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...

Info

Non-ceratopsid neoceratopsians are an interesting and varied group with a long history in dinosaur paleontology. For example, one of the most abundantly represented dinosaurs in the geologic record is Protoceratops andrewsi, a small-frilled, unornamented neoceratopsian that only reached about 2.5 meters in length. This neoceratopsian was postulated as the possible inspiration for the griffin, a mythical beast with lion and bird features whose legend arose out of central Asia, where skeletons of...

Sum

Evolution is both a fact and a theory, in that the change in a population between generations of species has been observed, but the explanation for how this process happens is still evolving. Darwin provided the first unified explanation for the origin of species and descent with modification of organisms, although his hypothesis has changed considerably with more fossil discoveries during the past 150 years as well as the addition of Mendelian genetics, which was further elaborated through the...

Paleobiogeography And Evolutionary History Of Marginocephalia

Torosaurus Latus Fossils

FIGURE 13.8 Cast of skull for the Late Cretaceous neoceratopsian (and ceratopsid) Torosaurus latus, from the Hell Creek Formation of South Dakota, a candidate for the largest skull possessed by any land animal. Utah Field House of Natural History, Vernal, Utah. FIGURE 13.8 Cast of skull for the Late Cretaceous neoceratopsian (and ceratopsid) Torosaurus latus, from the Hell Creek Formation of South Dakota, a candidate for the largest skull possessed by any land animal. Utah Field House of...

Cussion Questions Continued

Calculated radiometric ages indicating 125 Ma that are equi-distantly 1670 km away from a mid-ocean ridge 10. Discuss how plate tectonics relates to the following items a. Smog in Los Angeles, California. b. Sediments in the Amazon River of South America. c. The low population of Tibet. d. Materials composing a typical automobile. e. A dinosaur skeleton that was under more than 1000 meters of rock now being found at the surface, available for excavation and preparation.

Ethical Decisions and Their Impact on the Science of Paleontology

Two paleontologists, who began as friends, soon became bitter enemies after they started to compete for the same fossils in the same field area. This incident was exacerbated when one of the paleontologists publicly exposed a major scientific mistake made by the other. The paleontologist in error was so deeply embarrassed that he attempted to buy, with his own personal funds, all of the journals that contained his mistake. The two rivals soon began employing spies to report on the dinosaur...

Bibliography

J. and Eberth, D. A. 1998. The paleogeographic and strati-graphic distribution of ceratopsids (Ornithischia) in the upper Judith River Group of Western Canada. Palaios 13 160-169. Dodson, P. 1991. Morphological and ecological trends in the evolution of ceratopsian dinosaurs. Paleontological Contributions from the University of Oslo 364 17-18. Dodson, P. 1996. The Horned Dinosaurs A Natural History. Princeton, New Jersey Princeton University Press. p. 346. Dodson, P....

Accumulation and Burial

An accumulation of dinosaur bones in the geologic record may indicate the following A lack of movement sufficient to have carried the original bodies or bones from the site of the dinosaurs' death (an autochthonous assemblage). The cessation or insufficient momentum of a flow that carried the bodies or bones to that spot. A reworking of bones, possibly from several pre-existing bone beds, into a concentrated deposit. Dinosaur paleontologists should be very interested in a mass accumulation of...

What Is an Opinion

An opinion is an idea that is based more on how a person feels, and it may or may not be based on factual information. For example, someone might say, I really dislike Compsognathus (Fig. 2.4). When asked why, the person might say, Because someone told me that it was a scavenger and I don't like scavengers. In this instance, what this person has expressed is an opinion. A listener has few ways of knowing what evidence or rationale supports that feeling, as well as the subsequent statement....

Organization

The book as a whole is broadly divisible into two parts composed of an equal number of chapters. Chapters 1-8 introduce the major concepts associated with the study of dinosaurs, and provide an understanding of factual information in the basic sciences surrounding dinosaur studies (science literacy), as well as scientific methods used to investigate dinosaurs (scientific literacy). By the time a student finishes these chapters, he or she should be able to speak the language of science by asking...

Special Features

To provoke inquiry about the main topics, each chapter begins with an imagined situation in which some facet of dinosaurs is placed in the context of an everyday experience for the student. From this premise, questions are formulated, such as What was or was not a dinosaur (Chapter 1), Who made some of the original discoveries of dinosaurs (Chapter 3), How do people know the ages of rocks (Chapter 4), What did different dinosaurs eat (Chapters 9-13), and How could crocodiles, birds, and...

Anatomical Vocabulary for Dinosaur Skeletons Which Way is Up

Dinosaur paleontologists have their own set of terms that allows them to communicate effectively with one another regarding dinosaur anatomy. As demonstrated above, a lack of knowledge about anatomical vocabulary in particular is a barrier to understanding dinosaurs, but fortunately it can be overcome through some study and comparisons to what is already known. For example, many of the names given to bones in the human body are also applied to dinosaurs, so a few of these names should be...

And Others

The first discovered sauropod, Cetiosaurus, came from the Middle Jurassic of England and was described and named by Richard Owen in 1841. Unfortunately for dinosaur studies, he thought that it was a large, whale-like marine reptile. Not until later in the nineteenth century did investigators link it to other sauropods, such as those found in the western USA (Chapter 3). The oldest sauropods are from the Late Triassic (see Table 10.2), indicated by the fragmentary remains of Blikanasaurus,...

Growth

Growth series calculated for some ornithopod species, based on bone proportions, are partially to almost complete. Moreover, these data are supplemented by bone histology relating to growth lines and LAGs (Chapter 8). The Late Cretaceous hadrosaurid Maiasaura of North America is again well represented in this respect, with specimens ranging from possible newborns to full-sized adults. Partial growth series also are available for the Late Jurassic Dryosaurus and Late Cretaceous Hypacrosaurus of...

