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STRATIGRAPHY
Lesson 5 - Page 2

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A "species" in a biological sense refers to male and female organisms that can produce young. If organisms are living, this is easy to observe. However, if the organisms are extinct we only have their skeletal remains. In paleontology we compare similar fossil morphology and refer to them as a single species. We record when a new skeleton is observed and chart the range of that species. Sometimes we can see slight changes that branch off into another species.

In the present we can see the evidence of why organisms became extinct. The dodo bird is an example of a modern day extinction on Mauritius Island in the Indian Ocean. This 50 lb. bird was flightless with no enemies on the island. When humans came to the shores in the early 1500's they ate the bird for meat. Humans also brought pigs, rats, and monkeys that ate the dodo birdís eggs. Within 180 years after man came to its shores, the dodo was extinct by 1681. So why is one species important in the fossil record. Unfortunately when you take away one species another species will soon follow.

In the case of the fruit-eating dodo, it was recently noted that certain trees were no longer producing seedlings. There were 300 year old trees with no younger trees. It was concluded that the dodo ate the fruit and as the seeds passed through the gut, it prepared the seed for germination. Without the dodo naturally eating the fruit the tree would become extinct. To save the tree, turkeys are now being used to eat the fruit to produce seedlings.


Dodo bird


Mauritius Island

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