I don't really understand your statement
Answer:
Due to the large number of fossils being discovered at that time Darwin proposed that species change over long periods of time.
Explanation:
The theory of Darwin was that the species change in accordance to their environment, thus they develop advantageous traits so that they can be more competitive.
Answer:
pericardium
Explanation:
A double-walled membrane, the pericardium, separates the right and left chambers, preventing oxygen-rich blood from mixing up with the one without oxygen. So, the heart functions go smoothly. Deoxygenated blood enters the right atrium.
