For millennia, humans have discovered dinosaur remains, which have most likely contributed to belief in mythical beasts such as dragons. A few dinosaur bones were depicted in old European publications, but their true nature was never revealed. The claim in the Genesis creation story that the planet and all life were formed just two thousand years before the pyramids were built hampered scientific research into fossils in the West. The numerous three-toed trackways discovered in New England at the beginning of the 1800s were attributed to large birds. The growing geological evidence that Earth's history was much more complex and extended back into deep time by the early 1800s began to free researchers to consider the possibility that long-extinct and exotic animals once roamed the globe.
Modern dinosaur paleontology began in the 1820s in England. Teeth were found, and a few bones of the predatory Megalosaurus and herbivorous Iguanodon were published and named. For a few decades it was thought that the bones coming out of ancient sediments were the remains of oversized versions of modern reptiles. In 1842 Richard Owen recognized that many of the fossils were not standard reptiles, and he coined the term “Dinosauria” to accommodate them. Owen had pre-evolutionary concepts of the development of life, and he envisioned dinosaurs as elephantine versions of reptiles, so they were restored as heavy-limbed quadrupeds. This led to the first full-size dinosaur sculptures for the grounds of the Crystal Palace in the 1850s, which helped initiate the first wave of dinomania as they excited the public. A banquet was actually held within one of the uncompleted figures. These marvelous examples of early dinosaur art still exist.
The first complete dinosaur skeletons, uncovered in Europe shortly before the American Civil War, were those of small examples, the armored Scelidosaurus and the birdlike Compsognathus. The modest size of these fossils limited the excitement they generated among the public. Found shortly afterward in the same Late Jurassic Solnhofen sediments as the latter was the “first bird,” Archaeopteryx, complete with teeth and feathers. The remarkable mixture of avian and reptilian features preserved in this little dinobird did generate widespread interest, all the more so because the publication of Charles Darwin’s theory of evolution at about the same time allowed researchers to put these dinosaurs in a more proper scientific context. The enthusiastic advocate of biological evolution Thomas Huxley argued that the close similarities between Compsognathus and Archaeopteryx indicated a close link between the two groups. In the late 1870s Belgian coal miners came across the complete skeletons of iguanodonts that confirmed that they were three-toed semibipeds, not full quadrupeds.
At this time, the action was shifting to the United States. Before the Civil War, incomplete remains had been found on the Eastern Seaboard. But matters really got moving when it was realized that the forest-free tracts of the West offered hunting grounds that were the best yet for the fossils of extinct titans. This quickly led to the “bone wars” of the 1870s and 1880s in which Edward Cope and Charles Marsh, having taken a dislike for one another that was as petty as it was intense, engaged in a bitter and productive competition for dinosaur fossils that would produce an array of complete skeletons. For the first time it became possible to appreciate the form of classic Late Jurassic Morrison dinosaurs such as agile predatory Allosaurus and Ceratosaurus, along with Apatosaurus, Brontosaurus, Diplodocus, and Camarasaurus—which were really elephantine quadrupeds—the protoiguanodont Camptosaurus, and the bizarre plated Stegosaurus. Popular interest in the marvelous beasts was further boosted.
