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Useful Notes / Prehistoric Life - Dinosaurs

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Dinosaurs are numerous, so it's useful to know the history of at least the most prominent ones. Of course we shouldn’t omit the more popular ones, so you’ll find references to Tyrannosaurus, Triceratops, Stegosaurus, Brontosaurus, and even some non-dinosaurs like Pteranodon, Dimetrodon, and Elasmosaurus in the folder below, other than the usual non-stock animals of the Prehistoric Life section.


    History of Dinosaur Discoveries 

EARLY-TO-MID 1800s: The first discoveries

In France in 1809, right in the middle of the Napoleonic age, Baron Georges Cuvier described the first “antediluvian reptile” note  found in Germany: the “Ptéro-dactyle” — later renamed Pterodactylus by other scientists who chose to follow the Linnaean convention of naming animals with Greco-Latin names. The fossil had actually been found decades earlier, but Cuvier was the first to give it a name. A few years later Cuvier, the father of paleontology, named the first remains of a marine reptile to be found: the “mosasaur” (Mosasaurus), whose jaws had been discovered in the Netherlands. These two creatures showed that before the “Age of Mammals” populated by mammoths, woolly rhinoceroses, cave bears, and other megafauna, which had already been known in the late 1700s, there had been an “Age of Reptiles” when wholly unfamiliar animals ruled the Earth. (Today, this time is called the Mesozoic Era.) But dinosaurs were still unknown to science. The first dinosaurs came to light about twenty years after Cuvier described Pterodactylus.

  • In England

In the middle of the 1820s, the first giant carnivorous dinosaur and the first giant herbivorous dinosaur were discovered in southern England. Known mainly from their jaws and teeth, they were respectively named Megalosaurusnote  and Iguanodon note  by the reverend and geologist William Buckland, and the surgeon Gideon Mantell. Though neither were professional paleontologists, both were aware that they had discovered something new among prehistoric animals. Mantell in particular pointed out that his Iguanodon was not a simple “giant lizard”: both species’ teeth were in sockets like those of crocodilians and mammals, and unlike those of lizards, and the Iguanodon’s were worn, showing the animal actually chewed its food, again like mammals and unlike iguanas.

When Mantell described the incomplete skeleton of a third large terrestrial reptile he named Hylaeosaurus armatusnote , it became clear that a whole community of huge land-dwelling reptiles inhabited the Earth alongside the, at the time, more familiar pterodactyls and sea reptiles whose typical representatives had been discovered before the first non-avian dinosaurs: the marine Ichthyosaurus and Plesiosaurus, and the pterosaur Dimorphodon, were found in England in the 1810s by Mary Anning, joining Pterodactylus and Mosasaurus in the paleontological repertory.

When Cuvier examined Buckland’s and Mantell’s fossils he did not recognize them as dinosaurs, for the word had not yet been coined. In the case of Iguanodon he did not even consider it a reptile — he thought it was a rhinoceros-like mammal, or even a fish! It was Richard Owen, a generation later, who created the name Dinosauria at a scientific conference in Plymouth, in 1841. Even though the word “dinosaur” literally translates into “terrible lizard”, dino- has connotations of “awe-inspiring” or “fearfully great”, and the meaning of -saurus is extended in paleontology to denote any reptile in general. Owen described dinosaurs as a subclass of the Reptilia, and called them the greatest of all the reptiles, who shared some anatomical traits with mammals.note  After the creation of the taxonomic group, Owen himself described several new genera of English dinosaurs from the 1850s to the 1880s, most of them herbivores, as the carnivores were mostly classified in the genus Megalosaurus. The best-known today include the small bipedal Hypsilophodon (which was initially believed a tree-climber, not a ground-runner), the primitive armored Scelidosaurus, the first-discovered stegosaur Dacentrurus, the spiky ankylosaur Polacanthus, and the earliest-found sauropods: the huge Cetiosaurus and Pelorosaurus. Cetiosaurus means “whale lizard”; because of its 18-meter-long backbone, and because its limbs weren’t initially found, it was believed by Owen to be another kind of marine reptile, until he himself described its limbs about thirty years later.

For information about the still-visible-today sculptures in the Crystal Palace Park made in London in year 1856 by artist Benjamin Waterhouse Hawkins, see Stock Dinosaurs: Iguanodon, Stock Dinosaurs: Megalosaurus, and Stock Dinosaurs: Hylaeosaurus. These sculptures reflected and popularized Owen’s vision of the extinct animals, in contrast with Mantell’s and Cuvier’s, not to mention that of Owen’s contemporary Charles Darwin. The park popularized several other extinct creatures besides the original three dinosaurs, usually just as inaccurately: the original marine reptiles Ichthyosaurus, Plesiosaurus, and Mosasaurus, the original flying reptile Pterodactylus, mammals of several kinds (the giant deer Megaloceros, the giant sloth Megatherium, and two species that are relatively little-known today, Anoplotherium and Palaeotherium), the Jurassic crocodilian Teleosaurus, the earliest-discovered giant amphibian "Labyrinthodon" (now Mastodonsaurus), and the first known “mammal-like reptile” Dicynodon.

  • In continental Europe

The other European country that majorly contributed to early dinosaur paleontology was Germany. Here, Hermann von Meyer described the first bones of Plateosaurus in the 1830snote , and, in the year 1861, announced to the scientific world what has since then often been celebrated as the most important fossil ever discovered: Archaeopteryx. As Darwin had announced his theory of evolution just a few years prior, Archaeopteryxnote  has been trumpeted ever since as every sort of “missing link”: between reptiles and birds, between cold-blooded and warm-blooded animals, and even between “lower” and “higher” animals, a scientifically outdated and even somewhat racist division. Even though Darwin’s colleague Thomas Henry Huxley correctly placed Archaeopteryx between dinosaurs and birds, this was proven true only in the second half of the twentieth century. Unfortunately, today it is losing its former prestige more and more, and now is considered just an ordinary feathered theropod among others.

The original Compsognathus specimen was also found in Germany in nearly the same place and time as Archeopteryx; this species was the first non-avian dinosaur to be found with a nearly complete and still-articulated skeleton, and proved that some small dinosaurs were bipedal, though the bigger ones were still considered quadrupedal by everybody at the time. Both Archaeopteryx and Compsognathus were found in the classic “death pose” with their necks turned backwards. (We still don’t know why so many dinosaurs have been found in such a position.) The example of the “compy” also shows that really small dinosaurs were already known to science well before even the big ones made their great entry into the popular culture of the twentieth century. Obviously, films and non-documentary media have usually ignored them — for example, Compsognathus had to wait 130 years until it was popularized in the 1990s by one single popular series, which portrayed it in an unrealistically overly scary way in order to make it interesting to the public.

