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is held together by cement that was chemically precipitated, or by a fine-grained matrix of broken rock material. Depending on the rate of lithification, the processes involved in the formation of a rock from sediment, this consolidation can occur within a few years or over the course of millions of years. Sedimentary rocks are varied and are classified on the basis of their composition types of minerals and the texture size, shape, and arrangement of the sediment and associated cement or...
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FIGURE 9.6 Tetanurans as represented by allosaurids. A Giganotosaurus, a carcharodontosaurine of the Early Cretaceous of Argentina. B Yangchuanosaurus, a sinraptorid of the Late Jurassic of China. The former is on permanent display at the Fernbank Museum of Natural History, Atlanta, Georgia the latter is currently on display in the atrium of Hartsfield-Jackson International Airport, Atlanta. FIGURE 9.6 Tetanurans as represented by allosaurids. A Giganotosaurus, a carcharodontosaurine of the...
Instruments Used In The Laboratory
Binocular microscope Polarized microscope Compiling, analyzing, and storing field data transcribing of field notes image analysis of photographs modeling simulations morphometric analysis geographic distribution analysis phylogenetic evolutionary relationship analysis sending e-mail to colleagues. Scanning photographs, maps, or other illustrations for either image analysis, publications, or sending to colleagues for review. Examining specimens for detailed, microscopic features and measuring...
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FIGURE 11.9 The hadrosaurid Maiasaura with its nest and juveniles, based on associated body and trace fossil material from the Late Cretaceous Two Medicine Formation of Montana. Fernbank Museum of Natural History, Atlanta, Georgia restoration on loan from the Museum of the Rockies, Bozeman, Montana. FIGURE 11.9 The hadrosaurid Maiasaura with its nest and juveniles, based on associated body and trace fossil material from the Late Cretaceous Two Medicine Formation of Montana. Fernbank Museum of...
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...
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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...
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FIGURE 4.9 opposite Steps in excavation of a vertebrate fossil, in this case a partially exposed skull and other bones of a metoposaur, a large amphibian that lived at the same time and in this case, the same region as early dinosaurs, Chinle Formation Late Triassic , Arizona. A After cleaning the area, workers estimated the extent of the fossil and dug around the defined area. B Digging of the rock underneath the fossil established a pedestal. C One worker placed wet paper towels on the top to...
Locomotion Api
Marginocephalian locomotion is still a contentious issue in some respects, partially because of lack of evidence or too much contradictory evidence. For example, at the time of writing, no distal parts of the hind limbs from pachycephalosaurs had been recovered from the geologic record. Consequently, dinosaur paleontologists know little about pachycephalosaur locomotion. Because of the relatively short arms recovered from a few specimens, they probably were obligate bipeds but may also have...
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,...
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FIGURE 5.10 Hadrosaur skin impression, Late Cretaceous of North America. Mesa State Community College Museum, Tucumcari, New Mexico. anatomy and brain endocasts, nevertheless may provide indirect information suggesting that some dinosaurs were brightly colored, possibly for species identification and attracting mates Chapter 8 . Some researchers also propose that some dinosaurs were brightly colored because this trait is exhibited by some of their modern relatives some reptiles and birds . On...
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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....
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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...
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loquially known as the armored dinosaurs in recognition of their abundant, well-developed external bony parts, such as knobs and spikes. The only other dinosaurs that possessed body armor were titanosaurids Chapter 10 , thus this trait was apparently unusual outside of Thyreophora. Because of their impressive osteodermal accou-terments and the inference that all thyreophorans were herbivores, they are often used as an example of animals that engaged in an evolutionary arms race with their...
Cussion Questions Pcx
1. What paleontological evidence would convince you that Tyranno-saurus and Triceratops actually fought one another Would the evidence more likely come from body fossils or trace fossils, and why 2. What paleontological evidence would convince you that Pachyce-phalosaurus actually butted heads or at least flanks with one another Would the evidence more likely be from body fossils or trace fossils, and why 3. Given the following speculative masses and speeds for each genus of pachycephalosaur,...
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
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
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
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...
