Origins of dinosaurs

ORIGIN OF DINOSAURS

A Term

Presented to (Name of professor (Name of Institution

In Partial Fulfilment

Of the Requirement for the Degree

Bachelor of Arts

By (Your name

10th October , 2008

Introduction

The origin of dinosaurs and the subject has different interesting myths and facts to it . The term dinosaur originated a scientific term `Dinosauria 'which refers to a varied group of animals exhibiting different living modes . Dinosaurs were reptiles that lived during the Mesozoic era about 165 million years ago . Dinosaurs were a subgroup of

archosaurs which is a group that includes birds and crocodiles Dinosaurs of the Mesozoic period left behind several clues about the way they looked like . Their fossils also give us a clue of the way of life of the dinosaurs . Some dinosaurs had primitive feathers while others had thick bumpy skin (Weishampel et al , 2004 pp 376-398

Since dinosaurs were reptiles , they were hatched from eggs . However the dinosaurs could neither fly nor live in water . The species is one of the world 's known large and energetic animal . The dinosaurs were tall and long some measuring about 100 feet long although there were small dinosaurs as small as the size of a chicken . Most of the dinosaurs were medium sized

History of origin

Dinosaurs emerge in the Triassic . In the Permian period , several vertebrates had developed among the mammalian group and some lizard like reptiles . During this period , the climate became extremely hot and dry which led to desertification of vast parts of the earth . Several species were extinct and only a few survived at the beginning of Triassic . The survivors included diapside reptiles which sought shelter under rocks and looked for food at dawn and during sunset when the temperatures were favorable . When the temperatures became endurable , the modern snakes and lizards evolved from those reptiles

In early Triassic when the climate became more endurable , and plants began to spread , another group of the reptiles evolved into plant-eating rhynchosaurs . Several species of the rynchosaurs emerged with characteristic tall clumsy bodies . The different rynausers later evolved into dinosaurs . There were different types of dinosaurs which lived at different times . Some dinosaurs walked on two hind limbs called bipedal while others moved on four limbs called quardrupedal . Dinosaurs food can be determined by the structure of their teeth . From the fossils found , dinosaurs fed on crops such as trees

Classification of Dinosaurs

Dinosaurs are a clade of archosaurs and lies within the phylum Chordata There are several classifications of dinosaurs but the most commonly used is Benton classification . According to Benton , all dinosaurs fall under the series Amniota , Class Sauropsida , a sub class Diapsida Division Archosauria . Benton divided dinosaurs into two major s Saurinchia and Orinthischia . The classification of dinosaurs is complex and wide (Benton , 2004 pp 223-345 Extinction of dinosaurs

Dinosaurs originated some 165 years ago and they became extinct about 65 million years ago . The extinction of dinosaurs is a mystery . Some scientists argue that dinosaurs became extinct naturally through...