By the turn of the century, discoveries shifted to younger deposits such as the Lance and Hell Creek, which produced classic dinosaurs from the end of the dinosaur era including duck-billed Edmontosaurus, armored Ankylosaurus, horned Triceratops, and the great Tyrannosaurus. As paleontologists moved north into Canada in the early decades of the twentieth century, they uncovered a rich collection of slightly older Late Cretaceous dinosaurs including Albertosaurus, horned Centrosaurus, spiked Styracosaurus, and the crested duckbills Corythosaurus and Lambeosaurus. Inspired in part by the American discoveries, paleontologists in other parts of the world looked for new dinosaurs. Back in Europe abundant skeletons of German Plateosaurus opened a window into the evolution of early dinosaurs in the Late Triassic. In southeastern Africa the colonial Germans uncovered at exotic Tendaguru the supersauropod Giraffatitan (was Brachiosaurus) and spiny Kentrosaurus. In the 1920s Henry Osborn at the American Museum in New York dispatched Roy Andrews to Mongolia in a misguided search for early humans that fortuitously led to the recovery of small Late Cretaceous dinosaurs, parrot-beaked Protoceratops, the “egg-stealing” Oviraptor, and the advanced, near-bird theropod Velociraptor. Dinosaur eggs and entire nests were found, only to be errantly assigned to Protoceratops rather than the oviraptorid that had actually laid and incubated them. As it happened, the Mongolian expeditions were somewhat misdirected. Had paleontologists also headed northeast of Beijing, they might have made even more fantastic discoveries that would have dramatically altered our view and understanding of dinosaurs, birds, and their evolution, but that event would have to wait another three-quarters of a century. The mistake of the American Museum expeditions in heading northeast contributed to a set of problems that seriously damaged dinosaur paleontology as a science between the twentieth-century world wars. Dinosaurology became rather ossified, with the extinct beasts widely portrayed as sluggish, dim-witted evolutionary dead ends doomed to extinction, an example of the “racial senescence” theory that was widely held among researchers who preferred a progressive concept of evolution at odds with more random Darwinian natural selection. It did not help matters when artist/paleontologist Gerhard Heilmann published a seminal work that concluded that birds were not close relatives of dinosaurs, in part because he thought dinosaurs lacked a wishbone furcula that had just been found, but misidentified, in Oviraptor. The advent of the Depression, followed by the trauma of World War II—which led to the loss of some important specimens on the continent as a result of Allied and Axis bombing—brought major dinosaur research to a near halt.
Even so, public interest in dinosaurs remained high. The paleoart of Charles Knight made him famous. The Star Wars– Jurassic Park of its time, RKO’s King Kong of 1933 amazed audiences with its dinosaurs seemingly brought to life. Two major film comedies, 1938’s Bringing Up Baby, starring Cary Grant and Katherine Hepburn, and 1949’s On the Town, featuring Gene Kelly and Frank Sinatra, involved climactic scenes in which sauropod skeletons at a semifictional New York museum collapsed because of the hijinks of the lead characters. Unfortunately, the very popularity of dinosaurs gave them a circus air that convinced many scientists that they were beneath their scientific dignity and attention. Despite the problems, discoveries continued. In an achievement remarkable for a nation ravaged by the Great Patriotic War and suffering under the oppression of Stalinism, the Soviets mounted postwar expeditions to Mongolia that uncovered the Asian version of Tyrannosaurus and the enigmatic arms of enormous clawed Therizinosaurus. Equally outstanding was how the Poles took the place of the Soviets in the 1960s, discovering in the process the famed complete skeleton of Velociraptor engaged in combat with Protoceratops. They too found another set of mysterious long arms with oversized claws, Deinocheirus. In the United States, Roland Bird studied the trackways of herds of Texas-sized Cretaceous sauropods before World War II. Shortly after the global conflict, the Triassic Ghost Ranch quarry in the Southwest, packed with complete skeletons of little Coelophysis, provided the first solid knowledge of the beginnings of predatory dinosaurs. Also found shortly afterward in the Southwest was the closely related but much larger crested theropod Dilophosaurus of the Early Jurassic.