The long-tailed pterosaur Rhamphorhynchus was found in Germany in the same site as Archaeopteryx and Compsognathusnote . The imprint of its membrane-wings ultimately demonstrated that pterosaurs were flying creatures and not terrestrial or aquatic as believed by many at the time (anyway, they were believed by most experts to be very poor flyers until the second half of the twentieth century).

In the 1870s, one of the most unexpected discoveries was made in the small country of Belgium, near the town of Bernissart: a “graveyard” of about forty Iguanodon fossils found in a coal mine. The completeness of several of the specimens made the Belgian scientist Louis Dollo able to describe this dinosaur in a more accurate way, as a bipedal critter with a kangaroo-like posture that browsed the treetops like a giraffe (and even with a giraffe-like extensible tongue). Just a few years later, other spectacular “dinosaur graveyards” would be found in the United States, and in the twentieth century still others would astonish researchers all over the world.

  • In the Americas

The first confirmed dinosaur remains to be found in the United States (and in the Americas as a whole) were single isolated teeth. These were found in the 1850s and described by the main American expert of the time, Joseph Leidy, who gave them the names Trachodon, Troodon, Palaeoscincus, and Deinodon. Deinodon was probably a tyrannosaur, Trachodon a hadrosaur, Palaeoscincus an ankylosaur, and Troodon a small carnivore. Only Trachodon and Deinodon were recognized as dinosaurs initially (as American relatives of Iguanodon and Megalosaurus respectively) while Palaeoscincus and Troodon were believed to be simple lizards (the name Palaeoscincus means “ancient skink”), and were reclassified as dinosaurs only later. In the following decades all of these genera were treated as “wastebasket taxa”, attributing other remains found later to them, which were too fragmentary to determine relation with any confidence.

The first really important dinosaur find in the country was made by fossil collector William Parker Foulke in New Jersey a few years later: the first proper dinosaur bones, mostly of the leg. They belonged to an animal related to Iguanodon and Trachodon, which Leidy named Hadrosaurus foulkiinote  in 1858. Leidy noticed that the forelimbs were much shorter and weaker than the hindlimbs, and explained this fact in the only way possible: the creature walked on just two legs. This implied that even Iguanodon should have been bipedal as well, but most scientists of the time hardly accepted that animals ten meters long and weighing multiple tons could be bipedal like birds or humans. This would also have outdated the popular quadrupedal dinosaur sculptures of Crystal Palace Park created just four years earlier in England. Hadrosaurus was the first dinosaur mounted in an exhibit; there was even a life-sized model shown in Central Park in New York (also made by Benjamin Waterhouse Hawkins) together with several other extinct animals, in an exhibition just like that of the Crystal Palace in London. Unfortunately, the statues were destroyed by the local corrupt politicians (William “Boss” Tweed and his underlings) because they didn’t make enough revenue. Their fragments were buried in Central Park, and have still not been found today.

Even though the start of American paleontology is usually put in the 1850s, some important findings had already been made in New England long before Leidy’s discoveries (around the beginning of the century), but were not initially associated with dinosaurs. Several theropod footprints of uncertain attribution were initially mistaken for tracks of a giant birdnote , and an incomplete fossil of the early dinosaur Anchisaurus was found in 1818, even before the description of Megalosaurus, but was recognized as a dinosaur only at the end of the century. note 

LATE 1800s: The Bone Wars

After the first American discoveries given above, two paleontologists from the northeastern states, Edward Drinker Cope and Othniel Charles Marsh, were attracted to the field by the great bounty of fossil material casually found in the western frontier by their collaboratorsnote . The two were initially friends, but their wishes of glory and scientific prestige caused them to become archrivals for their whole lives. They obsessively searched for the most spectacular dinosaurs possible and then quickly published whatever finds they uncovered after doing only the bare minimum of classification required, slandered each other in the media, and even hired goons to destroy each other’s discoveries! However, we have them to thank for so many dinosaurs being found in this period, including just about the most famous dinosaurs of the popular imagination. Many dinosaurian subgroupings were also created during the so-called Bone Wars, among them the theropods, sauropods, ornithopods, stegosaurs, ceratopsians, and hadrosaurs — at the time, some of these consisted solely of Bone Wars discoveries. The abundance and completeness of these remains had no equals elsewhere, not counting the Bernissart Iguanodons which were found about the same time. The controversial hypothesis of giant bipedal dinosaurs was ultimately proven true thanks to these findings, which showed that not only iguanodonts and hadrosaurs but even giant carnivores walked on two legs. However, both Iguanodon and the Bone Wars fossils were described with the classic upright stance today recognized as incorrect. This was because dinosaurs were still not thought to be related to birds (which usually keep their bodies horizontal, such as the ostrich), and so paleontologists wrongly reconstructed giant dinosaurs as though they were similar to kangaroos, with erect bodies, straight vertical necks, and lateral forelimbs. Moreover, as they were classified as reptiles, dinosaurs were also thought to have had splayed legs, dragging tails, and cheekless mouths, just like modern lizards, turtles, and crocodiles do.

One of the first animals described by Marsh was the now-obscure sauropod Atlantosaurus montanus, publicized as “the biggest creature that ever lived”, and estimated as up to 40 meters long, twice a Real Life Apatosaurus and even longer than a Real Life Diplodocus! Cope responded with his Camarasaurus supremus, also initially estimated up to 40 meters long. But it was Marsh who won the sauropod competition, describing the two most famous sauropods, Apatosaurus and Diplodocus. He was also responsible for both the notorious Brontosaurus kerfuffle and the outdated hypothesis of water-dwelling sauropods, and also the theory of sauropods/stegosaurs with a second "brain" in their hips to compensate the smallness of their proper brain. It’s worth noting that both men often discovered the same animals, but gave them different names; usually the names coined by Marsh are still valid today while Cope’s are simply invalid synonymsnote , exceptions are Camarasaurus, Coelophysis and Monoclonius, all Cope’s creations. But the Marsh names include Stegosaurus, Triceratops, and Allosaurus, as well as the horned carnivore Ceratosaurus, the ornithopods Camptosaurus and Dryosaurus, the small carnivore Coelurus, the ceratopsid Torosaurus, the ankylosaur Nodosaurus, and Ornithomimusnote , the first-known “birdlike dinosaur”, but believed to be only incidentally similar to birds and not closely related to them. Curiously, Cope described some sensational animals that are scientifically not much known today: the scrappy remains of the huge allosaur Epanterias (maybe a giant Allosaurus specimen), and the mysterious giant vertebra of Maraapunisaurus (originally in the genus Amphicoelias, this guy has recently become popular thanks to the Internet). And it was Cope who discovered the first complete hadrosaur skeletons, named Trachodon copeinote .

