Say whether each statement is true or false, by the NCERT account, and correct the false ones…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Say whether each statement is true or false, by the NCERT account, and correct the false ones.
- The dinosaurs vanished from the Earth about 65 million years ago.
- The true reason for the disappearance of the dinosaurs is fully known.
- Some scientists think that birds are present day dinosaurs.
- The pouched mammals of Australia survived because there were no other mammals to compete with them.
- The first mammals were as large as the dinosaurs.
Need a reminder? The key ideaShow
Order in time: first cells, invertebrates, plants on land, fish with strong fins, amphibians, reptiles, mammals. A strip of cm for million years has one centimetre for million years, so a distance from the left end is .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) True.
Step 2. (b) False. NCERT says that we do not know the true reason. Some say a change in the climate killed them, and some say that most of them evolved into birds.
Step 3. (c) True. There is evidence that birds are present day dinosaurs.
Step 4. (d) True. Australia was cut off, so the pouched mammals had no competition.
Step 5. (e) False. The first mammals were small, and looked like shrews.
Answer: (a) true; (b) false; (c) true; (d) true; (e) false.
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