LE Representative genera of Ceratosauria with approximate geologic age and location

On the basis of only one or two specimens. Additionally, some of these specimens are incomplete or otherwise have scrappy remains. For example, Dilophosaurus is the most famous of ceratosaurs because of its starring role in the 1993 film Jurassic Park. Unlike most other dinosaurs in this movie, it also actually lived during the Jurassic Period. Nevertheless, Dilophosaurus is only known on the basis of seven specimens, all from Arizona. Part of this neglect for all things ceratosaurian may be...

Absolute Age Dating How We Know When Dinosaurs Lived

When geologists confidently say that dinosaurs as a group lived for, at a minimum, 165 million years, or 165 Ma (Latin translation of mega annus), they are referring to the considerable factual evidence supporting the vast amounts of time associated with the age of the Earth. That the Earth is about 4.6 billion years old is known through radiometric age dating, a method used to calculate absolute ages of rocks or other materials using radioactive elements. Radioactive elements have known...

Why Learn about Dinosaur Taphonomy

This chapter summarizes the Three Ds, its subject matter being death, decay, and disintegration. Taphonomy, the study of everything that happens to an organism's body after it dies, is a fascinating science. Taphonomy (from the Greek taphos, burial, and nomos, law) was first recognized as a science for studying the post-death phenomena associated with organisms by Russian paleontologist J. A. Efremov in 1940, although some of its principles were discussed by Leonardo da Vinci in the fifteenth...

Reproduction

The logistics of sauropodomorph mating is difficult to imagine but obviously it did happen many times. The traces of this activity in itself are either undiscovered or perhaps cover such a large scale that paleontologists do not recognize them. However, the results of successful mating and conception, eggs and nests, provide evidence that sauropodomorphs were oviparous animals, despite some conjecture (with no accompanying data) that they gave birth to live young. In fact, the two oldest...

Definition and Unique Characteristics of Theropoda

Theropoda (thero beast and poda foot) is a stem-based clade within Saurischia. Stem-based clades are those that have a shared common ancestor that is more recent than that of another group (Chapter 5). Theropoda is also a sister clade to Sauropodomorpha from the parent clade of Saurischia. A sister clade is a taxon that shares and splits from the same ancestral group as another taxon. In the case of theropods and sauropodomorphs, they had a common saurischian ancestor but then probably diverged...

Heterodontosauridae

Heterodontosaurids ( different toothed lizard), which lived only during the Early Jurassic and mostly in southern Africa, derive their name from their differentiated teeth, an unusual condition for any dinosaurian clade. In fact, some of their teeth are morphologically distinctive enough that they are known only in heterodontosaurids. These teeth, occurring in the areas of the former cheeks, have been described as chisel-like because they come to an edge at their crowns, which are also adorned...

Paleobiogeography and Evolutionary History of Sauropodomorpha

Sauropodomorphs lived on every continent, including the former subcontinent of India. Antarctica was recently added to their paleobiogeographic range, with the discovery of remains from a still-unnamed Early Jurassic prosauropod. With evidence gained from both prosauropod and sauropod body and trace fossils, paleontologists can confidently state that sauropodomorphs comprised a long-lived and widespread clade. Extending from the earliest of saurischian history in the Late Triassic (slightly...

Feeding

According to all known evidence, sauropodomorphs were obligate herbivores. Some paleontologists have proposed that the serrated teeth of prosauropods, such as Plateosaurus, reflect carnivorous behavior, and others have noticed some anatomical similarities between prosauropods and therizinosaurs (Chapter 9). Prosauropod teeth that are serrated and leaf-like show little sign of wear. Because grinding would involve direct contact between tooth rows with occlusion, shearing is instead favored as...

Definition and Unique Characteristics of Sauropodomorpha

Sauropodomorpha ( lizard-foot form) is a stem-based clade within Saurischia, like its sister clade Theropoda. Within Sauropodomorpha are two other stem-based sister clades, Prosauropoda and Sauropoda, which also had a common ancestor (Fig. 10.1). Prosauropods were originally interpreted as ancestral to sauropods, but recent analyses have supported their separate lineages from a common ancestor. Sauropodomorpha is distinguished as a clade on the basis of some of the following synapomorphies...

Dinosauria

FIGURE 1.3 Cladogram of the major dinosaur clades covered in this text, using Saurischia and Ornithischia hip structures as a basis for dinosaur classification. Although Linnaean and phylogenetic classification methods differ from one another, a comparison of categories used in each dinosaur classification shows that they use many of the same names. Unless antecedents such as clade or Order are used, confusion may result from not knowing which scheme a paleontologist is using. Consequently,...

Hints on How to Observe

Before any questions in science can be formed, observations have to be made. Observations, as mentioned earlier, can be gathered through all the senses, but in paleontology the two most important are sight and touch. A seeing-impaired paleontologist can still perform important work, as demonstrated by Geerat J. Vermeij, a blind paleontologist who has published detailed taxonomic identifications and interpretations of evolutionary and ecological relationships between fossil and modern gastropods...

Dinosaur Ichnology The Real Fossil Record for Dinosaurs

Welcome to the other fossil record of dinosaurs, trace fossils. Dinosaur ichnology, which is the study of their trace fossils, particularly tracks, provides an enormous amount of information that, until about 30 years ago, was viewed as more of a curiosity than an integral part of dinosaur studies. Many dinosaur books, especially those written prior to the 1990s, only treated dinosaur trace fossils as a sideline to skeletal data. In contrast, today, several dinosaur books and hundreds of...