It’s also worth noting that some non-dinosaurs that are stock today were also found during the Bone Wars: the pterosaur Pteranodon (described by Marsh), the plesiosaur Elasmosaurus (see below), the mosasaur Tylosaurus (also described by Marsh), and the pelycosaurs Dimetrodon & Edaphosaurus (both described by Cope), as well as several extinct big mammals, such as Uintatherium and Brontotherium (both described by Leidy), the pair of proto-birds Hesperornis and Ichthyornis (both described by Marsh), and the full-bird "Diatryma" (Gastornis), described by Cope. Elasmosaurus was discovered and described by Cope slightly before the beginning of their rivalry, which was probably kicked off by the dispute over the accuracy of its reconstruction, more precisely the placement of its head. See “Heads or Tails?”.

EARLY 1900s: Dinosaurs around the world

At this time, the groups of dinosaurs that are the most familiar today (giant quadrupedal sauropods, ceratopsians, and stegosaurs, and erect giant carnivores) made their triumphant entry into the non-paleontological community. The old four-legged dragons of the Crystal Palace Park were replaced with much more diverse animals with long necks, horned heads, armored backs, upright stances, and birdlike bills. Fortunately for fiction writers, this available diversity further increased: in Europe, Asia, Africa, and especially North-America, many new dinosaurs were discovered that soon joined their elders in museums, paleo-art, and even films and cartoons. Above all, they added more material for scientists to rebuild the mosaic of dinosaur evolution. Among them, Englishman Harry G. Seeley note  was able to separate dinosaurs in two great branches: Ornithischia and Saurischia, a division which stood until 2017 (some today argue that theropods are actually closer to ornithischians than to sauropods).

  • In the United States

If we don’t count two of the greatest (in all senses) Stock Dinosaurs, Tyrannosaurus rex and Brachiosaurus (both announced just at the start of the century) the fossil sites of Eagle Land did not add many new genera to the list in the beginning of the twentieth century. Instead, several skeletons of already-known creatures were dug out in the same places where the Bone Wars were fought some decades before: e.g. the famous two Diplodocus skeletons found thanks to Carnegie’s money and enthusiasm, the “bone-quarry” in Utah full of Allosaurus dead in a prehistoric tar pit, and even a small “hut” made of sauropod bones discovered by Earl Douglass in what is today the Dinosaur National Monument (between Utah and Colorado, and a great source of Jurassic dinosaur bones even today). More spectacular was the discovery of the so-called “Trachodon mummies” which showed the first ever remains of skin and even muscles in a dinosaur fossil; but from the 1930s until recently the Bone Wars Trachodons and the mummies were rechristened Anatosaurus. Among brand-new animals described in the early 1900s were Ornitholestes (which joined Coelurus and Compsognathus among the typical small Jurassic theropods), the ceratopsid Pentaceratops found in Texas, and the latest-surviving American sauropod Alamosaurus. Among non-dinosaurian reptiles, the giant turtle Archelon was found in South Dakota slightly before the turn of the century, while the giant alligator Deinosuchus was (re-)discovered in Montana slightly after it.

  • In Canada

Alberta became the place of many new dinosaur finds ever since the discovery there of the first skull of the Tyrannosaurus relative Albertosaurus by Joseph Tyrrell at the end of the nineteenth century. The province revealed itself to be a veritable mine of Late Cretaceous dinosaurs, dramatically increasing the relatively low number of species known from the end of the Dinosaur Era. Within this context, several paleontologists competed with each other for the title of “the one who collects the best fossils”, similarly to what Cope and Marsh had done previously in the western USA (but, fortunately, not with such a hatred among them). Because of this, some have named this competition the second great dinosaur rush. The main fossil-hunters were Barnum Brown (who had found the first two Tyrannosaurus skeletons some years before), the Sternberg family, and Lawrence Lambe. The main field was the badlands around the Red Deer River not far away from Alberta’s capital of Edmonton.

These discoveries included all the main Late Cretaceous dinosaur groups, but particularly ceratopsians and hadrosaurs. The former group included the hook-frilled Centrosaurusnote , the triangle-shielded Chasmosaurus and Anchiceratops, and the spectacular multi-spiked Styracosaurus (which managed to enter the pop-culture thanks to its look), as well as the hornless Pachyrhinosaurus and the small semi-bipedal Leptoceratops — and, of course, several new specimens of Triceratops. The latter group included the huge Edmontosaurus regalis (whose name is a clear reference to Edmonton), the glove-crested Lambeosaurus lambei (named after Lambe), the allegedly hump-nosed Kritosaurus and the actually hump-nosed Gryposaurus, the dish-crested Corythosaurus and Hypacrosaurus and, most famously of all, the tube-crested Parasaurolophus; its name was in turn inspired by another hadrosaur found in these sites, Saurolophus. Moreover, there were the armored ankylosaurs, which now were definitively recognized as distinct from stegosaurs: Euoplocephalusnote , Scolosaurusnote , Panoplosaurusnote , Edmontonianote , and the prototype of the group, Ankylosaurusnote .

All these new findings enhanced the classification of dinosaurs. Ceratopsids were now separated into long-frilled and short-frilled varietiesnote . While before 1900, only non-crested kinds were known, the new hadrosaurs included both crested and crestless dinosaursnote , and some ankylosaurs such as Ankylosaurus and Euoplocephalus were revealed to have clubbed tails, unlike the Bone Wars-era Nodosaurus which was clubless, while Scolosaurus was initially believed to have had spikes on its tail due to a misinterpretation of one of its fossils. Another “small” T. rex relative, Gorgosaurusnote , was discovered at the same time. Interestingly, the Albertosaurus and Gorgosaurus fossils were more complete than those of the super-famous T. rex, often with the typical tiny two-fingered forelimbs preserved — those of Tyrannosaurus were not discovered until the 1980s! Alberta’s fossil sites also revealed smaller, slenderer animals. Among them, the first complete ornithomimosaursnote , the first incomplete “raptor” Dromaeosaurusnote  and its relative Stenonychosaurusnote , the nigh-unclassifiable small theropod Chirostenotesnote , the hypsilophodonts Thescelosaurusnote  and Parksosaurusnote , and the first pachycephalosaur to be found, Stegocerasnote , whose bulging, thickened head has long been a mystery, to the point that it has even been considered a deformity as a result of illness.

