PL HEL A sprig of an Elodea plant was placed in a test tube. the test tube was then placed in
sunlight
The bubbles of gas in the diagram are composed mainly of

hydrogen

nitrogen

oxygen

carbon dioxide

I think that the differences between the skull shape and brow size have to deal extra protection needed , especially due to the eye shape. The shorter teeth were for the more evolved species which used tools and were herbivores or omnivores that did not need sharp teeth to tear flesh as the other which primarily hunted themselves and ate mostly meat.

Explanation: