Chapter : 7. Heredity & Evolution
Vestigial Organs
Vestigial Organs : Vestigial organs are useless organs found in the body. These are present in reduced form.
Ex. wings of kiwi, limbs of snakes, the nictitating membrane of the eye, body hair and the muscles that move the ears.
During the period of evolution vestigial organs have become functionless.
Fossil Evidences : Fossils are the remains of the organisms that found in the ancient period. We can determine fossil’s age through the period of rock by radioactive material. Histological time scale is a chronological order of evolution history based upon the study of fossils.
Study of fossils known as palaeontology.
Petrification : Hard parts are preserved in this type of fossil.
Archaeopteryx :
A fossil bird show both reptilian and avian features - It had wing like birds, thecodent dentition and tail like reptiles. Hence, archeopteryx is a connecting link between birds and reptiles.
Connecting links :
Embryological Evidences:
The study of embryo from variours organisms reveals similarity in the early stages of embryo development & this theory suggests that these organism have evolved from common ancestors.
Eg. Embryos of fish, turtle, bird, pig & man shows the similarity during embryo development.
Ex. wings of kiwi, limbs of snakes, the nictitating membrane of the eye, body hair and the muscles that move the ears.
During the period of evolution vestigial organs have become functionless.
Fossil Evidences : Fossils are the remains of the organisms that found in the ancient period. We can determine fossil’s age through the period of rock by radioactive material. Histological time scale is a chronological order of evolution history based upon the study of fossils.
Study of fossils known as palaeontology.
Petrification : Hard parts are preserved in this type of fossil.
Archaeopteryx :
A fossil bird show both reptilian and avian features - It had wing like birds, thecodent dentition and tail like reptiles. Hence, archeopteryx is a connecting link between birds and reptiles.
Connecting links :
Embryological Evidences:
The study of embryo from variours organisms reveals similarity in the early stages of embryo development & this theory suggests that these organism have evolved from common ancestors.
Eg. Embryos of fish, turtle, bird, pig & man shows the similarity during embryo development.
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