Cambridge University Press

Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, Sao Paulo 40 West 20th Street, New York, NY 1001 I -421 I, USA Information on this title www.cambridge.org 9780521811724 Cambridge University Press 1996,2005 This book is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published 1996 Reprinted 1996,2001 Second...

Taphonomy Before burial

Consider what happens to a dinosaur - or any land-dwelling vertebrate -when it dies. If it is killed, it can be disarticulated (dismembered), first by the animal that lolled it, and then by scavengers. In modern environments, the best known of these scavengers are vultures or hyenas, but there are smaller animals of far greater significance, such as scarily efficient carrion-eating dermestid beetles. Of course most of the heavy lifting in the world of decomposition is done by bacteria that...

CHAPTER

Pachycephalosauria ramrods of the Cretaceous Figure 8.1 (see p. 147). The flat-headed, thick-headed Homalocephale, best-known of all pachycephalosaurs. Through a dense thicket come the deep sounds of thuds, slaps, and scuffling. Beyond these shrubs in a large clearing are a dozen or more pachycephalosaurs - Homalocephale - their broad thickened heads fringed with an array of small knobs and horns. Many are slowly foraging for succulent leaves and fruits in the undergrowth, while two of the...

Evolution Organic evolution is a fact

By saying organic evolution is a fact, we mean that, if one accepts that the human mind, with its strengths and limitations, is capable of understanding aspects of the natural world, and that scientific 3 Cladistic methods were first developed and articulated by an entomologist, Willi Hennig, in Grundzuge einerTheorie der phylogenetischen Systematik ( 1950). Hennig's work had a minor impact on European biologists, but it was not until the 1966 publication of an English translation (entitled...

Criterion

Dinosaurs were terrestrial beasts through and through, which means that their bones will generally be found in river systems, deserts, and deltas. Dinosaur remains, however, are known from lake deposits and from near-shore marine deposits. Clearly they lived neither in lakes nor in the ocean. In such cases, if the bones are articulated, the bloated carcasses may have floated out into the water, and eventually sunk and been buried. If not articulated, they may have been washed out of the mouths...

Heat retention in continents and oceans

Continents (land) and oceans (bodies of water) respond very differently to heat from the sun. In the height of summer, we cannot walk barefoot on cement, and yet we can cool off in a pool. At night, the cement cools off rapidly then, the pool seems warm. Because fluids are mobile, heat can be more easily distributed through a larger area in fluids than in solids. While solids quickly become hot to the touch, just a short distance below the surface, temperatures remain cool (a property that...

The origin of the Dinosauria

No doubt we all think we know what a dinosaur is - just by saying the word dinosaur we imagine Tyrannosaurus, Apatosaurus, or Triceratops, or any of the large land-lubbers from the Mesozoic Era. Among the uninitiated, an ichthyosaur, a plesiosaur, or one of the other sea-going reptiles of the Mesozoic bestiary (none of them are dinosaurs) may come to mind. Worse yet, a few people envision as dinosaurs mere youngsters, such as the 100,000-year-old woolly mammoth. It turns out that the question...

Crocodylia

Seeley's evolutionary scenario of the origin of dinosaurs. Seeley was not a natural group Figure 5.3 . This major theme, that dinosaurs were diphyletic i.e., having two separate origins , was continued well into the twentieth century, principally by Friedrich von Huene. Throughout his remarkably long career he published actively from the early 1900s to the 1960s , von Huene's studies came to epitomize independent dinosaur origins. According to him and many who came after,...

P

Cladogram of basal Iguanodontia. Derived characters include at I premaxilla with a transversely expanded and edentulous margin, reduction of the antorbital opening, denticulate margin of the predentary, deep dentary ramus loss of sternal rib ossification, loss of a phalanx in digit III of the hand, compressed and blade-shaped prepubic process at 2 strong offset of premaxilla margin relative to the maxilla, peg-in-socket articulation between maxilla and jugal, development of a...