What really spurred the science of dinosaur research were the Yale expeditions to Montana in the early 1960s that dug into the little-investigated Early Cretaceous Cloverly Formation. The discovery of the Velociraptor relative Deinonychus finally made it clear that some dinosaurs were sophisticated, energetic, agile dinobirds, a point reinforced by the realization that it and the other sickle claws, the troodontids, as well as the ostrichlike ornithomimids, had fairly large, complex brains. These developments led John Ostrom to note and detail the similarities between his Deinonychus and Archaeopteryx and to conclude that birds are the descendants of energetic small theropod dinosaurs. Realizing that the consensus dating back to their original discovery that dinosaurs were an expression of the reptilian pattern was flawed, Robert Bakker in the 1960s and 1970s issued a series of papers contending that dinosaurs and their feathered descendants constituted a distinct group of archosaurs whose biology and energetics were more avian than reptilian. Eventually, in the article “Dinosaur Renaissance” in a 1975 Scientific American, Bakker proposed that some small dinosaurs themselves were feathered. In the late 1970s, Montana native John Horner found baby hadrosaurs and their nests, providing the first look at how some dinosaurs reproduced. At the same time, researchers from outside paleontology stepped into the field and built up the evidence that the impact of an asteroid over six miles in diameter was the long-sought great dinosaur killer. This extremely controversial and contentious idea turned into the modern paradigm on the finding of a state-sized meteorite crater in southeastern Mexico dating to the end of the dinosaur era. These radical and controversial concepts greatly boosted popular attention on dinosaurs, culminating in the Jurassic Park novels and films that sent dinomania to unprecedented heights. The elevated public awareness was combined with digital technology in the form of touring exhibits of robotic dinosaurs. This time the interest of paleontologists was elevated as well, inspiring the second and ongoing golden age of dinosaur discovery and research, which is surpassing that which has gone before. Assisting the work are improved scientific techniques in the area of evolution and phylogenetics, including cladistic genealogical analysis, which has improved the investigation of dinosaur relationships. A new generation of artists has portrayed dinosaurs with a “new look” that lifts tails in the air and gets feet off the ground to represent the more dynamic gaits that are in line with the more active lifestyles the researchers now favor. I noticed that the sickle-clawed dromaeosaurs and troodonts, as well as the oviraptorosaurs, possessed anatomical features otherwise found in flightless birds and suggested that these dinosaurs were also secondarily flightless.
Dinosaurs are being found and named at an unprecedented rate as dinosaur science goes global, with efforts under way on all continents. In the 1970s the annual Society of Vertebrate Paleontology meeting might have seen a half-dozen presentations on dinosaurs; now it is in the area of a couple of hundred. Especially important has been the development of local expertise made possible by the rising economies of many secondworld nations, reducing the need to import Western expertise.
In South America, Argentine and American paleontologists collaborated in the 1960s and 1970s to reveal the first Middle and Late Triassic protodinosaurs, finally showing that the very beginnings of dinosaurs started among surprisingly small archosaurs. Since then, Argentina has been the source of endless remains from the Triassic to the end of the Cretaceous that include the early theropods Eoraptor and Herrerasaurus, supertitanosaur sauropods such as Argentinosaurus, Futalongnkosaurus, and Dreadnoughtus, and the oversized theropods such as Giganotosaurus that preyed on them. Among the most extraordinary finds have been sauropod nesting grounds that allow us to see how the greatest land animals of Earth’s history reproduced themselves. In southern Africa excellent remains of an Early Jurassic species of Coelophysis verified how uniform the dinosaur fauna was when all continents were gathered into Pangaea. Northern Africa has been the major center of activity as a host of sauropods and theropods have filled in major gaps in dinosaur history. Australia is geologically the most stable of continents, with relatively little in the way of tectonically driven erosion to either bury fossils or later expose them, so dinosaur finds have been comparatively scarce despite the aridity of the continent. The most important discoveries have been of Cretaceous dinosaurs that lived close to the South Pole, showing the climatic extremes dinosaurs were able to adapt to. Glacier-covered Antarctica is even less suitable prospecting territory, but even it has produced the Early Jurassic crested avepod Cryolophosaurus as well as other dinosaur bones.
At the opposite end of the planet, the uncovering of a rich Late Cretaceous fauna on the Alaskan North Slope confirms the ability of dinosaurs to dwell in latitudes cold and dark enough in the winter that lizards and crocodilians are not found in the same deposits. Farther south, a cadre of researchers have continued to plumb the great dinosaur deposits of western North America as they build the most detailed sample of dinosaur evolution from the Triassic until their final loss. We now know that armored ankylosaurs were roaming along with plated stegosaurs in the Morrison Formation, a collection of sauropods has been exposed from the Early Cretaceous, and one new ceratopsian and hadrosaur after another is coming to light in the classic Late Cretaceous beds.
Now Mongolia and especially China have become the great frontier in dinosaur paleontology. Even during the chaos of the Cultural Revolution, Chinese paleontologists made major discoveries, including the first spectacularly long-necked mamenchisaur sauropods. As China modernized and Mongolia gained independence, Canadian and American researchers have worked with their increasingly skilled resident scientists, who have become a leading force in dinosaur research. It was finally realized that the oviraptors found associated with nests at the Flaming Cliffs were not eating the eggs but brooding them in a pre-avian manner. Almost all of China is productive when it comes to dinosaurs, and after many decades paleontologists started paying attention to the extraordinary fossils being dug up by local farmers from Early Cretaceous lake beds in the northeast of the nation.
