The dinosaur renaissance[1] was a highly specified scientific revolution that began in the late 1960s and led to renewed academic and popular interest in dinosaurs. It was initially spurred on by research indicating that dinosaurs may have been active warm-blooded animals, rather than sluggish cold-blooded lizard-like reptilians as had been the prevailing view and description during the first half of the twentieth century.
This new view of dinosaurs was championed particularly by John Ostrom, who argued that birds evolved from coelurosaurian dinosaurs,[2] and Robert Bakker, who argued that dinosaurs were warm-blooded in a way similar to modern mammals and birds.[3] Bakker frequently portrayed his ideas as a "renaissance" akin to those in the late nineteenth century, referring to the period in between the Dinosaur Wars and the dinosaur renaissance as "the dinosaur doldrums".[3]
In the mid and latter parts of the nineteenth century, some scientists thought there was a close relationship between birds and dinosaurs—and that dinosaurs represented an intermediate stage between "reptiles" and birds.
The similarity of the hands of Deinonychus (left) and Archaeopteryx (right) led John Ostrom to revive the link between non-avian dinosaurs and avian dinosaurs, birds.
Shortly after the 1859 publication of Charles Darwin's The Origin of Species, British biologist and evolution-defender Thomas Henry Huxley proposed that birds were descendants of dinosaurs. He cited skeletal similarities, particularly among dinosaurs, the "first bird"—Archaeopteryx—and modern birds.[4][5] However, in 1926, Gerhard Heilmann wrote his influential book The Origin of Birds,[6] in which he dismissed the dinosaur–bird link, based on the dinosaurs' supposed lack of a furcula.[7] Thereafter, the accepted hypothesis was that birds evolved from crocodylomorph and thecodont ancestors, rather than from dinosaurs. This removed dinosaurs from a central role in debates about the origin of living species, and may have contributed to the decline of academic interest in dinosaur evolution.[citation needed]
This situation persisted until 1964, when John Ostrom discovered a small carnivorous dinosaur which he named Deinonychus antirrhopus,[8] a theropod whose skeletal resemblance to birds seemed unmistakable. This led Ostrom to argue that Huxley had been right, and that birds had indeed evolved from dinosaurs.[2] Although it was Deinonychus that inspired Ostrom to connect birds with dinosaurs, very similar birdlike dinosaurs, such as Velociraptor, had been known for many decades,[9] but no connection had been made. After Ostrom's discoveries, the idea that birds are dinosaurs gained support among palaeontologists, and today it is almost universally accepted.[10]
Dinosaur monophyly
Around 1880, dinosaurs were largely treated as a monophyletic group (i.e. having a last common ancestor not shared with other reptiles). However, Harry Seeley disagreed with this interpretation, and split the Dinosauria into two orders, the Saurischia ("lizard-hipped") and the Ornithischia ("bird-hipped"), which were seen as members of the Archosauria with no special relationship to each other.[11][12] As such, the Dinosauria was no longer seen as a scientific grouping, and "dinosaur" was reduced to being a popular term, without scientific meaning. This became the standard interpretation throughout much of the twentieth century.[13]
This changed in 1974, when Bakker and Peter Galton published a paper in Nature, arguing that not only were dinosaurs a natural monophyletic group, but that they should be raised to the status of a new class, which would also contain birds.[14] Although initially this revival of dinosaur monophyly was controversial,[15] the idea did gain acceptance, and since the rise of cladistic methodology, it has been nearly universally supported.[16]
Warm-bloodedness and activity levels
An 1897 painting of "Laelaps" (now Dryptosaurus) by Charles R. Knight. Bakker pointed to such restorations to demonstrate that in the 19th century it was widely accepted that dinosaurs may have been active and agile animals.