Info

Easy Drawings Tuatara

Cladogram of the Chordata. Because this is a book about dinosaurs and not all chordates , we have provided diagnoses for only some of the groups on the cladogram. Bars denote the shared, derived characters of the groups.The characters are the following I pharyngeal gill slits, a notochord, and a nerve cord running above the notochord along its length 2 segmentation of the muscles of the body wall, separation of upper and lower nerve and blood vessel branches, and new hormone and...

Bat Bird Cladograms

Cladogram With Multiple Characters

Figure B3.1.2 Because each pair of ciadograms in Figure B3.1.1 is commutatively equivalent, there are really only three ciadograms under consideration. include computers, since a digital watch has the shared, derived characters of computers.The cladogram suggests that the term watch does not describe an evolutionarily meaningful monophyletic group, in the sense that a cladogram that includes digital watches, wind-up watches, and quartz watches must also include computers, as well as a variety...

Sigmoidal Border Ilium

Cladogram Pachycephalosaurus

Cladogram of Cerapoda, emphasizing the monophyly of Pachycephalosauria. Derived characters include at I thickened skull roof, frontal excluded from orbital margin, tubercles on posterolateral margin of squamosal, thin, plate-like basal tubera, double ridge-and-groove articulations on dorsal vertebrae, elongate sacral ribs, caudal basket of fusiform ossified tendons, ilium with sigmoidal border medial process on ilium, pubis nearly excluded from acetabulum, tubercles on squamosal,...

Other kinds of fossil

Bones are not all that is left of dinosaurs. Occasionally the fossilized feces of dinosaurs and other vertebrates are found. Called coprolites, these sometimes-impressive relics can give an intestine's-eye view of dinosauri-an diets. Likewise, as we shall see later in this book, eggs and skin impressions have also been found. Still, the single most important type of dinosaur fossil, other than the bones, themselves, are trace fossils. Dinosaur trace fossils sometimes also called ichnofossils...

Growth of a prehistoric time scale

Where were the continents during the time of the dinosaurs There can be little doubt that geology's greatest contribution to human knowledge is the development of the Geological Time Scale. This is the extremely complicated framework that reveals deep time to us, as well as the means by which we develop our understanding of the grand pageant that is the history of life on earth. The job is hardly finished the eminent stratigrapher W. B. N. Berry, writing a book on geological time, entitled it...

Moral

Monkonosaurus

This story has a simple moral With which the wise will hardly quarrel Remember that it scarcely ever Pays to be too bloody clever normal expansion of the nerve cord that passes through this region, giving off nerves to the hindlimbs and continuing backwards to the tail. While this situation was to be expected, the canal - especially at the front of the sacrum - was proportionately larger than might have been expected in order merely to control the legs and tail that is, it was much too large...

Behavioral Aspects Of The Huayangosaurus

Huayangosaurus Skeleton

Left lateral views of the skeletons of a Huayangosaurus, b Dacentrurus, and c Lexovisaurus. Figure 6.4. Left lateral views of the skeletons of a Huayangosaurus, b Dacentrurus, and c Lexovisaurus. Obviously even these running speeds were not of much importance to a hungry stegosaur, for these animals were herbivorous. Their general body form large abdominal region for a capacious gut , small head, toothless snout, and simple blunt teeth send a clear message that these animals ate...

Relative age dating

Relative Age Dating

The seventeenth century Danish naturalist Nicholas Steno3 was the first to recognize that 1 in any vertical, stacked sequence of sedimentary rocks, the oldest rocks are found at the bottom and successively younger-aged rocks are found above, with the youngest occurring at the top a observation now termed the law of superposition and 2 all sedimentary rock sequences were originally horizontal although subsequent geological events may have disrupted their original orientation in space . That...

After burial

Permineralisation

Bone is made out of calcium sodium hydroxyapatite, a mineral that is not stable at temperatures and pressures at or near the surface of the earth. This means that bones can change with time, which in turn means that most no longer have original bone matter present after fossilization. Replacement and or permineralization Replacement and or permineralization Isolated bones buried and mineralized Figure 1.2. Two endpoint processes of fossilization. In both cases, the first step is the death of...