Biomineralization and Biochemistry of Bones and Other Hard Parts

As might be expected, the most likely body fossil of a dinosaur encountered in either a field situation or a museum is ossified (formed into bone) material, such as bones, teeth, and some connective tissue (tendons). The primary reason for this bias in the fossil record is because mineralized tissue is more easily preserved than soft tissue (Chapter 7). Modern bones, teeth, and ossified tendons, called hard parts by paleontologists, are composed of a combination of mineral and organic matter....

Perspectives in the Past Present and Future of Dinosaur Studies

Advances in dinosaur studies in the past 25 years are exhilarating. The fast pace of these discoveries and the competition for coverage of these discoveries by the popular press ensures that the history of dinosaur studies will be continually changing, but all of this is still a direct result of the science behind such discoveries. One of the fringe benefits of the ongoing popularity in dinosaurs is that many professional paleontologists can write books for a general audience on their favorite...

Health

A great deal of evidence indicates that most theropods did have active lifestyles that included hunting, seeking mates, or moving together as family units. As a result, one could expect that they encountered more problems than dinosaurs whose food and mates did not move so fast. Theropods show the most evidence of health-related problems of all major dinosaur clades, although most were healthy animals. Apparently, the most common were limb injuries. For example, several theropod trackways show...

Geologic Maps

If a geologic map is drawn with superimposed topographic lines and other information, then it may provide most or all of the information that a typical topographic map would provide. However, these maps are, in some cases, difficult to read because geologic information overlaps topographic information. 2 Types and locations of bedrock units of different ages. 3 Contacts between different rock units. 4 Types and locations of surficial deposits (glacial deposits, river...

Social Life

Again, very little is known about thyreophoran sociality, other than reasonable hypotheses based on functional morphology and proximity of skeletal remains. Few thyreophoran skeletons are found adjacent to one another most are found as isolated individuals. This recurring circumstance, in stark contrast to the mono-specific accumulations of theropod, sauropod, ornithopod, and ceratopsian remains, seems to be evidence that most thyreophorans roamed either as individuals or in small groups. This...

Acknowledgments

Nancy Whilton of Blackwell Publishing deserves credit for urging me to write a prospectus for the first edition of this textbook, which I was pleased to learn was accepted and lauded by the editorial staff at Blackwell. My energetic, cheerful, and enthusiastic assistants in editorial development and production at Blackwell included Elizabeth Frank, Rosie Hayden, and Sarah Edwards. They deserve not only raves, but raises. This book would be much less educationally valuable without the...

Cranial Anatomy Related to Respiration

Endothermic vertebrates have large spaces within their nasal cavities to accommodate folded bony or cartilaginous structures, which were often lined with mucous membranes called respiratory turbinates. These structures are essential to endotherms because they help to conserve the water and heat associated with the near-constant breathing that endotherms use for their more active metabolism. Turbinates ensure that as much as 60 of the water moisture that is inhaled is absorbed (reclaimed) before...

Locomotion

Sauropodomorph ancestors were bipedal saurischians, and the earliest-known prosauropods may have been at least facultatively bipedal. Limb lengths indirectly indicate bipedalism in fossil vertebrates, in that the fore limbs are considerably shorter than the hind limbs. However, when the limbs are equally long, the animal could still have been bipedal, so another clue lies in the manus anatomy. When the manus is composed of lighter and more delicate bones, it is not likely to have been used for...

Hf lf

FIGURE 14.7 Plot of relative stride length versus dimensionless speed for different animals based on data derived from living cursorial vertebrates in terrestrial environments. (After Alexander, 1976, 1989.) FIGURE 14.7 Plot of relative stride length versus dimensionless speed for different animals based on data derived from living cursorial vertebrates in terrestrial environments. (After Alexander, 1976, 1989.) of 1.4 would have moved slower than our exemplified large theropod. This is related...

Preservation of Dinosaur Skin Impressions and Soft Part Anatomy

Some of the most memorable dinosaur finds in the history of dinosaur studies are of those that either have skin impressions, such as hadrosaur specimens (Edmontosaurus) discovered by the Sternbergs in Late Cretaceous strata of Alberta (Chapter 3), or otherwise show evidence of soft parts. However, not all dinosaur skin was soft, as evidenced by a few sauropods and most thyreophorans (Chapters 10 and 12). Skin impressions were typically preserved as fossils through mummification, a loss of water...

Social Behavior

Some of the social interactions interpreted for dinosaurs are also common behaviors in modern birds and mammals. These behaviors include 1 nurturing of young by some hadrosaurs (Chapter 11) 2 brooding of a nest by an oviraptorid (Fig. 8.8) 3 herding or other large group movements by theropods, sauropods, orni-thopods, and ceratopsians and 4 intraspecific competition in theropods, ornithopods, thyreophorans, and ceratopsians. In contrast, these behaviors are rare to absent in most modern...

Dinosaurs as an Example of Scientific Inquiry

The main purpose of this book is to introduce the study of dinosaurs as a scientific endeavor. What is and is not science is a major theme of this book, and the study of dinosaurs is an appropriate way to show how scientific methods are applied to real-world situations (Chapter 2). Because dinosaurs have been studied through scientific methods since at least the early part of the nineteenth century (Chapter 3), many examples are given of how these methods increased knowledge of dinosaurs....

What is Meant by Proof

Proof is a word associated with science that is commonly misapplied by non-scientists. For example, although media reports might say that scientists have proof of the relationships between birds and dinosaurs, a reporter actually would be more accurate in saying scientists have documented yet more convincing evidence supporting the relationships between birds and dinosaurs (Chapters 8, 9, and 15). Scientific methods do not deal with absolute proof of a hypothesis or even a theory proof is a...