In a series of scientific papers, books, and popular articles in the 1970s and 1980s, beginning with his 1968 paper "The superiority of dinosaurs",[17] Robert Bakker argued strenuously that dinosaurs were warm-blooded and active animals, capable of sustained periods of high activity. In most of his writings Bakker framed his arguments as new evidence leading to a revival of ideas popular in the late 19th century, frequently referring to an ongoing "dinosaur renaissance". He used a variety of anatomical and statistical arguments to defend his case,[18][19] the methodology of which was fiercely debated among scientists.[20]
These debates sparked interest in new methods for ascertaining the palaeobiology of extinct animals, such as bone histology, which have been successfully applied to determining the growth-rates of many dinosaurs. Today, it is generally thought that many or perhaps all dinosaurs had higher metabolic rates than living reptiles, but also that the situation is more complex and varied than Bakker originally proposed. For example, while smaller dinosaurs may have been true endotherms, the larger forms could have been inertial homeotherms,[21][22] or many dinosaurs could have had intermediate metabolic rates.[23]
New theories on dinosaur behaviour
The late 1960s also saw several new theories on the way dinosaurs behaved, often involving sophisticated social behaviour. On the basis of trackways, Bakker argued that sauropod dinosaurs moved in structured herds, with the adults surrounding the juveniles in a protective ring.[17] However, shortly afterwards this particular interpretation was challenged by Ostrom[24] among others, although the venerable dinosaur track expert Roland T. Bird apparently agreed with Bakker.[25]
The first rigorous study of dinosaur nesting behaviour came in the late 1970s, when palaeontologist Jack Horner showed that the duckbilled dinosaur Maiasaura cared for its young.[26]
Changing portrayal of dinosaurs
The dinosaur renaissance changed not only scientific ideas about dinosaurs, but also their portrayal by artists. Bakker, himself a talented artist, often illustrated his ideas in a lively fashion. Indeed, Bakker's illustration of Deinonychus, made for Ostrom's 1969 description, has become one of the most recognisable and iconic of dinosaur restorations.[27]
During the 1970s, restorations of dinosaurs shifted from being lizard-like, to being more mammal- and bird-like. Artists started to show dinosaurs in more active poses, and incorporating newer theories of dinosaur locomotion and behaviour. Tails that were widely shown as having been dragged behind a creature, were now shown uplifted, in order to balance the huge bodies while active.[citation needed]
Gregory Paul in particular defended and expanded on Bakker's ideas on dinosaur anatomy. He expounded a rigorous and detailed approach to dinosaur restoration, in which he often criticised the errors of the traditionalist approach.[28] He also produced a large number of restorations showing small dinosaurs with feathers, and defended the idea in a number of articles and his book Predatory Dinosaurs of the World.[29] His view was proven largely correct in the late 1990s with the discovery of several feathered dinosaurs. Paul's ideas and style have had a significant impact on dinosaur art.[30]
Traditionally paleontology had followed geology in preferring uniformitarian mechanisms, despite the promotion by Eugene Merle Shoemaker of the importance of catastrophic impacts. During the renaissance period Walter Alvarez and others found iridium in the Cretaceous–Tertiary boundary layer. Also the Chicxulub Crater, was identified and determined to be due to a meteor impact. These discoveries led to the acceptance and popularisation of the idea that the extinction had been caused by an impact event. This in turn undermined the assumption that dinosaurs had become extinct because they were inferior to mammals. Instead it suggested they had fallen prey to a random event which no large animal could have survived.
Bakker's non-technical articles and books, particularly The Dinosaur Heresies, have contributed significantly to the popularization of dinosaur science.[31]
The 1993 film version of Jurassic Park was perhaps the most significant event in raising public awareness of dinosaur renaissance theories. For the first time in a major film, dinosaurs were portrayed as intelligent, agile, warm-blooded animals, rather than lumbering monsters more common to older films. Jack Horner was a consultant, and the artwork of Gregory Paul, Mark Hallett, Doug Henderson, and John Gurche were used in pre-production.[32] While the dinosaurs eventually shown in the films had various anatomical inaccuracies, all four of these artists are in the on-screen credits as "Dinosaur Specialists". Bakker himself was not consulted or credited, but his research is referenced by one of the characters in the film, and a Bakker look-alike appears in the sequel The Lost World.[citation needed]
↑ The term has entered into common usage after an article of the same name by paleontologist Robert T. Bakker in Scientific American, in April 1975. Examples can be found hereArchived 2007-09-27 at the Wayback Machine and here.
↑ Charig, A. (1976). "Dinosaur monophyly and a new class of vertebrates: a critical review.". In Bellairs, AA; Cox, B (eds.). Morphology and Biology of Reptiles. Linnean Society Symposium. Vol.3. pp.65–104. ISBN0-12-085850-9.
↑ Paladino, Frank V.; O'Connor, Michael P.; Spotila, James R. (1990). "Metabolism of leatherback turtles, gigantothermy, and thermoregulation of dinosaurs". Nature. 344 (6269): 858–860. Bibcode:1990Natur.344..858P. doi:10.1038/344858a0. S2CID4321764.
