Origin of Dinosaurs, Mammals, Birds and Pterosaurs

By Daniel Habib

This book is about the time when giant reptiles ruled the world, on land (dinosaurs), in the sea
(sea monsters), and in the air (pterosaurs). It was a unique period, never to be repeated once mammals became the dominant tetrapods. Birds and mammals first appeared as well, but remained insignificant until these reptiles were already extinct.

The book is designed for a wide audience of age groups, ranging in age from seven years (my grandson Jake) to those of us at 77 (my age). The approach is holistic. For example, it describes relevant concepts within the geosciences, including how fossils record the history of life and how radioactivity provides us with the numerical ages of this history. Also, it describes the significant influence of mass extinctions and of the plate tectonic rearrangement of the continents.

The book is well-illustrated. There are more than 65 accurate drawings and additional cartoons.They are used to illuminate the written narrative.

Enjoy.

• Language: English
• Publisher: Xlibris US
• Release date: Sep 3, 2014
• ISBN: 9781499057102

Daniel Habib

"Professor since 1966, Queens College of the City University of New York. Retired 2007. Served 12 years as Director of the School of Earth and Environmental Sciences at QC and then an additional 12 years as Executive Officer in the CUNY Graduate School PhD program in SEES. Obtained five awards from the National Science Foundation for research using fossils to solve geological problems. Married 43 years to the same woman (Rochelle); three children (Joshua, Benjamin, Rebekah) and grandchildren".

Book preview

Part One. Introduction and Geological Background

Chapter One

INTRODUCTION

Preliminary Remarks.

Dinosaurs were the most successful of all land animals that lived during the Mesozoic Era, a time period called the Age of Reptiles. Although reptiles had already evolved in the previous era, called Paleozoic, it was only until the Mesozoic that they dominated the land, air and sea. The first flying reptiles were the pterosaurs. Mosasaurs, ichthyosaurs and plesiosaurs dominated the seas and, of course, dinosaurs dominated many different environments on land. Dinosaurs were the most ferocious of all the predatory land animals. They were also the largest of all animals that lived on land at that time.

Overview of the Mesozoic Era

The Mesozoic Era consists of three time periods, successively named Triassic (Tr), Jurassic (J) and Cretaceous (K). It lasted from approximately 251.4 Ma (millions of years ago) to 65.5 Ma (Table 1). It was very warm through much of its history, with interspersed periods of cooling. The average global climate reached as much as five degrees Centigrade (5⁰C) higher than it is today, with episodes that varied from dry to moist. All in all the warmer climate of the Mesozoic was most favorable to reptiles such as the dinosaurs. Living reptiles are ectotherms. They derive their metabolism from external heat sources such as solar energy. Conversely, mammals, including humans, are endotherms. We derive our energy from within. We wear clothing and bed cover to keep our body heat from escaping, as well as inhibiting the cold from entering within.

Reptiles are most active during daylight, but become inactive after nightfall. Even in the tropical heat of Komodo Island, Indonesia the monitor lizard called Komodo Dragon becomes less active at night. Witness the scene of the lioness and alligator competing to feed on the dead carcass of a juvenile hippopotamus in the dreadful heat of the African Serengeti day. The alligator prevails because of its metabolism which favors ectothermy. In general, lions prefer the evening for hunting, when it is cooler.

Table 1 Approximate ages of relevant Geological Periods.

Averaged ages are listed from the base of each unit in millions of years ago (Ma)

CENOZOIC Paleogene…………………………65.5 Ma

Mass Extinction of Life (65.5 Ma)

MESOZOIC

Late Cretaceous…………………..100 Ma

Early Cretaceous………………….145 Ma

Late Jurassic………………………161 Ma

Middle Jurassic……………………175 Ma

Early Jurassic………………………200 Ma

Mass Extinction (200 Ma)

Late Triassic………………………228 Ma

Middle Triassic……………………245 Ma

Early Triassic………………………251.4 Ma

Mass Extinction of Life (251.4 Ma)

PALEOZOIC

Permian……………………………299 Ma

Carboniferous……………………..359 Ma

Late Devonian…………………….385 Ma

Komodo Dragon

The komodo dragon (Varanus komodoensis) is the principal carnivore of Komodo Island, in the long chain of islands that comprise Indonesia. It is a large sprawling quadruped (10 feet long) with a long tail and short neck. It may weigh between 200 and 350 pounds. It is classified as lepidosaur diapsid and is related to other lizards and to snakes. It is an ectotherm which lives in an extremely hot climate (up to 140⁰ Fahrenheit in the summer). The island is tectonically active with frequent volcanic activity. Fires are frequent in the dry periods of summer. Fossils of Varanus occur in neighboring islands which are twice as large as the living species. The oldest fossils of this group of lepidosaurs go back 200 million years into the Age of Reptiles.

The komodo is a survivor. It is a dangerous animal that will eat almost any flesh that is available, either as a predator or scavenger, and no matter how spoiled the flesh might have become. It is a venomous animal. There are some 50 strains of bacteria that are infested in its mouth. This is a primary cause for the death of its prey, including humans. Some dozen people have been killed by komodo in the recent past. One victim, a German tourist, had part of his leg torn off. The tourist survived the attack but later succumbed to infection. In another case, a celebrity was bitten when he visited the animal at the San Francisco zoo. He was rushed to hospital and survived after a heavy dose of antibiotics.

The animal is unique in that it may remain active for a period of up to three months without food, based on the fat reserves that are stored in its tail. Bears hibernate. The komodo produces a large number of fertilized eggs which are buried in sediment. It is quite protective of its eggs. However, the offspring are completely on their own once they hatch. There is no parental care afterwards. As a matter of fact, dragons have been known to eat their young. A typically reptilian character is that the komodo cannot chew; rather, it rips a large chunk of flesh which it then swallows whole.

Plate Tectonics history of the Mesozoic Era

According to Plate Tectonics theory, a single supercontinent called Pangea had already existed by the beginning of the Triassic Period. It was an extraordinarily large continental mass which lay astride the equator (Figure 1.1), resulting in hot arid climates within continental interiors. The vegetation reflected this setting. The Age of Cycads is so-named for these naked seed plants (gymnosperms) which dominated the flora of the Triassic. Living cycads are presently concentrated in tropical arid regions of the world.

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Figure 1.1

Upper. Pangea. Tethys Sea to the east Lower.

Laurasia and Gondwana as separate continents

The ancient Tethys Sea was present as a deep invagination into the eastern margin of Pangea in the Early Triassic. By the time of the Middle Jurassic, Pangea had separated into two major continental masses, named Laurasia in the north and Gondwana in the south. The sutures separating the continents extended westward from the Tethys, forming what today is the North Atlantic basin. At first, the sutures produced a landlocked deep linear valley bounded by deep fractures called faults. The valley was initially filled with large lakes, similar to that of the deep linear East African Rift system today. The valley possessed red iron-oxide soils and dinosaur footprints. Large volumes of molten lavas and igneous intrusives initially formed in the valleys, and then formed the floors of the expanding ocean basins. Evidence of this tectonism is found today in the Triassic/Jurassic basins of eastern North