  • In Europe

The foremost European dinosaur expert was Friedrich von Huene, who divided the theropod dinosaurs into the carnosaurs (big) and the coelurosaurs (small), and discovered a huge graveyard of Plateosaurus in his native Germany, making it one of the best-known Triassic dinosaurs since, and the typical example of the new subgroup which he conceived, the prosauropodsnote , initially believed carnivorous and later herbivorous or omnivorous. Also found in Europe at the start of the twentieth century were two tiny early theropods, Procompsognathusnote  from Germany and Saltopusnote  from Scotland, the much bigger sauropod Hypselosaurus from France (which may be the owner of the biggest discovered non-avian dinosaur eggs), the sail-backed theropod “Altispinax”note , and some Late Cretaceous “dwarf dinosaurs” found mainly in Romania, including Struthiosaurus, Rhabdodon, Telmatosaurus, and Magyarosaurus. Most of these were described by another European scientist of the time, hungarian Franz Nopcsa. As well, Ornithosuchus and Saltoposuchus, both bipedal crocodylomorphs believed to be dinosaur ancestors at the time, were found in Great Britain during this period.

  • In Africa

Two animals dominated African paleontology in the early twentieth century: Spinosaurus and Giraffatitannote . The former was found in Cretaceous Sahara, but because of its fragmentary remains was originally described as a carnivore smaller than T. rex and with no interesting features other than the crest on its back, which was believed to be a sail like that of the non-dinosaurian Dimetrodon. The reconstruction as a predator bigger than T. rex (and possibly with a hump on its back) and with crocodile-like jaws came to be only in the 1990s/2000s, and that of a sea critter with tiny hindlimbs and flat tail only in the 2010s/2020s. Carcharodontosaurus was also found in Cretaceous Sahara in the early twentieth century, along with the sauropod Rebbachisaurus. It was described from even more incomplete fossils than Spinosaurusnote  as a generic carnivore only seven meters long, half the length of a Tyrannosaurus. Giraffatitan was discovered much farther south, in Tanzania, and being the first complete specimen of a brachiosaurid ever found, became the model of all the classic depictions of Brachiosaurus in popular culture. Both dinosaurs were found by German scientists (Ernst Stromer and Werner Janensch respectivelynote ) and stored in German museums; sadly, aerial bombing during the Second World War destroyed most of the Spinosaurus fossils, while the Giraffatitan is still towering firm in the Berlin Natural History Museum.

Other dinosaurs were discovered over the years in the same site as Giraffatitan (Tendaguru), all from the Late Jurassic: the small spiky stegosaur Kentrosaurus (whose pair of lateral spikes were until recently put on its hips instead of on its shoulders, and whose remains were also partially destroyed in the 2nd World War), the mysterious small carnivore Elaphrosaurus (believed at one time to be the ancestor of ornithomimosaurs), some sauropods (especially the short-necked Dicraeosaurus and another longer-necked diplodocid traditionally classified in the North American genus Barosaurus), and some dinosaurs already known from Jurassic North America (the small bipedal herbivore Dryosaurus, and perhaps even the big carnivores Allosaurus and Ceratosaurus). As a whole, the Tendaguru animals are very similar to those found in the USA during the Bone-Wars, and this was mentioned as strong evidence for Pangaea and the theory of plate tectonics.

South Africa was also the source of some early dinosaurs, such as the first fragmentary remains of the prosauropods Massospondylus and Euskelosaurus, which were among the few dinosaurian remains found in Africa before the twentieth century, and the sauropod-ancestor Melanorosaurus. But the main discoveries here were of non-dinosaurs: scientists including Robert Broom found several species living in the Early Triassic before the appearance of the first dinosaurs, including many new mammal-like reptiles, among them the very nearly mammalian Cynognathus and Thrinaxodon, and what was long believed to be an ancestor of dinosaurs, the archosauromorph Euparkeria.

  • In Asia

The first Asian dinosaur fragments were found in India, the late-surviving sauropod Titanosaurus, which was treated as a wastebasket taxon.note  The first discovery in China was of a very incomplete hadrosaur, Mandschurosaurus, in the 1920s, and later the sauropod Euhelopus in the 1930s—both found by Western, non-Chinese scientists.

Apart from these, the first really important Asian dinosaurs were discovered in Mongolia by American naturalist and adventurer Roy Chapman Andrews, who was then working for the American Natural History Museum in New Yorknote . Andrews and his team made a perilous expedition into Mongolia in the 1920s, in the middle of the Gobi Desert. Their risk was rewarded. Andrews found the first remains of what he believed to be the common ancestor of the horned dinosaurs, Protoceratopsnote . Even more importantly, the remains were found with some eggs Andrews attributed to the Protoceratops, which seemed to show once for all that dinosaurs laid eggs exactly like modern reptiles do note . Near those eggs was also found a crushed Oviraptor skull. Osborn so named it because it gave the possibility it was a specialist egg-robber, see Stock Dinosaurs. The expedition also discovered the very first incomplete Velociraptor remains, not even remotely imagining the huge recognition this name would gain 70 years later. Also discovered were the first specimens of the “parrot-bill” Psittacosaurusnote , the club-tailed Pinacosaurus (still-today the most abundant Asian ankylosaur), and the Velociraptor-relative Saurornithoides. Among non-dinosaurs the enigmatic giant mammal Andrewsarchus was also found in this expedition: its name as easily thinkable is reference to Roy Chapman Andrews.


The middle portion of the twentieth century has been nicknamed by some “the dinosaur Middle Ages” — from the wrong assumption The Middle Ages were a Dork Age of human history of course. From the 1930s to the 1960s few new species were discovered, and very few new theories about their lives were advanced. The classic image of “big stupid beasts condemned to extinction” was dominant, filling many movies and popular reconstructions of the time. If dinosaurs went extinct, it was said, it was because they were poorly adapted to their environment, and their typical features (crests, horns, plates, and so on) were considered absurd “monstrosities” without any evolutionary benefit. In short, the sentiment ran, they were simply outcompeted by the greatest and noblest lineages of the vertebrates, mammals and birds, the latter of which being believed descended directly from Triassic non-dinosaurian reptiles and not from dinosaurs at all. A good example of a snapshot about how dinosaurs were perceived by science and pop-culture at the time is visibile in 1940's Disney's Fantasia, in the "Rite of Spring" sequence.

