Dinosaur Two
Why did dinosaurs become extinct?
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  Facts
  • Dinosaurs became extinct around 65 million years ago because basically more were dying than were being born.
  • Nobody really knows why dinosaurs became extinct but scientists have some theories (educated guesses) based on the information that we do have.
  • One theory is that a meteorite crashed into earth creating a huge crater. The impact killed lots of dinosaurs but it also made a huge cloud of iridium (a very rare and dense metal) up into the atmosphere. The iridium dust cloud blocked out the sunlight, making a very long, cold, harsh winter. Without sunlight, the plants died, the herbivores eventually starved to death, and of course the carnivores ran out of food so they starved to death too. Eventually the dust cloud settled over the earth and the weather returned to normal, but the damage had been done.
  • Another theory is that a species of rodent-like mammals began to breed very quickly. These rodents ate the dinosaur eggs as fast as they were being laid. So while the old dinosaurs were dying simply of old age, there were no young dinosaurs to carry on reproducing, and the species died out.
  • One theory is that the dinosaurs got bigger, and bigger, until they were two big and awkward to hunt.
  • Another theory is to do with plants. Herbivores lived off plants, and when these plants evolved so that they were poisonous, the dinosaurs didnít notice and were all eventually poisoned to death. Because the Herbivores were the food source for the Carnivores, once they had all died, the Carnivores starved to death too.
 
  Did You Know?
  • Before dinosaurs became extinct they were roaming around earth for over 165 million years.
  • There are animals in New Zealand and around the world that are in danger of becoming extinct.
 
  Experiments
Find two weeds in the garden that are about the same type and are about the same size. Cover one with a box so that it doesnít get any sunlight and little air. This will be a little bit like the cloud of iridium some scientists think covered the earth before the dinosaurs became extinct. Leave the box there for several days then compare the two weeds.
What happened to the weed that had no sunlight and little air? When the iridium cloud covered the earth thatís what happened to all the plants and they all died.
 
  Investigation
Have a look at all the types of dinosaurs that existed. There are lots of really good books at the local library that have drawings and information about the place each dinosaur might have lived and the food they might have eaten.
Did they mostly live on land, in water, or in the sky? Can you think of any animals alive today that look a bit like a dinosaur?
 
  Jokes
Why did the dinosaur cross the desert?
Because chickens and roads weren't invented.
From Ben Higgins

What do you get when you cross a pig with a dinosaur?
Jurassic Pork!

What do you call a blind dinosaur?
A do-you-think-he saurus!
Or a I-don't-think-he-saw-us!
 




 
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