↑ Barrick, R. E.; Showers, W. J.; Fischer, A. G. (1996). "Comparison of Thermoregulation of Four Ornithischian Dinosaurs and a Varanid Lizard from the Cretaceous Two Medicine Formation: Evidence from Oxygen Isotopes". PALAIOS. 11 (4): 295–305. Bibcode:1996Palai..11..295B. doi:10.2307/3515240. JSTOR3515240.
↑ Darren Naish, 2021, "Deinonychus", in Dinopedia - A Brief Compendium of Dinosaur Lore, Princeton University Press
↑ Paul, G. S. (1987). "The science and Art of Restoring the Life Appearance of Dinosaurs and Their Relatives; a Rigorous How-to Guide". In Czerkas, S. J.; Olson, E. C. (eds.). Dinosaurs Past and Present, vol. II. University of Washington Press. ISBN0-295-96570-3.
Velociraptor is a genus of small dromaeosaurid dinosaurs that lived in Asia during the Late Cretaceous epoch, about 75 million to 71 million years ago. Two species are currently recognized, although others have been assigned in the past. The type species is V. mongoliensis, named and described in 1924. Fossils of this species have been discovered in the Djadochta Formation, Mongolia. A second species, V. osmolskae, was named in 2008 for skull material from the Bayan Mandahu Formation, China.
Deinonychus is a genus of dromaeosaurid theropod dinosaur with one described species, Deinonychus antirrhopus. This species, which could grow up to 3.4 meters (11 ft) long, lived during the early Cretaceous Period, about 115–108 million years ago. Fossils have been recovered from the U.S. states of Montana, Utah, Wyoming, and Oklahoma, in rocks of the Cloverly Formation and Antlers Formation, though teeth that may belong to Deinonychus have been found much farther east in Maryland.
Archosauria is a clade of diapsid sauropsid tetrapods, with birds and crocodilians being the only living representatives. Archosaurs are broadly classified as reptiles, in the cladistic sense of the term, which includes birds. Extinct archosaurs include non-avian dinosaurs, pterosaurs and extinct relatives of crocodilians. Modern paleontologists define Archosauria as a crown group that includes the most recent common ancestor of living birds and crocodilians, and all of its descendants. The base of Archosauria splits into two clades: Pseudosuchia, which includes crocodilians and their extinct relatives; and Avemetatarsalia, which includes birds and their extinct relatives.
Compsognathus is a genus of small, bipedal, carnivorous theropod dinosaur. Members of its single species Compsognathus longipes could grow to around the size of a chicken. They lived about 150 million years ago, during the Tithonian age of the late Jurassic period, in what is now Europe. Paleontologists have found two well-preserved fossils, one in Germany in the 1850s and the second in France more than a century later. Today, C. longipes is the only recognized species, although the larger specimen discovered in France in the 1970s was once thought to belong to a separate species and named C. corallestris.
Dromaeosauridae is a family of feathered coelurosaurian theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek δρομαῖος (dromaîos), meaning 'running at full speed', 'swift', and σαῦρος (saûros), meaning 'lizard'. In informal usage, they are often called raptors, a term popularized by the film Jurassic Park; several genera include the term "raptor" directly in their name, and popular culture has come to emphasize their bird-like appearance and speculated bird-like behavior.
Robert Thomas Bakker is an American paleontologist who helped reshape modern theories about dinosaurs, particularly by adding support to the theory that some dinosaurs were endothermic (warm-blooded). Along with his mentor John Ostrom, Bakker was responsible for initiating the ongoing "dinosaur renaissance" in paleontological studies, beginning with Bakker's article "Dinosaur Renaissance" in the April 1975 issue of Scientific American. His specialty is the ecological context and behavior of dinosaurs.
Sinornithosaurus is a genus of feathered dromaeosaurid dinosaur from the early Cretaceous Period of the Yixian Formation in what is now China. It was the fifth non–avian feathered dinosaur genus discovered by 1999. The original specimen was collected from the Sihetun locality of western Liaoning. It was found in the Jianshangou beds of the Yixian Formation, dated to 124.5 million years ago. Additional specimens have been found in the younger Dawangzhangzi bed, dating to around 122 million years ago.
John Harold Ostrom was an American paleontologist who revolutionized the modern understanding of dinosaurs. Ostrom's work inspired what his pupil Robert T. Bakker has termed a "dinosaur renaissance".
