Assessing Social Behaviour, Ontogenetic Change and Taxonomic Status in a Juvenile Gorgosaurus Libratus (Dinosauria; Theropoda; Tyrannosauridae) PDF Download
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Author: Gavin Bradley Publisher: ISBN: Category : Albertosaurus Languages : en Pages : 208
Book Description
The sparseness of the fossil record and the subjectivity of interpreting behaviour from morphological and taphonomic evidence have impeded studies on the behaviour of juvenile theropod dinosaurs. Most evidence for social behaviour in juvenile dinosaurs comes from multi individual bone beds or parent dinosaurs preserved while brooding on eggs or young. There is therefore a desire for alternative methods of assessing social behaviour, leading to the two key questions of this thesis: 1) can inferences about social behaviour be made using isolated specimens?, and 2) does gregariousness change with ontogeny in Gorgosaurus? A multidisciplinary study using isolated specimens of Gorgosaurus libratus, including a newly described juvenile specimen from Dinosaur Provincial Park in southern Alberta, was carried out in the hopes of answering these two questions. A review of social behaviour in modern animals suggests that gregariousness is gradational and varies from taxon to taxon, even within closely related groups such as Felidae. Inferences of social behaviour for dinosaurs based solely on phylogenetic bracketing is therefore not recommended. However, numerous analyses can be performed on isolated specimens in order to infer social behaviours including parental care, group living, sexual display and combat. For example, palaeopathologies may indicate intraspecific combat. Ontogenetic changes, such as growth curves, allometry of horns and crests, and changes in stable isotopes because of dietary changes may also indicate changing behavioural as well as ecological roles during development. Femoral circumferences are useful in inferring body mass of theropods, and in bone bed aggregations this can aid in studies of growth rates, which can inform social behaviour. Taphonomic damage can reduce sample sizes and make such studies problematic. Statistical analyses, however, suggest that three femoral-diameter-based estimation models may be used to predict femoral circumference measurements in tyrannosaurids. Ontogenetic morphological changes in Gorgosaurus may also inform inferences about social behaviour. Positive allometric growth of the lacrimal horns may imply a display function, as seen in modern bovid and cervid mammals. Slow maximum growth rates of juvenile Gorgosaurus, compared to other tyrannosaurids, calculated using lines of arrested growth and body mass estimations, may indicate social aggregation during early ontogeny in order to survive alongside faster growing and larger predators, such as Daspletosaurus or, alternatively, reduced growth due to nutritional stresses on juveniles. Macrowear patterns in the teeth of UALVP 49500 and UALVP 10, an adult specimen, exhibit four major types of tooth wear: enamel spalling, longitudinal facets, tip wear, and barrel-shaped puncture marks. Adult teeth were typified by tip wear, and juvenile teeth were typified by longitudinal wear facets. This is hypothesised to reflect a change in feeding behaviour during ontogeny, from shearing and slicing of meat, with high levels of tooth occlusion in the young, to the "puncture and pull" method previously hypothesized for adults. A slicing feeding method for juveniles is further supported by thinner teeth with higher denticle densities, smaller bite forces, and a more circular orbit shape that is less resistant to the strain of high bite forces on the skull. This multidisciplinary analysis shows that substantial ontogenetic change occurred in Gorgosaurus, and demonstrates that social behaviour may be inferred from isolated specimens. As well, a description of a juvenile Gorgosaurus libratus, UALVP 49500, presents the first examination of post cranial material in such a specimen, and supports a genus-level distinction between Albertosaurus sarcophagus and Gorgosaurus libratus.
