Heritage and evolution class 10
Fossils :-are the remains of organisms which lived long ago.
From the study of fossils we can know their structures and the time period in which they lived. The fossils of complex and recent organisms are found closer to the surface of the earth and the fossils of simpler organisms are found deeper inside the earth. The age of fossils can be determined by Radio Carbon Dating. The study of fossils show evolution of simpler forms into complex forms and their evolutionary relationship.
Tree trunk fossil Fish fossil (Knightia)
Ammonite – Invertebrate Trilobite – Invertebrate Dinosaur skull – Rajasaurus
heritage and evolution class 10
Evolution by stages :-
Complex organisms and its organs developed from simpler organisms gradually over generations.
i) Evolution of eyes :- The eyes of planaria are just eye spots to detect light. It developed gradually into a complex organ in higher animals.
ii) Evolution of feathers :- Feathers were first developed in dinosaurs and used for protection from cold. Later birds used them for flying.
iii) Evolution by artificial selection :- Humans cultivated wild cabbage for over 2000 years and produced different vegetables from it by artificial selection.
Eg :- Cabbage – by selecting short distance between the leaves.
Cauliflower – by selecting sterile flowers.
Kale – by selecting large leaves
Kholrabi – by selecting the swollen stem
Broccoli – by arresting flower growth