive ankylosaurids but sharing also resemblances with polacanthines, leading some thinking the latter were closer to club-tailed ankylosaurs than to proper nodosaurs. The most striking polacanthine, however, was described in the same year of Gargoyleosaurus, but comes from Early Cretaceous, the Utahraptor age: Gastonia. Still another ankylosaur with the name ending in -a. Indeed this is the dino group with the greatest number of names ending so, giving them a bizarre “feminine” sound for these bulky “tanks”. Found in 1998 as well, Gastonia was clubless and medium-sized for an ankylosaur, but impressed researchers because of its armor, filled with long spikes pointing to all directions. Some people have hailed it as the most armored animal ever existed on Earth: in short, a perfect opponent for the neighboring Utahraptor. Indeed, Gastonia fights the giant dromeosaurid in the Jurassic Fight Club, and ends the battle as the victory.

Naming questions: Minmi & Antarctopelta

  • Despite this example, non-stock ankylosaurs (and stegosaurs) tend often to be ignored in visual media. Maybe their reputation of “slow and foolish” has done its part, even though this fame is undeserved. A good example of missed opportunity was a small ankylosaur discovered in Australia in 1980, with one of the least dinosaurian name one could imagine: Minmi, aka "the shortest-named dinosaur" until the 2000s. note  After a second skeleton was found in the early nineties, Minmi has since then become the most complete Australian dinosaur, even more than Muttaburrasaurus: and yet it does not appear in the Walking with Dinosaurs episode "Spirits of the Ice Forest", in which the less-complete Leaellynasaura and the “polar allosaur” appear (despite being their contemporary). Once considered nodosaurid, today Minmi paravertebra is thought a primitive, hard-to-classify ankylosaur only 10 ft long (one of the smallest known), and devoid not only of tail-club but even of prominent spikes on its body, making it a bit looking like the primitive tyreophoran Scelidosaurus. However, its torso was fully covered with small osteoderms of various shapes, its tail had plates, and could even have had some small bony scutes in its belly (a rare thing among ankylosaurs). Its main peculiarity, however, was some unusual internal bones along its backbone called paravertebras (lit. "beside vertebra"), which according to some allowed it to run faster than other ankylosaurs - hence the name Minmi paravertebra. This one was also the first ankylosaur ever found in the southern emisphere, but was steadily reached by a second animal in 1986, another primitive ankylosaur, this time discovered in Antarctica. It was the very first dinosaur ever discovered in the Ice Continent, yet has had to expect twenty years to be named: Antarctopelta appropriately. Nonetheless, the most awesome case regarding naming questions comes from Jurassic China: “Jurassosaurus nedegoapeferima”. Found in the early 1990s (when the Jurassic Park-mania began), the name was proposed by Spielberg himself, but chinese scientist Dong Zhiming discarded it, officially naming the animal Tianchisaurus nedegoapeferima. note The long, bizarre species name is formed from the surnames of the film's main stars: Sam Neill, Laura Dern, Jeff Goldblum, Sir Richard Attenborough, Bob Peck, Martin Ferrero, Ariana Richards, and Joseph Mazzello. And another asian ankylosaur was in 2002 named Crichtonsaurus for Michael Crichton. Well, ankylosaurs really have some of the most awesome names within the dinosaur world.


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