North America supplemented the last findings of the former rush. From Wyoming came Pachycephalosaurus, the modern prototype of the thick-headed dinosaurs, in the 1940s, which were recognized as ceratopsian-relatives only in the 1980s and classically described as headbutters. Then in the 1950s, the huge allosaur Acrocanthosaurusnote  was found. In the 1960s, Edwin Colbert (who is noted also for have written the first popular informative dinosaur books) discovered the huge graveyard of Coelophysis in Ghost Ranch, New Mexico, making the genus join Plateosaurus as the most well-known early dinosaur, and advancing the hypothesis that Coelophysis was cannibalistic, since some alleged young were found inside the ribcages of some adults. In Europe, Megalosaurus was still treated as a wastebasket taxon, however, the English theropod Eustreptospondylus was split off in the 1930s. Also from this period came the description of the stegosaur Lexovisaurus, which joined Dacentrurus as one of the few European stegosaurs.

Just as interesting was the news from the Far East—the second great dinosaur hunt in Mongolia, this time led by Russian scientists such as Ivan Yefremov, discovered in the 1950s the eastern tyrannosaur Tarbosaurus bataarnote , the Asian species of the hadrosaur Saurolophus (which demonstrated that North America and Asia were united at Cretaceous times by a landbridge), the clubbed ankylosaur Talarurus, and the huge claw of Therizinosaurus.note  The expedition also found several new specimens of Protoceratopsnote  with true nests and eggs, and some new remains of Oviraptor and Velociraptor. Meanwhile in China, Yang Zhongjian, the father of Chinese paleontology, announced the first well-preserved dinosaurs found in the country: the huge-necked sauropods Mamenchisaurus and Omeisaurus, the unicorn-like hadrosaur Tsintaosaurus, the first Asian stegosaurs and carnosaursnote , and the early prosauropods Lufengosaurus and Yunnanosaurus, the former beginning the tradition of portraying dinosaurs on postage stamps. There were still also some Chinese dinosaurs described by Western scientists, namely the tiny bipedal ceratopsian Microceratops. About non-dinosaurian reptiles, the great marine reptile Kronosaurus was found in Australia in year 1924.

THE 1970s AND 1980s: The Great Renaissance

The dinosaur discovery that dominated the 1970s was undoubtedly Deinonychus, the “sickle-clawed dinosaur”, found in Early Cretaceous Montana by John Ostrom a few years prior. He described it as a cunning and vicious hunter of big game (namely the long-tailed ornithopod Tenontosaurus, also found by Ostrom), and so debunking the traditional view of dinosaurs as slow and foolish, and leading to the famous Dinosaur Renaissance led mainly by his pupil Robert Bakker. Ostrom also noted the skeletal similarities between Deinonychus and Archaeopteryx, and hypothesized that birds were direct descendants of dinosaurs and not mere relatives. As a logical consequence, many scientists started to think even some non-avian dinosaurs might have been feathered, but as there was no proof of this illustrations of the next two decades usually showed dinosaurs entirely scaled.

Meanwhile in Mongolia, the third historical expedition there, this time led by Polish scientists, among them Halszka Osmólska, uncovered the famous combat between Velociraptor and Protoceratops. The new Velociraptor remains showed it was similar to both the recently found Deinonychus and the more venerable Dromaeosaurus, so a Canadian paleontologist, Dale Russell, decided to put Deinonychus, Dromaeosaurus and Velociraptor in the same family, Dromaeosauridae.note  Another Jurassic Park dinosaur, Gallimimus, was found during the Polish expedition, as well as its relatives Archaeornithomimus, Anserimimus, Garudimimus, Harpymimus, and the huge Deinocheirus (or rather, its forelimbs). A variety of other animals were found in the expedition, among them the flat-headed pachycephalosaur Homalocephale, the extremely well-preserved skull of its relative Prenocephale, the large ankylosaurs Saichania and Tarchia, the hadrosaur-relative Probactrosaurus (which proved the duckbills’ ancestry from iguanodonts), the headache-inducing remains of the Mix-and-Match Critter Segnosaurus, the difficult-to-pronounce Opisthocoelicaudia (which was the first nearly complete skeleton of a Late Cretaceous sauropod), and a brand-new species of Oviraptor with a strange crest on its headnote . Farther south, in the People’s Republic of China, Dong Zhiming and others chinese palaeontologists started to add new dinosaurs to his precursor Yang’s collection, among them the stegosaurs Tuojiangosaurus, Wuerhosaurus, and Huayangosaurus, the carnosaur Yangchuanosaurus, the club-tailed sauropod Shunosaurus, the small ornithopod Yandusaurus, the sesquipedalian Micropachycephalosaurus, and the not nearly so sesquipedalian theropod Gasosaurus. In the 1980s, a joint Canadian-Chinese expedition found a whole herd of juvenile Pinacosaurus along the border between China and Mongolia. Also in China, in the northern province of Shandong, was found one of the biggest hadrosaurs ever, Shantungosaurus, while its much smaller relative Bactrosaurus is still today one of the few dinosaurs known from the former Soviet Union. In India, which was a huge island in the time of the dinosaurs, a very fragmentary fossil, Dravidosaurus, was wrongly publicized as the last-surviving stegosaur, while the more complete Barapasaurus, was correctly described as one of the earliest sauropods.