In the mid-1990s, complete specimens of small compsognathid theropods labeled Sinosauropteryx began to show up with their bodies covered with dense coats of bristly protofeathers. More recently it has been argued that it is often possible to determine the color of the feathers! This was just the start: the Yixian beds are so extensive and productive that they have become an inexhaustible source of beautifully preserved material as well as of strife, as the locals contend with the authorities for the privilege of excavating the fossils for profit—sometimes altering the remains to “improve” them—rather than for rigorous science. The feathered dinosaurs soon included the potential oviraptorosaur Caudipteryx. Even more astonishing have been the Yixian dromaeosaurs. These small sickle claws bear fully developed wings not only on their arms but on their similarly long legs as well. This indicates not only that dromaeosaurs first evolved as fliers but that they were adapted to fly in a manner quite different from the avian norm. The therizinosaur Beipiaosaurus looks like a refugee from a Warner Brothers cartoon. But the Yixian is not just about confirming that birds are dinosaurs and that some dinosaurs were feathered. One of the most common dinosaurs of the Early Cretaceous is the parrotbeaked Psittacosaurus. Although it was known from numerous skeletons across Asia found over the last eighty years, no one had a clue that its tail sported large, arcing, bristly spines until a complete individual with preserved skin was found in the Yixian. To top things off, the Yixian has produced the small ornithischian Tianyulong, which suggests that insulating fibers were widespread among small dinosaurs. There are new museums in China packed with enormous numbers of undescribed dinosaur skeletons on display and in storage.
On a global scale, the number of dinosaur trackways that have been discovered is in the many millions. This is logical in that a given dinosaur could potentially contribute only one skeleton to the fossil record but could make innumerable footprints. In a number of locations, trackways are so abundant that they form what have been called “dinosaur freeways.” Many of the trackways were formed in a manner that suggests their makers were moving in herds, flocks, packs, and pods. A few may record the attacks of predatory theropods on herbivorous dinosaurs.
The history of dinosaur research is not just one of new ideas and new locations; it is also one of new techniques and technologies. The turn of the twenty-first century has seen paleontology go high tech with the use of computers for processing data and high-resolution CT scanners to peer inside fossils without damaging them. Dinosaurology has also gone microscopic and molecular in order to assess the lives of dinosaurs at a more intimate level, telling us how fast they grew, how long they lived, and at what age they started to reproduce. Bone isotopes are being used to help determine dinosaur diets and to state that some dinosaurs were semiaquatic. And it turns out that feather pigments can be preserved well enough to restore original colors. Meanwhile the Jurassic World franchise helps sustain popular interest in the group even as it presents an obsolete, prefeather image of the birds’ closest relations.
The evolution of human understanding of dinosaurs has undergone a series of dramatic transformations since they were scientifically discovered almost two hundred years ago. This is true because dinosaurs are a group of “exotic” animals whose biology was not obvious from the start, unlike fossil mammals or lizards. It has taken time to build up the knowledge base needed to resolve their true form and nature. The latest revolution is still young. When I was a youth, I learned that dinosaurs were, in general, sluggish, cold-blooded, tail-dragging, slow-growing, dim-witted reptiles that did not care for their young. The idea that some were feathered and that birds are living descendants was beyond imagining. Dinosaur paleontology has matured in that it is unlikely that a reorganization of similar scale will occur in the future, but we now know enough
about the inhabitants of the Mesozoic to have the basics well established. Sauropods will not return to a hippo-like lifestyle, and dinosaurs’ tails will not be chronically plowing through Mesozoic muds. Dinosaurs are no longer so mysterious. Even so, the research is nowhere near its end. To date, over seven hundred valid dinosaur species in about five hundred genera have been discovered and named. This probably represents at most a quarter, and perhaps a much smaller fraction, of the species that have been preserved in sediments that can be accessed. And, as astonishingly strange as many of the dinosaurs uncovered so far have been, there are equally odd species waiting to be unearthed. Reams of work based on as-yet-undeveloped technologies and techniques will be required to provide further details about both dinosaur biology and the world in which they lived. And although a radical new view is improbable, there will be many surprises.
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