Class 12th Biology 2017 Set3 Delhi Board Paper Solution
Mention the evolutionary significance of the following organisms:
(a) Shrews
(b) Lobefins
(c) Homo habilis
(d) Homo erectus
The evolutionary significance of given organisms are as follows:
(a) Shrews
The first mammals were like shrews. These were long tailed, insectivorous, squirrel-like organisms. They gave rise to primitive primates. For example, leones, tarsiers at the beginning of the Palaeocene era.
(b) Lobefins
In 1938 a fish caught in South Africa happened to be a coelacanth which was thought to be extinct.These animals called lobefins evolved into the first amphibians that lived on both land and water. Modern day frogs and salamanders have evolved from them.
(c) Homo habilis
The first human-like primates, lived in Africa about 2 million years ago.Evidence shows that they haunted with stones weapons but especially ate fruits. They had brain capacity of 700 cc. Also called handy man as they were first and most skillful tool makers.
(d) Homo erectus
They appeared after Homo habilis , 1.7 million years ago. They had large brain capacities, i.e. 800-1100 cc and were omnivores. They used to hides to protect their body and buried their dead.
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