In Southern Africa, the curiously tusked Heterodontosaurus and the more generic Fabrosaurus and Lesothosaurus (which are perhaps the same creature) gave new light to the ornithischians’ first evolutionary steps, while new, more complete remains of Massospondylus and a newly found extremely early sauropod Vulcanodon did the same with the sauropodomorph branch. Vulcanodon was more found in Rhodesia (modern Zimbabwe), together with the smaller Coelophysis rhodesiensis- originally named Syntarsus. In Northern Africa, a sail-backed animal, the duck-billed iguanodont Ouranosaurus, joined the other more famous sailback, Spinosaurus. In Argentina, José Bonaparte discovered the first known armored sauropod, Saltasaurus, which is today the most well-known Cretaceous longneck, and the theropods Abelisaurus and Carnotaurus, the latter astonishing experts with its bullhorn-like head, tiny forelimbs, and for having revealed the best print of skin ever on a large dinosaur, as well as several other dinosaurs: the small dromeosaurid-like Noasaurus from the Cretaceous, the small hadrosaur Secernosaurus also from the Cretaceous, the sauropod and carnosaur Patagosaurus and Piatnitzkysaurus from the Jurassic, the prosauropods Riojasaurus and Mussaurus (better, the latter's eggs and newborns) from the Triassic, and many more. But the most primitive of them all, Staurikosaurus and Herrerasaurus, were not described by Bonaparte. Staurikosaurus was not even found in Argentina but in Brazil. The description of these two Middle Triassic small carnivores broke up for some time the dichotomy of saurischians versus ornithischians, as they were believed to be too primitive to belong to either. Today, they are believed to be basal saurischians. Also from the Middle Triassic was Pisanosaurus, discovered around the same time in Argentina, and still today the earliest known ornithischian.

In the United States, the Early Jurassic double-crested Dilophosaurusnote  was announced, described either as the first powerful meat-eating dinosaur or a modest carrion-eater. Its possible prey, the small, armored Scutellosaurus was also found at this time, as well as the much larger Cretaceous ankylosaurs Sauropelta and Silvisaurus, the spiky pachycephalosaur "Stygimoloch" note , the tiny oviraptorosaur Microvenator, the small hypsilophodont Othnielia rexnote , the small ceratopsid Avaceratops, the large Jurassic carnivore Torvosaurus, and the small tyrannosaur Nanotyrannusnote  among the others. Meanwhile, James Jensen revived the old tradition of ballyhooing incredibly huge sauropods to the media; his Supersaurus was briefly “the biggest dinosaur ever” until he announced the even bigger “Ultrasauros” some years later, which is now believed to be a synonym of Supersaurus. In Canada, Philip J. Currie found a huge herd of Centrosaurus that died together in a flood, giving some of the first evidence of migrating dinosaurs. He also described Stenonychosaurus as “the biggest-brained dinosaur” and a particularly smart animal — to the point his colleague Dale Russell got this Up to Eleven idea that it could have become as smart as a human had it survived the extinction. Russell also sank Gorgosaurus into Albertosaurus (but judged Daspletosaurus distinct from the latter) and separated Dromiceiomimus from Ornithomimus. But the most prominent North American paleontologist of the time was perhaps Jack Horner. In The '80s, his discovery in Montana of the nests of the hadrosaur Maiasaura (and later, those he attributed to the smaller ornithopod Orodromeus) provided hard evidence that some dinosaurs practiced parental care just like mammals and birds, representing the apex of the Dinosaur Renaissance. In England, great media coverage was dedicated to Baryonyx, nicknamed "Claws", a new kind of big theropod totally different from the others, specialized in fishing. Also in the U.K. David Norman redescribed Iguanodon, changing it from bipedal to semi-quadrupedal. On the other side of the world, the first complete Australian dinosaurs came to light; the most known is perhaps the bulge-nosed iguanodont Muttaburrasaurus, as well as the small, hard-to-classify ankylosaur Minmi, the tiny large-eyed biped Leaellynasaura, and the alleged “Australian Allosaurus”. Finally, the Ice Continent unveiled its first dinosaurs: an ankylosaur, named Antarctopelta in 2006, and an as-yet unnamed hypsilophodont, both of which were found in the ice-free part of Antarctica.

  • Great Failures of Evolution?

Other than the main discovery of parental care, several other new theories about the dinosaurs’ life and biology were proposed at this time, which made dinosaurs more similar to mammals and birds than previously thought (particularly enthusiastic about this was Robert Bakker). Land-dwelling sauropods able to lift on their hindlegs to reach high vegetation and to use their tails as whips against enemies, ceratopsids locking their horns in combat, hadrosaurs making noises to communicate to each othernote , stegosaurs using their plates as a thermoregulatory device (not defense as traditionally thought), pachycephalosaurs headbutting each other for mating purposes, mass-migration of herbivores like those of wildebeest, the possible ability to change the colors of some parts of the body, and of course the (now disputed) pack hunting of the dromaeosaurids and perhaps even of allosaurs. This does not even get into the longstanding dispute about the dinosaurs’ warmbloodedness, which is a particularly complicated argument we won’t discuss further here. We can say, however, that the abundance of herbivorous dinosaurs in respect to the carnivorous ones in many fossil sites, and the structure of dinosaurs' bones rich of passages for blood vessels, have been cited as clues of "warm-blooded" dinosaurs. The dinosaurs’ limbs became erect and pillar-like like those of elephants and birds, the bipeds’ body became horizontal, the tail became more rigid and not dragged on the ground, the ornithischians’ head received cheeks to allow the grinding-up of vegetation, and even the first portrayals of feathered theropods appeared. It was even hypothized that the success of flowering plants in the Cretaceous in respect to the other plants was due to the selective impact made by the numerous plant-eating dinosaurs of the period.

New theories about the dinosaurs’ final extinction were also advanced. The first signs of an asteroid impact appeared in the early 1980s, when the Nobel laureate Luis Alvarez discovered iridium in the rock layer of 65 million years ago. Since iridium is common in meteorites but rare on Earth, he thought this element may have come from space. The final evidence of the impact came to light around 1993, when the remains of the Chicxulub Crater were discovered in southern Mexico in the Yucatan Peninsula. The discovery of volcanic activity at the end of the Cretaceous came in the same years (the “fossilized” lava in southern India). Many of these theories made their way into the popular culture of the 1980s, an excellent example is the animated movie The Land Before Time, which shows migrating dinosaurs, parental care, terrestrial sauropods, and an extremely agile and active tyrannosaur even though the film is still partially tied with outdated theories, e.g. bipedal dinosaurs with erect bodies, water-loving hadrosaurs, splayed-legged ankylosaurs, and the mass-extinction due to changes of the Earth’s surface and not celestial bodies.

