Dinosaur Studies

Observant readers may have noticed that one continent, Australia, has barely been mentioned, and Antarctica completely neglected. This lack of information is because Australia has become a discovery site for abundant dinosaur fossils (especially tracks) only in the past 35 years, and the first discovery of an Antarctic dinosaur was not until 1986. However, both of these continents will undoubtedly see expanded research as these finds inspire increased exploration.

Discussion of the people in dinosaur studies during the latter half of the twentieth century must be limited for several reasons. One reason is that the author of this book does not feel qualified to judge which of these people (many of whom are still active in the discipline, and perhaps reading this) deserve mention as important contributors to the long-term history of dinosaur studies. Such a pronouncement will be much easier to make in another 50 years or so, when the enduring contributions made by these investigators will be more evident. Of course, some genuinely notable discoveries already happened in the latter half of the twentieth century and beginning of the twenty-first, and those discoveries and the people associated with them will be mentioned where appropriate. Time will tell whether these contributions will make paleonto-logical history. With that said, three paleontologists in the latter half of the twentieth century, Edwin H. Colbert, John Ostrom, and José F. Bonaparte, stand out for providing the most long-lasting scientific contributions from which all modern investigators in dinosaur studies will benefit.

Edwin H. Colbert (1905-2001) is best known in dinosaur paleontology for his discovery, in 1947, of a site that contained hundreds of the Late Triassic theropod Coelophysis bauri (Chapter 11). The site, in the Chinle Formation at Ghost Ranch, New Mexico, was located near the summer home of famed painter Georgia O'Keeffe (1887-1986), who occasionally stopped by the excavation to talk with Colbert. Late Triassic dinosaurs have always held a special interest to paleontologists, because they represent the earliest dinosaurs (Chapter 6). Thus for Colbert to document such a rich find was a major contribution to our understanding of the origin of dinosaurs and a source of detailed paleontological information about them. For example, because

The preceding history itrarily cuts off at about 1950 and is thus incomplete, but it provides a summary of dinosaur studies up to that point.

of their abundance, growth series and population structures for this theropod could be proposed. This is an unusual situation for any dinosaur species because of the rarity of multiple specimens of the same species. Additionally, cannibalism was first interpreted for this species based on the specimens from Ghost Ranch, where juvenile bones were thought to be inside the body cavities of an adult. This has been re-interpreted, however, because the bones of one were actually just on top of another, rather than inside of it (Chapter 9). Furthermore, the unusual occurrence of so many individuals of a single species of carnivorous dinosaur, similar to the findings in the Cleveland-Lloyd Quarry, led to some debated hypotheses regarding the pre-burial history of the assemblage, as well as implied social behavior (Chapter 6). Colbert was also well known for his excellent textbooks on vertebrate paleontology and popular books on dinosaurs, which have helped to educate aspiring vertebrate paleontologists worldwide. His fascinating works on the history of dinosaur studies also gave science enthusiasts a sense of the uniqueness of using fieldwork to search for the remains of long-dead animals. Colbert's historical works were a major source of information for this chapter, and they certainly set the standard for all future bibliographers of dinosaur paleontologists.

John Ostrom (1928-2005) is credited with sparking the Dinosaur Renaissance of the past 30 years by his detailed examination and consequent hypotheses of the Early Cretaceous theropod Deinonychus (Chapter 9), which he first reported in 1969. Ostrom, through convincing use of his data on Deinonychus, revived the idea (first proposed by Huxley and unintentionally augmented by the work of Hitchcock in the nineteenth century) that some dinosaurs were more active and bird-like in their behavior, rather than reptilian. Ostrom's interpretation was based on functional morphology, the study of how the form of an animal relates to its functions, an approach that had been used before in dinosaur studies but rarely so effectively. New interest thus began in studying the extent of this bird-like behavior in some dinosaurs, namely whether it was reflected by physiological indicators of endo-thermy (Chapter 8) or was related to evolutionary links between dinosaurs and modern birds (Chapter 15). Ostrom also made a very important discovery while examining a skeleton in a small Dutch museum. Ostrom recognized the skeleton, identified initially as a pterosaur (flying reptile), as a previously unknown specimen of Archaeopteryx, one of only seven ever described.

