Here is a passage from http://www.alternativescience.com/darwinism.htm
If true, it [the claim that if you analyze the DNA of animals you find how closely or distantly they are related] would mean that animals neo-Darwinists say are closely related, such as two reptiles, would have greater similarity in their DNA than animals that are not so closely related, such as a reptile and a bird.
Fifteen years ago molecular biologists working under Dr Morris Goodman at Michigan University decided to test this hypothesis. They took the alpha haemoglobin DNA of two reptiles -- a snake and a crocodile -- which are said by Darwinists to be closely related, and the haemoglobin DNA of a bird, in this case a farmyard chicken.
They found that the two animals who had _least_ DNA sequences in common were the two reptiles, the snake and the crocodile. They had only around 5% of DNA sequences in common -- only one twentieth of their haemoglobin DNA. The two creatures whose DNA was closest were the crocodile and the chicken, where there were 17.5% of sequences in common -- nearly one fifth. The actual DNA similarities were the _reverse_ of that predicted by neo-Darwinism.[5]
[5] Patterson, Colin, presentation to the American Natural History Museum, 5 November 1981.
As far as I know the above is absolutely true, except for one important thing. Scientists do not claim that snakes and crocodiles are more closely related than crocodiles and chickens (or other birds). In fact, they claim just the opposite.
Take a look at the Tree of Life page. We'll start a little way up the tree, at Diapsida http://phylogeny.arizona.edu/tree/eukaryotes/animals/chordata/diapsida.html. Each fork in the tree of life represents a point where scientists believe two groups of living things share a common ancestor. Groups separated by forks lower in the tree shared common ancestors in the more distant past, and are therefore less closely related, than groups separated by forks higher in the tree. (Out of interest, mammals are separated from Diapsida, which is a group containing lizards, crocodiles, snakes and birds, at a branch somewhat lower down in the tree http://phylogeny.arizona.edu/tree/eukaryotes/animals/chordata/amniota.html.)
Diapsida is the smallest group which contains all three animals of interest in the above claim. It is split into two smaller groups:
Lepidosauromorpha
(lizards, sphenodon, and their extinct relatives)
Archosauromorpha
(crocodiles, birds, and their extinct relatives)
Within the group Lepidosauromorpha we find the group which holds snakes.
Squamata (Lizards and snakes)
Crocodiles and birds are in the other branch of Diapsida, called Archosauromorpha.
Archosauria (Birds, dinosaurs, crocodiles, and their relatives)
In the group Archosauria we find the split between birds and crocodiles.
Crocodylomorpha (crocodiles and their extinct relatives)
Dinosauria
(Dinosaurs and birds)
Lets take a look at that tree again.
Diapsida
|
+- Lepidosauromorpha
| |
| +- Squamata -- snakes
|
+- Archosauromorpha
|
+- Archosauria
|
+- Crocodylomorpha -- crocodiles
|
+- Dinosauria -- birds
The gist of this is that the last common ancestor that scientists claim existed between crocodiles and birds was more recent than the ancestor shared by crocodiles and snakes. The same common ancestor that joined crocodiles and snakes also joined birds and snakes. "Darwinists" say that birds, like chickens, are more closely related to crocodiles than they are to snakes. For this reason the genetic results above, showing that chickens are more closely related to crocodiles than snakes are to crocodiles, are not surprising.
Perhaps it shouldn't ever have been surprising. Although crocodiles and snakes share scaly skins and cold-bloodedness, they are otherwise very different animals. Birds also have scaly skin (on their feet), and they have four limbs, like crocodiles, whereas snakes have no limbs. Folk biology places snakes closer to crocodiles than birds. But looking at it from an evolutionary standpoint it is fairly evident (even without genetic data) that all three groups are widely separated, sharing common ancestors only in the very distant past. The question of which groups are more closely related and which are not requires close study, especially when comparing three such distantly related groups.