http://gigascience.com/ancient_reptile_had_two_heads.htm

 

I thought it was rather interesting.

I find it difficult to manage one brain... let alone two.

 

I wonder if this happened to a human, would they have two separate concioussnesses.

Yes two seperate concioussnessess. It's ultra rare in humans. But there is a living example in the states now.

 

http://www.geocities.com/heldenkline/Hensel.html

 

http://en.wikipedia.org/wiki/Abigail_and_Brittany_Hensel

Actually, two-headed reptiles are a common birth defect, usually caused by improper incubation temperatures or mold on the eggs. This is basically just proof that ancient reptiles were just as susceptible.

 

Mokele

I saw something on TV ages ago about a two headed tortoise(turtle in america). I think this is the same one...

 

http://news.bbc.co.uk/1/hi/uk/4006351.stm

I find it difficult to manage one brain... let alone two.

 

I wonder if this happened to a human, would they have two separate concioussnesses.

 

Talk to a Siamese twin and find out! Two brains, remember?

 

From the article "It is the oldest known reptile to suffer from a birth defect known as axial bifurcation. This happens when an embryo is damaged, and some body parts develop twice."

 

Too much retinoic acid at the wrong time during development is one way to do this. So this is not a species, but a birth defect within a species.