THE 1990s

In the decade of Jurassic Park the main discovery was without a doubt the first imprint of feathers found in non-avian dinosaurs, in 1996. Before then only Avimimus, found in 1981 in Mongolia, seemed to show some proof of feathers, but not prints. Then, Sinosauropteryx, Caudipteryx, Beipiaosaurus, Shuvuuia, Sinornithosaurus, and other animals found in northern China/Mongolia changed the perception of dinosaurs, which were much more birdlike than usually thought. Today, dozens of feathered dinosaurs are known, as well as some animals which have had some relation with the bird-dinosaur argument — the north-american alleged “first bird” Protoavis in 1990; the mongolian Mononykus in 1993, a small one-fingered theropod which was initially believed to be a true bird; and Confuciusornis, a true bird of China with three hand-fingers like a non-bird theropod. What also determined the scientific perception of dinosaurs was the coming of the revolutionary cladistic method of classification which partially superseded the traditional Linnaean method. Cladistics has proven especially useful for the classification of theropods, for example by changing the traditional division into carnosaurs and coelurosaurs started in the beginning of the XX century into something much more complex.

In North America, the diplodocid “Seismosaurus” competed with “Ultrasauros” in the early 1990s for the title of biggest land animal ever; today, both names are considered invalid by the official scientific community. Meanwhile, the first really complete Tyrannosaurus rex skeletons, even with forelimbs and the end of the tail, were found in the USA: notably “Sue”, the biggest known Tyrannosaurus fossil until few years ago, which was found on a Native American reservation and temporarily impounded by the Sioux. The traditional Anatosaurus was divided into Edmontosaurus and “Anatotitan” in 1990, but the latter was later sunk back into the former. A huge herd of another hadrosaur, the crested Hypacrosaurus, was found soon later. The discovery of Utahraptor scaled up dromaeosaurid size from 3 to 7 meters long in 1993; in the same year the first Jurassic north-american ankylosaur was described, Mymoorapelta, followed by the contemporary Gargoyleosaurus and the Early Cretaceous Gastonia in 1998, the latter with a complex armor. Gojirasaurus was the first large theropod found in Triassic North-America, living alongside Coelophysis. It was also confirmed that even Alaska was populated by dinosaurs: the ceratopsid Pachyrhinosaurus was revealed in the 1990s in a huge fossil herd near the Polar Circle. Also found in the most northern portions of North America already in the eighties were hadrosaurs like Edmontosaurus and Parasaurolophus and theropods like tyrannosaurids and Troodon. The existence of North and South polar dinosaurs were cited as another possible proofs of warmbloodedness. Also found in this decade were the specialized ceratopsians Achelousaurus and Einiosaurus and the much more primitive Zuniceratops, the earliest North-American ceratopsian with only the two brow-horns.

As for the other continents, South America was particularly fruitful: the tiny Eoraptor, long believed to be the first-ever dinosaur, in 1993; the spiny-backed sauropod Amargasaurus in 1990; the nesting ground attributed to Saltasaurus in 1998; and the incomplete remains of the titanosaur Argentinosaurus, which took the “biggest ever!” title, now contended by other sauropod species, notably the north-american Sauroposeidon, the mysterious Maraapunisaurus ("Amphicoelias fragillimus"), and possibly Barosaurus, other than several newer titanosaurs worldwide like Puertasaurus or Paralititan, and the presumed "Bruhathkayosaurus" of India. Slightly later in Argentina was found Giganotosaurus that, together with the new remains of Carcharodontosaurus, was presented as “bigger than T. rex”: today the record-holder among theropods is officially Spinosaurus, redescribed in the 1990s as more similar to the fishing Baryonyx & Suchomimus (the latter found in the 1990s in the Sahara like the spinosaur) than to Tyrannosaurus or Allosaurus.

In Mongolia, Oviraptor, or rather, Citipati, was revealed not to be an egg-thief as traditionally thought, but an egg-nurse; and Therizinosaurus revealed not to be a gigantic predator but a herbivorous relative of Segnosaurus, thanks to the discovery of one much smaller relative of both, Alxasaurus. In China the small stegosaur Gigantspinosaurus showed huge shoulder-spikes, while Tianchisaurus was the first Jurassic asian ankylosaur found, initially named "Jurassosaurus" from Jurassic Park. Always in China, the middle-sized theropod Monolophosaurus showed a straight cranial crest, similar to Dilophosaurus. In England, the carnosaur Neovenator was found living alongside Iguanodon and Hypsilophodon in Early Cretaceous Isle of Wight. In Italy, the tiny theropod Scipionyx (the first dino found here) preserved the very first internal organs in a dinosaur-fossil, and even tracks of cells; though the alleged “heart” of the ornithopod Thescelosaurus found a bit later in the USA is probably a simple piece of stone that looks superficially heart-like. In Spain, the small ostrich-dinosaur Pelecanimimus revealed a throat pouch like a pelican's, possibile feathers, and many tiny teeth in the mouth. In Madagascar, Majungasaurus (found 80 years before) revealed not to be a small pachycephalosaur but a large one-horned theropod similar to Carnotaurus. Again in Sahara, Deltadromeus was a kind of Cretaceous theropod found near the carcharodontosaur, apt for running. Last example, in Antarctica, a middle-sized theropod, the Jurassic Cryolophosaurus, was found with a curly crest on its eyes, and was nicknamed "Elvisaurus" from Elvis Presley.