Bibliography Spx
Bakker, R. T. and Galton, P. M. 1974. Dinosaur monophyly and a new class of vertebrates. Nature 248 168-172. Czerkas, S. A. 1997. Skin. In Currie, P. J. and Padian, K. Eds , Encyclopedia of Dinosaurs. San Diego, California Academic Press. pp. 669-675. Dal Sasso, C. and Signore, M. 1998. Exceptional soft-tissue preservation in a theropod dinosaur from Italy. Nature 392 383-387. De Queiroz, K. and Gauthier, J. 1990. Phylogeny as a central principle in taxonomy Phylogenetic definition of taxon...
Dinosaur Eggs
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...
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LE 12.1 Representative genera of Ankylosauria with lt approximate geologic age and where they occur. An Ankylosauridae, No Nodosauridae. Basal thyreophorans Emausaurus, Scutellosaurus, and Scelidosaurus of the Early Jurassic were not included LE 12.1 Representative genera of Ankylosauria with lt approximate geologic age and where they occur. An Ankylosauridae, No Nodosauridae. Basal thyreophorans Emausaurus, Scutellosaurus, and Scelidosaurus of the Early Jurassic were not included
Bone Histology and Biogeochemistry
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...
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Because current cladistic analyses now suggest that Hypsilophodontidae is a para-phyletic grouping of basal ornithopods, the use of hypsilophodontid is used here to describe all euornithopods outside of the clade Iguanodontia and is not meant to connote a clade. In contrast to heterodontosaurids, hypsilophodontids are better known through complete or otherwise well-preserved skeletons of one species Hypsilophodon and fragments of about 10 other species. Hypsilophodontids occur in strata formed...
History of Dinosaur Studies
m Dinosaur Studies before the Renaissance Dinosaur Studies of the Recent Past Beginnings of a Renaissance and
Diet and Physiology How Much Did a Dinosaur Need to Eat
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...
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marine-deposited dinosaur remains, mainly the distal parts of the animals are preserved those parts that would have been dangling in the water and some of these bones exhibit the distinctive toothmarks or teeth of their shark or marine crocodile contemporaries. Whether scavenging happened on the land or at sea, it may mean that body parts of a dinosaur could have been carried far away from the original site of death. Physical processes probably caused the most dramatic changes in locale for a...
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...
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Of these, the latter factor is the most likely, and recognition in more recent years of this human-induced diversity has decreased the number of ceratopsian taxa. Thus, among taxonomists the lumpers triumphed in part over the splitters Chapter 5 . This is not to say that Triceratops did not undergo speciation over 3 million years FIGURE 13.3 Typical ceratopsian lower jaws. A Dentary and predentary of Protoceratops, Late Cretaceous of Mongolia Dinosaur Adventure Museum, Fruita, Colorado. B...
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2 the inclusion of numerous small bone fragments of the hadrosaur and 3 its occurrence in strata known to contain body fossils of tyrannosaurids, such as Albertosaurus and Tyrannosaurus. However, because occlusal surfaces were so narrow for tyrannosaurids and most other theropods, chewing would not have been very efficient. Hence an alternative hypothesis is that the bone fragments represent nipping of the bone material by the anterior teeth as it pulled meat off the juvenile hadrosaurid....
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...
Locomotion Ygo
Ornithopods were obligate bipeds, facultative bipeds, or quadrupeds, as suggested by their appendicular skeletons and verified by their trackways. The appendicular skeletons of heterodontosaurids and other non-iguanodontians imply that these lighter and smaller ornithopods were quicker moving than iguanodontians. Of course, ornithopod trackways, particularly from the Cretaceous, are very common in some parts of the world and constitute an excellent fossil record of their locomotion, which can...
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...
Dinosaur Teeth Herbivorous and Carnivorous
People with cavity-bearing teeth pulled from their jaws or who have seen X-ray photographs of their teeth have the opportunity to observe a few or most of the tooth parts and their orientations. Teeth have two primary layers, tough enamel on the outside and softer dentine on the inside. The part of the tooth exposed above the gumline of an animal is its crown, whereas the part within the socket is the root. In many cases, the root composed the majority as much as 75 of a dinosaur tooth. The...