Coelurus is a genus of coelurosaurian dinosaur from the Late Jurassic period. The name means "hollow tail", referring to its hollow tail vertebrae. Although its name is linked to one of the main divisions of theropods (Coelurosauria), it has historically been poorly understood, and sometimes confused with its better-known contemporary Ornitholestes. Like many dinosaurs studied in the early years of paleontology, it has had a confusing taxonomic history, with several species being named and later transferred to other genera or abandoned. Only one species is currently recognized as valid: the type species, C. fragilis, described by Othniel Charles Marsh in 1879. It is known from one partial skeleton found in the Morrison Formation of Wyoming, United States. It was a small bipedal carnivore with elongate legs.
Darren William Naish is a British vertebrate palaeontologist, author and science communicator.
Tenontosaurus is a genus of medium- to large-sized ornithopod dinosaur. It was a relatively medium sized ornithopod, reaching 6.5 to 8 meters in length and 600 to 1,000 kilograms in body mass. It had an unusually long, broad tail, which like its back was stiffened with a network of bony tendons.
The physiology of dinosaurs has historically been a controversial subject, particularly their thermoregulation. Recently, many new lines of evidence have been brought to bear on dinosaur physiology generally, including not only metabolic systems and thermoregulation, but on respiratory and cardiovascular systems as well.
Cultural depictions of dinosaurs have been numerous since the word dinosaur was coined in 1842. The non-avian dinosaurs featured in books, films, television programs, artwork, and other media have been used for both education and entertainment. The depictions range from the realistic, as in the television documentaries from the 1990s into the first decades of the 21st century, or the fantastic, as in the monster movies of the 1950s and 1960s.
The scientific question of within which larger group of animals birds evolved has traditionally been called the "origin of birds". The present scientific consensus is that birds are a group of maniraptoran theropod dinosaurs that originated during the Mesozoic Era.
The Dinosaur Heresies: New Theories Unlocking the Mystery of the Dinosaurs and Their Extinction is a 1986 book written by Robert T. Bakker.
Paleoart is any original artistic work that attempts to depict prehistoric life according to scientific evidence. Works of paleoart may be representations of fossil remains or imagined depictions of the living creatures and their ecosystems. While paleoart is typically defined as being scientifically informed, it is often the basis of depictions of prehistoric animals in popular culture, which in turn influences public perception of and fuels interest in these animals. The word paleoart is also used in an informal sense, as a name for prehistoric art, most often cave paintings.
Phytodinosauria is a group of dinosaurs proposed in 1986, combining the Sauropodomorpha and Ornithischia as sister groups, conceptualized as a superorder of herbivorous dinosaurs excluding the carnivorous Theropoda. This hypothesis has been refuted by modern cladistic analysis, showing such a group to be polyphyletic. Modern studies either combine the Theropoda and Sauropodormorpha in the Saurischia or the Theropoda and Ornithischia in the Ornithoscelida.
All Yesterdays: Unique and Speculative Views of Dinosaurs and Other Prehistoric Animals is a 2012 art book on the palaeoartistic reconstruction of dinosaurs and other extinct animals by John Conway, C. M. Kosemen and Darren Naish. A central tenet of the book concerns the fact that many dinosaur reconstructions are outdated, overly conservative, and inconsistent with the variation observed in modern animals. This focus is communicated through an exploration of views of dinosaurs and related animals that are unusual and sometimes even confusing to viewers, but which are well within the bounds of behaviour, anatomy and soft tissue that we see in living animals.
The Origin of Birds is an early synopsis of bird evolution written in 1926 by Gerhard Heilmann, a Danish artist and amateur zoologist. The book was born from a series of articles published between 1913 and 1916 in Danish, and although republished as a book it received mainly criticism from established scientists and got little attention within Denmark. The English edition of 1926, however, became highly influential at the time due to the breadth of evidence synthesized as well as the artwork used to support its arguments. It was considered the last word on the subject of bird evolution for several decades after its publication.
This timeline of dromaeosaurid research is a chronological listing of events in the history of paleontology focused on the dromaeosaurids, a group of sickle-clawed, bird-like theropod dinosaurs including animals like Velociraptor. Since the Native Americans of Montana used the sediments of the Cloverly Formation to produce pigments, they may have encountered remains of the dromaeosaurid Deinonychus hundreds of years before these fossils came to the attention of formally trained scientists.
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