THE 2000s

The Turn of the Millennium opened with an unexpected find in northern China: a four-winged dromaeosaurid, named Microraptor, which demonstrated once and for all that birds are dinosaurs. Later, also in China, some paleontologists began the trend of naming Chinese dinosaurs with the suffix “-long”: e.g. the rex-ancestors Guanlong and Dilong (the first crested, the second feathered), and the trike-ancestor Yinlong, the earliest known ceratopsian. Meanwhile, the miniseries Walking with Dinosaurs, the mockumentary Prehistoric Park, and Disney's Dinosaur popularized some new theories about dinosaur life thanks to advanced computer graphics, such as rigid-necked sauropods. Other theories that emerged from computerized studies or re-study of fossil bones include non-headbutting pachycephalosaurs, non-pack-hunting dromaeosaurids, non-quadrupedal prosauropods, non-cannibalistic Coelophysis, and filter-feeding ornithomimids (the latest one now discarded). Several new interesting dinosaurs were found: among them, Gigantoraptor, a huge oviraptorosaur from Mongolia; Megaraptor, an Argentinian carnivore with large hand-claws (found sligtly before year 2000 but recognized as a handclaw in the decade); Masiakasaurus, a small Malagasy carnivore with protruding teeth; Mei long, a Chinese troodontid found in a sleeping pose; Sinornithomimus, a small Chinese ostrich-dinosaur with gastroliths preserved in its belly; Nqwebasaurus, the oldest known Southern coelurosaur; Mapusaurus and Tyrannotitan, both South-American relatives of Giganotosaurus and Carcharodontosaurus; Miragaia, a long-necked stegosaur from Jurassic Portugal; Olorotitan, an asian hadrosaur with an axe-shaped crest on its head; Charonosaurus, the Asian equivalent of Parasaurolophus; Albertaceratops and Eotriceratops, an archaic ceratopsid rather in the middle between the two subgroups of the family the first, a huge Triceratops early cousin the second; the spiky-headed "Dracorex", likely a juvenile and/or female Pachycephalosaurus; Eotyrannus, the "dawn tyrannosaur" of Cretaceous England; Eocursor, the "dawn runner" of Triassic Africa and the first complete triassic ornithischian; Tethyshadros, the most complete European hadrosaur; Oryctodromeus, a small North American ornithopod that revealed the first proof of a burrowing dinosaur; Nothronychus and Falcarius, North-American therizinosaurs, the first big and evolved, the second small and primitive; some odd sauropods, namely the giraffe-like titanosaur Isisaurus, the short-necked diplodocoid Brachytrachelopan, the multi-toothed diplodocoid Nigersaurus, the beaked Bonitasaura, the spiny Spinophorosaurus, and the huge primitive Turiasaurus; Glacialisaurus, a "prosauropod" that was the first sauropodomorph found in Antarctica; Aerosteon, a big theropod with extensive airsacs in its bones; the scansoriopterygids, tiny Asian theropods with huge hand-fingers apt to climb trees; Anchiornis, another tiny feathered birdlike theropod of Asia with the plumage colors very well-preserved; and perhaps the most surprising one, Tianyulong, the first ornithischian found with feather-things. In the 2000s the most interesting fact about dinosaurs regarded indeed their skin; it appeared that not only theropods, but also herbivorous dinosaurs were covered in some sort of feathers or featherlike structures. The quills on the tail of Psittacosaurus found in China in 2001 and the fleshy spikes of Diplodocus found in the 1990s in North America could have had the same origins of theropods’ feathers, as maybe demonstrated by the discovery of the tiny feathered heterodontosaurian Tianyulong in 2009, always in China. In the same year, Giraffatitan was definitively recognized as distinct from Brachiosaurus. In the decade the early sauropodomorph Massospondylus revealed rich nesting grounds in Africa similar to those of Maiasaura in North America.

Interestingly, one close dinosaur relative, the pterosaur Sordes, had revealed signs of hair-like pycnofibres already in the 1970s. Speaking of pterosaurs, they too have undergone a renaissance since the 1970s. The huge Quetzalcoatlus and several others (Dsungaripterus, Pterodaustro, the Early Triassic Eudimorphodon, and more) greatly increased the known variety, showing that flying reptiles were as ecologically diverse as modern birds, and just as efficient fliers. Since Eudimorphodon lived at the same time of the first dinosaurs and Quetzalcoatlus at the extreme end of the Mesozoicnote , it became clear that pterosaurs inhabited the Earth across the whole Age of Dinosaurs, from roughly 228 to 66 million years ago. In addition, the foot-long Lagosuchus found in the 1970s in Argentina has demonstrated the evolutionary link between pterosaurs and dinosaurs. Other Mesozoic animals found since the 1970s worthy of note include the huge triassic ichthyosaur Shonisaurus found in North America; the giant crocodilian Sarcosuchus found in Cretaceous african Sahara, which like its relative Deinosuchus may have been able to turn large dinosaurs into its meals; Lisowicia, a plant-eating dicynodont (a type of mammal-ancestor) of the late Triassic the size of an elephant — twice the size of the biggest previously-known mammal-ancestors; and the early Cretaceous mammals Sinodelphys and Eomaia, found with tracks of fur around their skeletons and briefly considered "the first marsupial" and "the first placental" respectively.

THE 2010s

In general, the discoveries of The New '10s have confirmed the scientific intuitions made in the previous decade. New feathered theropods and non-theropods were described each year, and even some classic dinosaurs like Velociraptor and Ornithomimus have yielded some imprinting of feathers. Dozens of new dinosaur genera used to be described each year, a much greater rate than ever before — to give some idea, before the 1980s it was rare that more than two or three new dinosaur kinds were discovered in a year. But note that many recent genera are described from only a few pieces of bone and no more. Theories about dinosaur lifestyles flourish and contradict each other, and the dinosaurs’ evolutionary tree is relentlessly modified by new discoveries and studies, all under the rules of cladistics. There have not been too many sensational discoveries in this decade, but there have been some surprises here and there: most notably, the sudden increase in number of the known ceratopsian genera since 2010; the finding in the same year of Concavenator , a humped-backed theropod with some possible signs of feathers, and the surely-feathered theropods Sciurumimus and Yutyrannus in 2012, which showed feathers being older and more widespread than what was previously supposed; the first complete skeletons of the classically enigmatic Deinocheirus in 2014 which revealed it to be a very specialized & unique theropod; the correct interpretation of the crest of the asian hadrosaur Tsintaosaurus; the reclassification of several early jurassic coelophysoids in the classic genus Coelophysis; the rebuilt of Spinosaurus as a quadrupedal and/or marine animal with tiny hindlimbs and flat "finned" tail to swim like a croc; the definitive classification of the alleged last-stegosaur Dravidosaurus as a swimming sea-reptile; the finding of another fossil herd of the ceratopsian Centrosaurus in North America, even huger than the graveyard found in Alberta in the eighties; the finding in Argentina of the spiky-necked sauropod Bajadasaurus and the huge titanosaur Dreadnoughtus; the extremely well-preserved remain in Canada of the ankylosaur Borealopelta, with the tracks of the animal's original soft tissues, stomach contents, and even colors; the discovery in China of Yi qi, a tiny feathered scansoriopterygid theropod with batlike wings; and, perhaps the most significant to this wiki, the resurrection of the name Brontosaurus as a valid taxon in 2015.

THE 2020s

The New '20s have just begun; for now, there are not much many discoveries about dinosaurs — only a continuation of the studies of the previous decade and a few new kinds added in the list. Of note, however, are the current re-description of Dilophosaurus, the confirmation of the "swimming fin-tailed Spinosaurus" theory, and the finding in Antartica of a giant egg from Cretaceous, probably belonging to a non-dinosaur marine reptile - arguably a mosasaur. This possibly shows mosasaurs were egg-layers like many modern lizards and snakes, rather than live-bearers.

Here are the non-stock dinosaurs divided in subgroups according to their real relationships, and sometimes their external appearances.


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