Neanderthals: Subspecies or Separate Species Than Humans?

What does the current research say about Neanderthals and Homo Sapiens?  Are Neanderthals considered a subspecies of humans, or does science classify them as a separate species.   What does the evidence say?

Mammal Transitionary Fossils

Research what kind of transition fossils exist that shows evidence that mammals evolved from reptilian ancestors.  Include the descriptive evidence that supports this phylogenetic link.

Evolution of the Eye or of Flight

Research how flight evolved.  How many times has it evolved and in what kind of organisms?  What kind of evidence is there?

OR

Research how eyes evolved.  What kind of evidence is there that explains the process of complex eyes being created through natural selection?