Dinosaurs from Europe and North America were studied the most during the nineteenth century and interest expanded to Africa and Asia in the first half of the twentieth century. But research in South America in the latter half of the twentieth century was prompted largely by the efforts of José F. Bonaparte. Of all living paleontologists, Bonaparte has named or co-named the largest number of dinosaur genera (10 as of the writing of this book), including Argentinosaurus (a huge sauropod; Chapter 10), Carnotaurus (a large, horned theropod; Chapter 9), and Abelisaurus, the latter a representative of a group of Cretaceous theropods unique to South America. His discoveries, primarily in his native Argentina, have shown important evolutionary relationships between dinosaurs of separate continents, especially the "southern continents" of South America, Africa, India, Australia, and Antarctica, which formed one landmass in southern latitudes, called Gondwana, during much of the Jurassic (Chapters 4 and 6). Bonaparte is the former student of influential American vertebrate paleontologist Alfred Sherwood Romer (1894-1973), and is continuing his tradition of excellence.

Other notable dinosaur paleontologists, who have already encouraged much interest in dinosaurs in the USA and abroad, include Americans Robert T. Bakker, John (Jack) R. Horner, and Paul C. Sereno, as well as Martin G. Lockley, originally from Wales but now based in the USA. Bakker, a former student of Ostrom, is best known for his role as a publicly visible cheerleader for alternative views of dinosaurs as active animals more akin to birds and mammals, as opposed to their previous stereotype as sluggish reptilians. He is also one of the best popularizers of contentious ideas about dinosaurs that have provoked much discussion and attempts at refutation; his main theses are summarized in his 1986 book The Dinosaur

Heresies. Jack Horner, along with his now deceased friend Bob Makela, began his career as an amateur paleontologist and discovered dinosaur-nesting horizons of the Late Cretaceous ornithopod Maiasaura, the first dinosaur nests found in North 3

America (Chapters 8 and 11). This work and further investigations changed the conception of dinosaurs from solitary and uncaring creatures to social, nurturing animals. In a relatively short time, Sereno and his research teams have chalked up a remarkable number of noteworthy dinosaur discoveries in remote areas of

Argentina, Morocco, Niger, and Inner Mongolia. Included in his scientifically important contributions are the discovery and description of what are possibly the oldest known dinosaurs or dinosaur ancestors (Chapter 6), and he has otherwise made significant advances in the cladistic classification of dinosaurs. Lockley is the most recognized dinosaur ichnologist in the world, having studied and written about dinosaur tracks and their scientific pertinence in numerous peer-reviewed journal articles and books intended for public consumption. Although most of his work has been in the track-rich Mesozoic strata of the western United States, he has also studied dinosaur tracks from Argentina, Bolivia, Brazil, Portugal, Spain, central Asia,

China, and Korea, thus considerably augmenting the skeletal record for dinosaurs formerly missing from many of these regions. Lockley and the other aforementioned paleontologists are especially well known for their educational outreach efforts, whether through books written for interested lay people or lectures given in public forums.

Of course, modern dinosaur paleontologists are members of an increasingly global science. A short list, for purely practical reasons of limited space, might include Phillip J. Currie of Canada, Dong Zhi-Ming of China, Altangerel Perle of Mongolia, Patricia Vickers-Rich, Thomas Rich, and Tony Thulborn of Australia, Konstantin Mikhailov of Russia, Anusuya Chinsamy-Turan of South Africa, Fernando Novas and Rudolfo Coria of Argentina, and Armand de Ricqles of France. Further internationalization of dinosaur studies and inclusion of more participants from less industrialized nations should continue as Internet communications become accessible in more places and bureaucratic obstacles lessen. Stricter immigration control in the USA since 2001, however, has significantly decreased the number of foreign-born graduate students and scientists entering the USA, which may adversely affect future cooperation. Likewise, large-scale warfare in the Middle East since 2003 has hampered the participation of USA scientists in projects taking place in countries opposed to US-led war efforts.

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