Author: Gavin Bradley Publisher: ISBN: Category : Albertosaurus Languages : en Pages : 208
Book Description
The sparseness of the fossil record and the subjectivity of interpreting behaviour from morphological and taphonomic evidence have impeded studies on the behaviour of juvenile theropod dinosaurs. Most evidence for social behaviour in juvenile dinosaurs comes from multi individual bone beds or parent dinosaurs preserved while brooding on eggs or young. There is therefore a desire for alternative methods of assessing social behaviour, leading to the two key questions of this thesis: 1) can inferences about social behaviour be made using isolated specimens?, and 2) does gregariousness change with ontogeny in Gorgosaurus? A multidisciplinary study using isolated specimens of Gorgosaurus libratus, including a newly described juvenile specimen from Dinosaur Provincial Park in southern Alberta, was carried out in the hopes of answering these two questions. A review of social behaviour in modern animals suggests that gregariousness is gradational and varies from taxon to taxon, even within closely related groups such as Felidae. Inferences of social behaviour for dinosaurs based solely on phylogenetic bracketing is therefore not recommended. However, numerous analyses can be performed on isolated specimens in order to infer social behaviours including parental care, group living, sexual display and combat. For example, palaeopathologies may indicate intraspecific combat. Ontogenetic changes, such as growth curves, allometry of horns and crests, and changes in stable isotopes because of dietary changes may also indicate changing behavioural as well as ecological roles during development. Femoral circumferences are useful in inferring body mass of theropods, and in bone bed aggregations this can aid in studies of growth rates, which can inform social behaviour. Taphonomic damage can reduce sample sizes and make such studies problematic. Statistical analyses, however, suggest that three femoral-diameter-based estimation models may be used to predict femoral circumference measurements in tyrannosaurids. Ontogenetic morphological changes in Gorgosaurus may also inform inferences about social behaviour. Positive allometric growth of the lacrimal horns may imply a display function, as seen in modern bovid and cervid mammals. Slow maximum growth rates of juvenile Gorgosaurus, compared to other tyrannosaurids, calculated using lines of arrested growth and body mass estimations, may indicate social aggregation during early ontogeny in order to survive alongside faster growing and larger predators, such as Daspletosaurus or, alternatively, reduced growth due to nutritional stresses on juveniles. Macrowear patterns in the teeth of UALVP 49500 and UALVP 10, an adult specimen, exhibit four major types of tooth wear: enamel spalling, longitudinal facets, tip wear, and barrel-shaped puncture marks. Adult teeth were typified by tip wear, and juvenile teeth were typified by longitudinal wear facets. This is hypothesised to reflect a change in feeding behaviour during ontogeny, from shearing and slicing of meat, with high levels of tooth occlusion in the young, to the "puncture and pull" method previously hypothesized for adults. A slicing feeding method for juveniles is further supported by thinner teeth with higher denticle densities, smaller bite forces, and a more circular orbit shape that is less resistant to the strain of high bite forces on the skull. This multidisciplinary analysis shows that substantial ontogenetic change occurred in Gorgosaurus, and demonstrates that social behaviour may be inferred from isolated specimens. As well, a description of a juvenile Gorgosaurus libratus, UALVP 49500, presents the first examination of post cranial material in such a specimen, and supports a genus-level distinction between Albertosaurus sarcophagus and Gorgosaurus libratus.
Author: J. Michael Parrish Publisher: Indiana University Press ISBN: 0253009472 Category : Science Languages : en Pages : 313
Book Description
Drawn from a 2005 international symposium, these essays explore current tyrannosaurid current research and discoveries regarding Tyrannosaurus rex. The opening of an exhibit focused on “Jane,” a beautifully preserved tyrannosaur collected by the Burpee Museum of Natural History, was the occasion for an international symposium on tyrannosaur paleobiology. This volume, drawn from the symposium, includes studies of the tyrannosaurids Chingkankousaurus fragilis and “Sir William” and the generic status of Nanotyrannus; theropod teeth, pedal proportions, brain size, and craniocervical function; soft tissue reconstruction, including that of “Jane”; paleopathology and tyrannosaurid claws; dating the “Jane” site; and tyrannosaur feeding and hunting strategies. Tyrannosaurid Paleobiology highlights the far ranging and vital state of current tyrannosaurid dinosaur research and discovery. “Despite being discovered over 100 years ago, Tyrannosaurus rex and its kin still inspire researchers to ask fundamental questions about what the best known dinosaur was like as a living, breathing animal. Tyrannosaurid Paleobiology present a series of wide-ranging and innovative studies that cover diverse topics such as how tyrannosaurs attacked and dismembered prey, the shapes and sizes of feet and brains, and what sorts of injuries individuals sustained and lived with. There are also examinations of the diversity of tyrannosaurs, determinations of exactly when different kinds lived and died, and what goes into making a museum exhibit featuring tyrannosaurs. This volume clearly shows that there is much more to the study of dinosaurs than just digging up and cataloguing old bones.” —Donald M. Henderson, Royal Tyrrell Museum of Palaeontology
Author: Kenneth Carpenter Publisher: Cambridge University Press ISBN: 9780521567237 Category : Nature Languages : en Pages : 394
Book Description
In the last two decades the study of dinosaur eggs and babies has proved a very profitable area of dinosaur research. This book is solely devoted to this topic and reviews our present state of knowledge in this area of paleontology.