Amniote Evolution and Diversification before the Dinosaurs

The origin of dinosaurs could arguably be traced back as far as the origin of life itself, which was about 3.8 billion years ago, but for the purposes of this book the evolution of amniotes is a more reasonable starting point. The development of an amniotic egg (one with an amnion, or fluid-filled sac surrounding the embryo Fig. 6.4), from amphibian ancestors for reproduction of offspring outside of aquatic environments, is often heralded as one of the major adaptations in vertebrate evolution....

Instruments Used In The Laboratory

Scanning internal structure of fossil specimens (especially skulls and eggs), and constructing three-dimensional images of structure with computer. Measuring fossil specimens electronically, and transmitting information to a computer. Capturing images of unmagnified or magnified fossils and transmitting digitized images to computer for analysis. Measuring atomic masses of elements and determining abundance of isotopes for radiometric age dating of rocks associated with dinosaur fossils or...

Early Scientific Studies of Dinosaurs The North and South Americans

Meanwhile, across the Atlantic Ocean, fossil evidence of dinosaurs was being discovered in North America in the latter part of the eighteenth and early part of the nineteenth centuries, although none of it was connected with dinosaurs at the time. The first probable dinosaur-related discovery in North America was in 1787, when anatomist Caspar Wistar (1761-1818) presented a bone from Cretaceous rocks of Woodbury, New Jersey to the American Philosophical Society, presided over by Benjamin...

Genetics and Natural Selection

Evolution is defined here as the change in a population between generations, where a population is a group of interbreeding organisms, such as a species (Chapter 5). Darwin originally summarized this process in the late nineteenth century with the phrase descent with modification, which is still apt today, despite much revision of his hypotheses since then. A population that goes through generations, from ancestors to descendants, comprises a lineage. Changes that happen to an individual...

Clade Stegosauria

Clade Stegosauria is named on the basis of the shingle-like appearance of the dermal plates on its back (stegos roofed and sauros lizard). Two overt characteristics help to distinguish them from other thyreophorans 1 parascapular spines, which are osteoderms evident as spikes on the shoulder regions and 2 parasagittal plates, which are the dermal armor restricted to two rows of vertically-oriented plates, parallel to but also lateral to the axial skeleton. Spikes also normally occur toward the...

What Is a Fact

A fact is a phenomenon that has an actual, objective existence. For humans to understand facts, observations must be made of them. Contrary to the old adage seeing is believing, these observations are not necessarily visual, but might be gathered through other senses. Observations regarding everyday facts could include seeing a sunset, smelling a flower, or hearing thunder. However, what is considered as a fact can change in terms of how it is interpreted. For example, the sun can be observed...

Pleural Of Phalanx

Phalanx Formula Theropod

FIGURE 5.7 Phalangeal formula applied to a human hand as an example. FIGURE 5.7 Phalangeal formula applied to a human hand as an example. is just below (posterior to) your thumb. Distal to the radius and ulna were, in order, the carpals (wrist bones), metacarpals, phalanges (plural of phalanx), and unguals (claws or hooves) the latter two compose the digits (or fingers). The phalanges are divided from the metacarpals in a human by the location of the knuckle joints and the same is true of...

Paleobiogeography And Evolutionary History Of Ornithopoda

Triassic forms are yet defined by paleontologists. However, some enigmatic dinosaurs have ornithischian features and a few anatomical similarities to ornithopods. These ornithischians made their earliest known appearances in Late Triassic strata of North and South America, as well as in South Africa. Richard Owen first described some of their remains in the nineteenth century, and he wrote of their laterally compressed teeth, which come to a peak but with denticles on their tops and thin enamel...

Preface

While this is indeed another dinosaur book, it is also a book about basic science that just happens to be about dinosaurs. In other words, the primary goal of this book is to teach basic scientific methods through the theme of dinosaur paleontology. My expectation in this respect is that dinosaurs provide a tempting hook for undergraduate non-science majors, who may already be enthused about dinosaurs but perhaps need some encouragement to learn basic science. Learning about science has two...

Ceratopsia

The prominent horns of Triceratops were what first caught the attention of O. C. Marsh when he saw its skull in 1887, leading him to first identify it as a fossil bison. Later, more cautious examination revealed that the horned skull belonged to a dinosaur, and it was promptly renamed in 1889 to Triceratops horridus ( horrid three-horned face). Marsh is credited with naming this famous dinosaur and the Family Ceratopsidae (using the Linnaean system), but the first ceratopsian named from the...

Ib

FIGURE 10.5 Diplodocus, the Late Jurassic sauropod that inspired a pub song. (A) Skeletal reconstruction Denver Museum of Science and Nature. (B) Left pes and ankle of Diplodocus, showing the large ungual on digit I. FIGURE 10.6 Amargosaurus, an Early Cretaceous sauropod from Argentina with unusually long vertebral processes. Trelew Museo de Paleontol gica, Trelew, Argentina. FIGURE 10.6 Amargosaurus, an Early Cretaceous sauropod from Argentina with unusually long vertebral processes. Trelew...

V

FIGURE 10.2 Important characters for Clade Sauropodomorpha distal part of the tibia covered by an ascending process of the astralagus, short hind limbs in comparison to the torso length, spatula-like teeth with bladed and serrated crowns, 10 elongated cervical vertebrae along with 15 dorsal vertebrae (25 presacrals), large digit I on manus. Thin and flat (spatula-like) teeth with bladed and serrated crowns. Minimum of 10 cervical vertebrae that are typically elongated and 25 pre-sacral...

Paleobiogeography and Evolutionary History of Thyreophora

Stegosaurs are firmly documented only in western North America, eastern Africa, western Europe, eastern Asia, and Australia. Moreover, their temporal distribution is limited to the Early Jurassic (at the earliest) through the Late Cretaceous, although Cretaceous stegosaurs are comparatively rare in relation to their Jurassic predecessors. Ankylosaurs are known from Middle Jurassic through to Late Cretaceous strata, and well-defined specimens have been recovered in North America, Europe, Asia,...

