[Calamari]

If dogs were extinct and we had no knowledge of dogs at the present time and you dug up the skeleton of a fossilized dog, say a Great Dane or a Saint Bernard at an excavation site and a fellow "scientist" discovered a fossilized Chihuahua or Dachshund at another site the conclusion might be that you have different species when in reality you only have different breeds of the same species.

They could interbreed and produce off spring that look different from the parents. Carry this on for generations and you could not tell by looking who the ancestors were in several breeding cycles.

Are Neanderthals and Cro Magnons just different breeds and did a line of hybrids pop up that bred "true" and retained it's own outward characteristics generation after generation? Modern Humans

[night reader]

They could interbreed and produce off spring that look different from the parents.

You sayin' we're mongrels???