saadia Archive

Evolutionary Pressures in Mammals

EVOLUTIONARY PRESSURES IN MAMMALS Mammals are naturally distributed on all continents except Antarctica. They live in all oceans. EXTERNAL STRUCTURE AND LOCOMOTION SKIN The skin of a mammal consists of epidermal and dermal layers. It protects the animals from mechanical injury, microorganisms, and ultraviolet

Classification of Mammals

CLASSIFICATION OF MAMMALS Class Mammalia Mammary glands: hair: diaphragm: three middle-car ossicles; heterodont dentition;sweat, sebaceous and scent glands: four- chambered heart; large cerebral cortex. (a)     Subclass Prototheria This subclass formerly contained the monotremes. Monotremes have recently been reclassified, and this subclass now contains only

Diversity of Mammals

DIVERSITY OF MAMMALS Modern mammals have following characteristics: 1. They have hair on the body. 2. They have mammary glands. 3. They have specialized teeth. They have heterodont dentition 4. Three middle-car ossicics are present. 5. Diaphragm is present in them. 6. Their skin

Mammals Evolutionary Perspective

 MAMMALS EVOLUTIONARY PERSPECTIVE Tertiary period started about 70 million years ago. It was the start of the “age of mammals.” It produces adaptive radiation in the mammals. Extinction of many reptilian lineage also occurred in this period. The synapsid lineage of reptiles diverged from


OBJECTIVES OF BIRDS Multiple Choice Questions MCQs 1. The age of reptiles is: (a) Jurassic period    (b) Tertiary period (c) Secondary period   (d) Triassic period 2. Early synapsids were: (a) pulveosaurs            (b) Therapsids               (c)Parapsids                   (d) None 3. Diastema is present in: (a) Cynodonts             


SUBJECTIVE QUESTIONS IN BIRDS Why are birds called as “glorified reptiles”? Or Discuss phylogenetic relationships of birds. Discuss evolution of flight. What is the evolutionary significance of Archaeopteryx? Write note on diversity of modern birds. What is the significance of feathers in the birds?


CLASSIFICATION IN BIRDS Class Aves Adaptation for flight include: forelimbs are modified as feathered wings, endothermic, high metabolic rate, flexible neck, fused posterior vertebrae, and bones lightened by numerous air spaces. The skull is lightened by a reduction in bone. Presence of a horny

Birds feather flight & endothermy

THE BIRDS FEATHER FLIGHT & ENDOTHERMY EVOLUTIONARY PROSPECTIVE PHYLOGENETIC RELATIONSHIPS Birds are traditionally classified as class Aves. Birds have adaptations for flight. The major characteristics of this class are: 1. Their appendages are modified to wings. 2.  They body is covered by leathers. 3.