Reproduction and Growth

Evidence relating to thyreophoran reproduction is almost unknown and represents a huge gap in knowledge about their paleobiology. No nests or eggs, let alone embryos, from either ankylosaurs or stegosaurs have been discovered. In fact, of all the dinosaur eggs that have been described, none have been allied in even a general sense to thyreophorans. A little more is known about thyreophoran growth because of some skeletal material from the Late Jurassic for stegosaurs and the Late Cretaceous for...

Archosaur Evolution and Diversification

The Archosauria is defined as having, at minimum, the following characteristics Openings anterior to the orbits (antorbital fenestrae). Teeth with serrations compressed laterally and none on the palate. Differently shaped calcaneum. Some paleontologists place Archosauria within the clades Archosauromorpha and Archosauriformes, the latter originating from the former (Chapter 5). The majority of paleontologists agree upon the designation of Archosauria as a clade that had arrived by the Early...

Early Scientific Studies of Dinosaurs The Europeans

Prominent scientists of the fifteenth to the eighteenth centuries connected fossils to formerly-living organisms. Among them were Leonardo da Vinci (of Mona Lisa fame 1452-1519), Niels Stensen of Denmark (also known as Steno, Chapter 4 1638-87), Robert Hooke (1635-1703), and Robert Plot (1640-96) of England. Plot, a museum curator at Oxford, made the first known description and illustration of a dinosaur bone in 1677. The problem with his interpretation is that although he recognized the fossil...

Cussion Questions

What evidence would be needed to show that any sauropodomorphs lived in shallow aquatic environments but came up on land occasionally, as with modern hippopotamuses If one species of sauropodomorph was deemed to be aquatic but it was only capable of withstanding 1.5 atm of pressure, what would be the maximum depth difference between it in fresh water versus salt water 2. What evidence would be needed to support the hypothesis that some of the long-tailed sauropods used their tails as whips What...

Antecedent Of Dinosaurs

A necessary antecedent of dinosaur eggs was dinosaur sexual activity. The certainty of dinosaur sex as a prelude to their laying eggs is supported by the numerous observations of how mating in all egg-laying vertebrates is a necessary precursor to egg development. Fertilization of an egg without the help of a male, known as parthenogenesis, is common in nearly every major invertebrate clade but is known in only a few vertebrates (some amphibians and lizards). As a result, this process probably...

LE Representative genera of Prosauropoda with approximate geologic age and where they occur

But they were initially misidentified as human bones. A later diagnosis showed them as rightfully belonging to Anchisaurus of the Early Jurassic. Regardless of any such missteps, paleontologists immediately recognized the kinship of prosauropods and sauropods. Because the former preceded sauropods in the geologic record, they were considered as ancestral to sauropods. For this reason, they were given the name Prosauropoda, first dubbed in 1920 by Friedrich von Huene (Chapter 3). Although...

Classification of Dinosaurs

The method by which organisms or traces of their activities are named, which provides a framework for communicating through a classification system, is taxonomy. Thus, a name given to a group of organisms in a classification system is called a taxon (plural taxa). Dinosaurs can be classified in two ways. The more up-to-date of those two methods, cladistics (explained below), is the preferred one used worldwide by paleontologists (people who study the fossil record). The older, traditional...

Pace Angulation 180 Animal

FIGURE 14.1 Measurable parameters that can be derived from a well-preserved dinosaur track and trackway, assuming bipedalism. Note diagonal pattern to the trackway, which is typical for those made by dinosaurs. FIGURE 14.1 Measurable parameters that can be derived from a well-preserved dinosaur track and trackway, assuming bipedalism. Note diagonal pattern to the trackway, which is typical for those made by dinosaurs. individuals of some quadrupedal dinosaurs. For example, stegosaurs show five...

Dinosaurs as a Part of Popular Culture in Fiction

For reasons that perhaps can only be explained by psychologists, dinosaurs have always had a large popular appeal. This is evidenced by them being the subject of numerous books, comics, movies, television shows, Web pages, toys, models, and works of art in nearly every industrialized nation of the world. Recognition of this pervasive celebration of everything dinosaurian leads to a sociological observation dinosaur images in popularized media serve as the most direct source of many public ideas...

Pachycephalosauria

The most easily recognizable and well-known trait of pachycephalosaurs is an extremely thick, flat or domed bony skull (pachy thick and cephalia skull). For example, Pachycephalosaurus had a skull that was about 22 cm thick. This remarkable feature was formed by fusion of the frontals and parietals and the addition of FIGURE 13.5 Skulls of Late Cretaceous pachycephalosaurids. (A) Stegoceras as represented only by its fused frontal and parietals forming a high dome, a typical trait of...

Asthenosphere

FIGURE 4.8 The rock cycle as explained through plate tectonics, showing relationship of lithosphere and asthenosphere, as well as convergent, divergent, and transform-fault boundaries. interpreted as a result of plates moving laterally against one another without any accompanying volcanism. Evidence for this movement consists of the aforementioned stress eventually resulting in earthquakes measurable movement along the fault plane can be defined through offset features in the landscape. Hot...

MARY Continued

Probably served multiple purposes, such as protection, courting, intraspecific competition, and thermoregulation. Feeding was accomplished mostly through low-level grazing and browsing. Some specializations of skeletal features, such as deeply inset teeth, large hyoids, and expanded hindgut regions, meant that some thyreophorans were capable of processing huge amounts of food. Locomotion is little understood because of the scarcity of thyreophoran trackways, which means that hypotheses about...