Discovering order in the natural world

Car Cladogram

Around us there are consistent patterns that obviously constitute order in nature. To cite two simple examples, all plants with flowers have leaves, and all birds have feathers. Indeed, the correlation between birds and feathers is so consistent in our modern world that we might go so far as to identify a bird as such because it has feathers. Going further can we use features such as leaves and feathers to discover underlying patterns of organization among all organisms In other words, is there...

Part Ii

Cladogram Thyreophora

Ornithischia armored, horned, and duck-billed dinosaurs Ornithischia, one of the two major clades of dinosaurs, was first recognized by Harry Govier Seeley of Cambridge University, England, in 1887, but little could he have guessed at that time that ornithischians were such a diverse and anatomically wide-ranging group of closely related dinosaurs. Since then, we have learned an immense amount not only about the existence of new ornithischian taxa e.g., Pachycephalosauria, Heterodontosauridae...

Back to the past the Mesozoic

Mesozoic Era

The Mesozoic Era it would seem stranger to us than the Land of Oz. The big land animals were dinosaurs, not mammals. You couldn't receive a dozen red roses roses - or for that matter, any flowers - did not appear until the Mesozoic was more than half-way over. There were no lawns to mow because there was no grass. Until well into the Mesozoic, you couldn't hear birds singing because there were no birds. Indeed, at the beginning of the Mesozoic, the very continents themselves were connected, and...

Interrelationships of vertebrates

What is a dinosaur and where does it fit in among other vertebrates The answer to this question uncovers remarkable things not only about dinosaurs but also about many of the vertebrates living around us. Here, we will address questions such as How many times has warm-bloodedness evolved in the vertebrates answer at least two, possibly three times How many times has powered flight been invented by vertebrates answer three independent times , Is a cow a fish answer in an evolutionary sense,...

Part

Axial Vertebral Dinosaurs

First coined by Cambridge University's H. G. Seeley in 1887, Saurischia originally consisted of Sauropodomorpha Chapter 11 and its sister-taxon Theropoda Chapters 12,13, and 14 . Seeley imagined saurischians as having a different primitive archosaurian thecodont ancestor from that of ornithischians Chapter 5 , and thought of dinosaurs as a heterogeneous group of advanced archosaurs. A modern view includes Sauropodomorpha and Theropoda as well as a few primitive taxa that appear to be neither...

Lu

Cladogram of Hadrosauridae. Derived characters include at I three or more replacement teeth per tooth position, posterior extension of the dentary tooth row to behind the apex of the coronoid process, absence of the surangular foramen, absence or fusion of the supraorbital to the orbit rim, long coracoid process, dorsoventrally narrow proximal scapula, very deep, often tunnel-like intercondylar extensor groove at 2 absence of the coronoid bone, reduction in surangular contribution...

1

Heterodontosaurus Skeleton

Ornithopoda the tuskers, antelopes, and mighty ducks of the Mesozoic Ornithopods had it all. Some had tusks projecting from the corners of their mouths, some had spikes on their thumbs, some had more teeth than just about any other kind of animal, some sported hollow crests atop their heads, and all had long tails that projected straight back from their hips. Many must have had the grace of a running antelope. Ornithopods had one of the longest reigns of all dinosaur groups, lasting for most of...

BOX

Conifers Deciduous Muttaburrasaurus

Hypotheses that didn't go the distance In the history of the study of ornithopods, habitats and anatomy conspired to put some of these animals in exotic places and give them unusual locomotor skills. For example, hadrosaurids were once regarded as amphibious, in part because the tail was long and deep great for sculling in the water , the hand appeared to be webbed, and jaws were deemed too weak to handle anything but soft aquatic vegetation. Not true in all three cases. In a similar fashion,...

Styracosaurus Skull

Agathaumas Skeleton

Cross-section through the upper and lower jaws of Triceratops, illustrating, a high-angle slicing-and-dicing motion of the teeth and b internal view of the dental battery in the lower jaw of Triceratops. Figure 9.4. Cross-section through the upper and lower jaws of Triceratops, illustrating, a high-angle slicing-and-dicing motion of the teeth and b internal view of the dental battery in the lower jaw of Triceratops. like beak. The hooked rim of the rostral bone covered by a sharper...