Author: Kenneth Carpenter Publisher: Cambridge University Press ISBN: 9780521438100 Category : Nature Languages : en Pages : 360
Book Description
In recent years dinosaurs have captured the attention of the public at an unprecedented scale. At the heart of this resurgence in popular interest is an increased level of research activity, much of which is innovative in the field of palaeontology. For instance, whereas earlier palaeontological studies emphasized basic morphologic description and taxonomic classification, modern studies attempt to examine the role and nature of dinosaurs as living animals. More than ever before, we understand how these extinct species functioned, behaved, interacted with each other and the environment, and evolved. Nevertheless, these studies rely on certain basic building blocks of knowledge, including facts about dinosaur anatomy and taxonomic relationships. One of the purposes of this volume is to unravel some of the problems surrounding dinosaur systematics and to increase our understanding of dinosaurs as a biological species. Dinosaur Systematics presents a current overview of dinosaur systematics using various examples to explore what is a species in a dinosaur, what separates genders in dinosaurs, what morphological changes occur with maturation of a species, and what morphological variations occur within a species.
Author: Kenneth Carpenter Publisher: Indiana University Press ISBN: 9780253334978 Category : Nature Languages : en Pages : 714
Book Description
Offers the very latest information on dinosaur eggs, hatchlings and babies, as well as a detailed look at dinosaur courtship, mating, nests, and physical development.
Author: Peter L. Larson Publisher: Indiana University Press ISBN: 0253350875 Category : Nature Languages : en Pages : 458
Book Description
Accompanying CD-ROM has supplementary materials related to chapters 7 (color images of the black and white figures in the book), 11 (Flash-animated movie about tyrannosaurid postures), and 13 (skull bone atlas).
Author: Luis M. Chiappe Publisher: Univ of California Press ISBN: 0520200942 Category : Medical Languages : en Pages : 534
Book Description
"Mesozoic Birds is the first book to bring together world-renowned specialists on fossil birds and their importance to avian origins and, more importantly, it stresses a unified approach (cladistics) and presents the most anatomically detailed analyses available to date. No other study or collection of studies has ever done so much. How could the project not be welcomed by its audience of paleontologists, ornithologists, and evolutionary biologists!"—David Weishampel, editor of The Dinosauria "This is the first comprehensive volume dedicated to the relationships and evolution of the birds that lived during the Age of Dinosaurs. Its wealth of information and its diversity of viewpoints will ensure that this indispensable volume is used and discussed for many years to come."—Kevin Padian, University of California, Berkeley
Author: Peter Dodson Publisher: Princeton University Press ISBN: 1400887445 Category : Science Languages : en Pages : 369
Book Description
The horned dinosaurs, a group of rhinoceros-like creatures that lived 100 to 65 million years ago, included one of the greatest and most popular dinosaurs studied today: Triceratops. Noted for his flamboyant appearance--marked by a striking array of horns over the nose and eyes, a long bony frill at the back of the head, and an assortment of lumps and bumps for attracting females--this herbivore displayed remarkable strength in its ability to fight off Tyrannosaurus rex. It was also among the last dinosaurs to walk the earth. In telling us about Triceratops and its relatives, the Ceratopsia, Peter Dodson here re-creates the sense of adventure enjoyed by so many scientists who have studied them since their discovery in the mid-nineteenth century. From the badlands of the Red Deer River in Alberta to the Gobi Desert, Dodson pieces together fossil evidence to describe the ceratopsians themselves--their anatomy, biology, and geography--and he evokes the human dimension of their discovery and interpretation. An authoritative survey filled with many original illustrations, this book is the first comprehensive presentation of horned dinosaurs for the general reader. Dodson explains first the fascinating ways in which the ceratopsians dealt with their dangerous environment. There follows a lesson on ceratopsian bone structure, which enables the reader quickly to grasp the questions that still puzzle scientists, concerning features such as posture, gait, footprints, and diet. Dodson evenhandedly discusses controversies that continue, for example, over sexual dimorphism and the causes of the dinosaurs' disappearance. Throughout his narrative, we are reminded that dinosaur study is a human enterprise. We meet the scientists who charmed New York high society into financing expeditions to Mongolia, home of Triceratops' predecessors, as well as those who used their poker winnings to sustain paleontology expeditions. Rich in fossil lore and in tales of adventure, the world of the Ceratopsia is presented here for specialists and general readers alike. Originally published in 1996. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.