Why Study Sauropodomorphs

Marsh provided the first, classic appraisal of Apatosaurus, which at that time was known A careful estimate of the size of Brontosaurus shows that when living the animals must have weighed more than twenty tons. The very small head and brain, and slender neural cord, indicate a stupid, slow-moving reptile. The beast was wholly without offensive or defensive weapons, or dermal armature. In habits, Brontosaurus was more or less amphibious, and its food was probably aquatic plants...

LE Common sedimentary rocks classified on the basis of composition and texture

Clastic Sedimentary Rocks formed through consolidation of previously broken rock material, mostly composed of silicate minerals. Shale. Mostly mud-sized particles (clay and silt), but shows parting of layers (fissility). Mudstone. Mostly mud-sized particles, no preferred parting of layers (sometimes synonymized with shale). Siltstone. Silt-sized particles. Sandstone. Sand-sized particles. Graywacke. Sandstone with an appreciable amount (> 15 ) of mud. Conglomerate. Sandstone containing...

Possible Causes of Injury Poor Health and Death in Dinosaurs

Typical, popular depictions of dinosaur deaths are melodramatic and limited to two scenarios mortal combat with other dinosaurs or a direct hit from an asteroid. The latter scenario has been added only recently, dating from 1980 (Chapter 16). Dinosaur deaths, depicted in fiction or other re-enactments, usually focus on dinosaur-versus-dinosaur conflicts, except where anachronistic humans are included to finish them off in some creative way (Chapter 1). But has anyone ever seen a depiction of a...

Tetanurae Avetheropoda and Its Numerous Clades

Tetanurae contains the theropods best known, such as Allosaurus, Tyrannosaurus, Velociraptor, Deinonychus, and Utahraptor. It also includes lesser-known genera, such as Oviraptor, Troodon, and Struthiomimus. The immediate ancestors of birds and their descendants are also placed within this clade, which has led most dinosaur paleontologists to state that birds are thero-pods (Chapter 15). The overlapping of theropod traits with those of birds is the main reason why Tetanurae and its members are...

Figure

Crylophosaurus ellioti, an Early Jurassic carnosaur from Antarctica. Auckland Museum, Auckland, New Zealand. remains on egg clutches (e.g., Oviraptor and Troodon) does not necessarily mean that these dinosaurs were female. Although the majority of birds that exhibit brooding behavior are female, it has also been documented in some male birds. For example, male emus (Dromaius novaehollandiaea), a large flightless bird native to Australia, sit continuously on egg clutches for about 55 days and...

Ankylosauria Ankylosauridae and Nodosauridae

Ankylosaurus Osteoderm

Ankylosauria derives its name from the encasement of its members in dermal armor (ankylos fused, sauros lizard), which is why many paleontologists describe them as tanks. This military allusion is apt in terms of the function of the armor, as certainly defense may have been one function, but its use for offense and species recognition is also possible. The following characters help to identify members of Ankylosauria (Fig. 12.2) A broad, laterally compressed skull with armor covering the...

Ceratosauria Coelophysoidea and Neoceratosauria

Although relatively less known than Tetanurae, the stem-based clade Ceratosauria ( horned lizard) includes abundant specimens of some interestingly varied theropods, whose remains have been found on all continents except Antarctica. Two stem-based clades are within Ceratosauria, Coelophysoidea and Neocer-atosauria. Coelophysoideans were the dominant theropods soon after the beginning of the geologic range for dinosaurs. Herrerasaurids in the Late Triassic were supplanted by coelophysoideans,...

Paleobiogeography And Evolutionary History Of Theropoda

Theropod body fossils are in Upper Triassic to Upper Cretaceous deposits on all seven continents, and so far their trace fossils are only missing from Antarctica. The small (1 meter long) possible theropod Eoraptor, of the earliest part of the Late Triassic, has been proposed as approximating the characteristics of a theropod ancestor because it shares some traits with theropods but also lacks others that define this clade. As mentioned earlier, herrerasaurids may also approximate the earliest...

Importance and Applications of Dinosaur Tracks

The most abundant and important dinosaur trace fossils are dinosaur tracks. Tracks have all of the advantages of most other trace fossils 1 they are potentially more abundant than other dinosaur body fossils 2 they may be preserved in rocks that do not normally preserve dinosaur body fossils and 3 they directly reflect dinosaur behavior where it happened. The aspects of dinosaur behavior that can be interpreted from tracks include, but are not limited to Where and in what environments they...

Defining Dinosaurs

Summary Discussion Questions Bibliography Because this book is about dinosaurs, probably the most appropriate way to start is by defining them. This is not an easy task, even for dinosaur experts, so here is a preliminary attempt A dinosaur was a reptile- or bird-like animal with an upright posture that spent most The term reptile-like is applied because dinosaurs evolved from reptilian ancestors, yet they were clearly different from present-day reptiles such as crocodiles, alligators, and...

Dinosaurs as Objects of Art and Artistic Inspiration

The first drawing of a dinosaur bone was in the seventeenth century, but it was interpreted as something entirely different at the time Chapter 3 . Much later, after their public recognition as formerly reptile-like animals, dinosaurs were depicted as dynamic creatures by many nineteenth-century artists. Dinosaurs have been a popular theme in art ever since, portrayed worldwide in drawings, paintings, and sculptures. More recently, multimedia approaches use photography particularly digital and...

Usgs

Your nine-year-old nephew draws a picture of a plesiosaur, which is a large, extinct marine reptile, some of which had long necks and well-developed fins. This plesiosaur is accurately depicted as swimming in an ocean, and in the sky above are a few pterosaurs, which were flying reptiles. One of the pterosaurs, however, is carrying a cow in its claws. Your nephew patiently explains to you that the dinosaur in the water is like the Loch Ness monster, and the dinosaurs flying overhead saw some...

