Sunday
April 26, 2015

Homework Help: Biology

Posted by Kim on Sunday, April 14, 2013 at 4:39pm.

PLEASE HELP!!!!
1. How many millions of years ago did sharks first appear? (Make sure you are looking for animals that only have cartilage skeletons).
2. How many millions of years ago did bony fish (like the perch) first appear?
3. How many millions of years ago did amphibians first appear?
4. How many millions of years ago did reptiles first appear?
5. How many millions of years ago did modern birds (aves) appear?
6. How many millions of years ago did mammals first appear?
7. How many millions of years ago did humans first appear? (This date will vary depending on the source you pull from but you will at least be in the general proximity).

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