Dinosaur Egg Biogeochemistry and Physiology

Dinosaur eggs contain a wealth of useful biogeochemical information pertinent to how dinosaurs took elements into their bodies and used them. Relevant chemical constituents of eggshells include Calcite, which provides information about the degree of mineralization of the egg as well as the effects of diagenesis Chapter 7 . Stable isotopes for oxygen, which can indicate the temperature of the original environment inhabited by the egglayer and for carbon, which can reflect dietary choices by the...

Dinosaur Skin Feathers and Organs

Skin and its derivatives in modern vertebrates, such as nails, feathers, hooves, and hair, are composed of the structural protein keratin. Because most skin is soft tissue and has lower preservation potential than skeletal material Chapter 7 , the discovery of dinosaur body fossils that have any evidence of soft tissues are the cause of much celebration, often followed by much debate. Both older and recent finds of evidence of soft tissue clarify better what some dinosaurs looked like in life,...

Tab

LE 10.2 Representative genera of Sauropoda with approximate geologic age and where they occur. interpreted as prosauropods, but a more careful examination of their traits indicates that they are more likely basal sauropods. Late Triassic sauropods are also identified by their probable tracks in Upper Triassic strata of the southwestern USA. Until the preceding revelations, which have only taken place in the past five years, the earliest known sauropod was the Early Jurassic Vulcanodon of...

Definition and Unique Characteristics of Thyreophora

Thyreophora is a stem-based clade within Ornithischia and Genasauria, and a sister clade to Cerapoda within Genasauria. Thyreophora contains two stem-based clades FIGURE 12.1 Cladogram showing interrelationships between basal thyreophorans Scelidosaurus, Scutellosaurus, and Emausaurus and other clades within Thyreophora, particularly Ankylosauria and Stegosauria. of importance Fig. 12.1 Ankylosauria, which includes Nodosauridae nodosaurids and Ankylosauridae ankylosaurids and Stegosauria...

Herrerasauridae

Herrerasauridae literally Herrera's lizard is named after Victorino Herrera, who in 1958 discovered its eponymous genus, Herrerasaurus, in the Late Triassic Ischigualasto Formation of Argentina Chapter 6 . Like many dinosaur clades, it is a provisional classification subject to revision with new evidence. For example, it was considered as a clade under Theropoda, but now some paleontologists place it outside of that clade. In fact, it is a sometimes-controversial assignment within Dinosauria....

Examples Of Marginocephalians

Marginocephalians Dinosaurs Images

Clade Marginocephalia, consisting of the relatively rare pachycephalo-saurs but also the very common most famous dinosaurs known, the Late Cretaceous Triceratops of North America. However, perhaps less known is that Marginocephalia is a group of dinosaurs that rivals Theropoda Chapter 9 and Ornithopoda Chapter 11 in its diversity. Largely because of the ceratopsians, Marginocephalia is also among the best-represented of Late Cretaceous dinosaurs through their skeletal remains, first discovered...

Toothmarks as Indicators of Diet

A toothmark is an impression left by the bite of an animal with teeth, regardless of what was being bitten. Toothmarks are trace fossils, whereas the medium they bit into are body fossils. Dinosaur toothmarks, first described and interpreted in 1908 Chapter 3 , have been so far only reported from bones, and no dinosaur toothmarks in fossil plant material are currently known. For those dinosaurs that fed on other animals, some left distinctive toothmarks on bones, which clearly indicates their...

Linnaean Classification of Organisms

Although the Linnaean classification scheme enjoyed a long history, for all practical purposes it has been replaced by cladistics Chapter 1 . One of the problems with the Linnaean system was that organisms with characters that did not fit into standard grades phylum, class, and so on were sometimes placed in between them, with the addition of an appropriate designated prefix. For example, superfamily includes more than one family but does not constitute an order, infraclass is within a class...

Theropod Skeletons

Stereochemistry Terminology

FIGURE 5.1 Orientation terminology as applied to anatomical features in vertebrates, using the skeletons of the Early Cretaceous theropod Deinonychus antirrhopus left and a modern human Homo sapiens right . FIGURE 5.1 Orientation terminology as applied to anatomical features in vertebrates, using the skeletons of the Early Cretaceous theropod Deinonychus antirrhopus left and a modern human Homo sapiens right . variations in a species and the nature of fossilization, paleontologists usually only...

Definition and Unique Characteristics of Ornithopoda

Ornithopoda bird foot , first named as a group by O. C. Marsh in the late nineteenth century Chapter 3 , was described in early literature as bipedal ornithis-chians. However, considering that bipedalism is now recognized as a probable ancestral trait for all dinosaurs, saurischians included, the definition of ornithopods has been refined considerably. Ornithopoda is now distinguished by the following characters, among others Fig. 11.1 Offset tooth row, where the maxillary teeth are higher more...

Appendicular Skeleton Legs and Feet

Dinosaur limb bones, especially if they are associated with a manus anterior foot, or hand and pes posterior foot , are wonderful finds, because they can provide information on how dinosaurs moved about their environments. Foot anatomy in FIGURE 5.5 Pectoral girdle of the Late Cretaceous hadrosaur Edmontosaurus of North America. Denver Museum of Science and Nature, Denver, Colorado. FIGURE 5.5 Pectoral girdle of the Late Cretaceous hadrosaur Edmontosaurus of North America. Denver Museum of...

Gastroliths Mostly for Herbivores

Some modern birds will swallow mineral grains several millimeters in diameter, which then reside in their gizzards and aid in the digestion of food by helping to grind tough material. Because birds do not have teeth, they need this mechanism to break down their food. The muscular action of the gizzard and the grinding caused by the mineral material helps to increase the surface area of the food for easier digestibility. Gastroliths were first described and interpreted from a Late Cretaceous...

Field Relations and Relative Age Dating

Relative Age Rocks

Geology is the primary scientific field associated with dinosaur studies, but people with little understanding of geology have found fossils of plants and animals, including dinosaurs Chapter 3 . However, some advanced knowledge of this subject is certainly helpful for continued success. Paleontology is the most readily recognizable subdivision of geology that applies to dinosaur studies, but other specialties, such as sedimentology, stratigraphy, and tectonics, are also essential to form a...

Axial Bones of a Dinosaur Hips Backbone Tail and Ribs

Hip Joint Dinosaur

One way to start with basic dinosaur anatomy is at the hips. Traditionally, the primary distinction between the two most fundamental clades of dinosaurs, the Saurischia and the Ornithischia, is their hip structure. This division was well described by Harry Govier Seeley in the late nineteenth century and bolstered later FIGURE 5.2 Left-lateral view of pelvic bones in relation to acetabulum and proximal end of femur for typical saurischian left and ornithischian right hips in dinosaurs. FIGURE...

Phylogenetic Closeness to Endothermic or Ectothermic Animals

According to phylogenetic analyses, birds and crocodilians are the closest living relatives to dinosaurs, but crocodilians are ectothermic and birds are endothermic. According to present paleontological knowledge, the common ancestor of cro-codilians and dinosaurs probably lived in the Early Triassic. In contrast, the common ancestor of dinosaurs and birds probably lived in the Middle to Late Jurassic. The common ancestry of crocodiles and dinosaurs was originally used as evidence of ectothermy...

Dinosaur Eggs

Structure Egg Shell

For reptiles and most of their descendants, which includes dinosaurs and birds, an egg is an enclosed yet porous mineralized or organic structure that contained or contains an amnion a fluid-filled sac surrounding a developing embryo Fig. 6.4 . An egg serves as a form of protection for an embryo that also keeps its nutrients in a restricted space while allowing the inflow of oxygen and exit of waste products such as carbon dioxide from the egg environment through its pores. Dinosaur eggs and...

Bone Histology and Biogeochemistry

Bone Histology Lags

Histology is the study of tissues how they are formed and how they function. Many tissues have been mentioned in this chapter and others bones, teeth, cartilage, muscles, blood, organs, and skin. Because the most commonly preserved former tissues of dinosaurs are bone, whenever a paleontologist is discussing dinosaur histology they are referring to bone histology, with only a few exceptions. But of course, such a discussion necessarily should be accompanied by considering how those bones may...

Diet and Physiology How Much Did a Dinosaur Need to

You are what you eat is a commonly applied phrase that relates the general health or disposition of a person to what they eat. In the case of dinosaurs and considerations of their physiological needs, the question might be better asked as You are how much you eat. As a general rule, ectotherms, kilogram for kilogram, will require less food than endotherms, but even some endotherms need more or less food than others of their thermoregulatory type. As different foods have varying caloric or other...

Preview of the Importance of Plate Tectonics to Dinosaur Studies

Why do we need to know about plate tectonics when studying dinosaurs Because everything on the surface of the Earth is affected by plate tectonics. It determines the location of the continents, mountain ranges, volcanoes, and earthquakes, as well as the configuration of the world's oceans. The location of the continents and their inherent geographic features affect the distribution of all land plants and animals. The entire global environment especially climate is influenced by the placement of...

Dinosaur Thermoregulation Other Considerations

The controversy over whether dinosaurs were endothermic, ectothermic, or some sort of physiology that did not qualify as either or varied on a species-to-species basis has caused the death of many trees because of the large number of papers written on the subject during the last 30 years. Of all topics in dinosaur studies, the popularity of the dinosaur thermoregulation discussion is rivaled only by the enduring debates over theropod ancestry and origin of flight in birds, and the causes of...

Phylogenetic Cladistic Classification

One of the major revolutions in dinosaur studies in the past 20 years has been in how they are classified, which is now accomplished through cladistics. Although evolutionary theory has been an essential part of biology and paleontology since the late nineteenth century, cladistics was not proposed in the scientific literature until 1950, and even then it did not become well known in mainstream scientific circles until 1966. This change was prompted by publication of a book in English that...

Outline of Main Dinosaur Groups Using Cladistics

Cladistics works as a classification system by showing how organisms with certain inherited traits have common ancestors, which makes any organism with those characters a member of a clade. Consequently, all animals that have a notochord, pharyngeal gill slits, and a dorsal nerve cord belong to Chordata. Classification of animals with these shared traits places humans in the same clade as sharks and Dinosauria. Similarly, the formation of bones in vertebrates is an ancestral trait that...

Dinosaur Models and the Estimation of Dinosaur Weights

An example of how science, art, and popular culture can be combined is through information derived from models of dinosaurs. Dinosaurs are often associated with huge sizes, but how can the question How big were dinosaurs be answered This book refers to the kilograms or metric tonnage 1000 kg, which equals 2200 pounds of a particular dinosaur, even though no one has actually weighed a living or even recently dead one. Arriving at such figures requires a few simple principles of physics, a little...

Stomach Contents Halfway Through

Actual remains of plants or animals in the abdominal region of a dinosaur seemingly represent unambiguous evidence supporting hypotheses about what dinosaurs ate. However, considering that fossilization of any dinosaur part was a rare event Chapter 7 , finding a specimen preserved with parts or all of a recent meal in the location of its former innards is always a surprise. The rare reports of dinosaur stomach remains provide a glimpse of a dinosaur's last meal that, despite being a sample of...