>>I disagree. He clearly understands phylogeny.>>

Thank you for your objectivity.

>>The thing is that this person supports the infusion of subjectivity in order to preserve historical mistakes.>>

Historical mistakes, if it means polyphyletic taxa, should not be condoned. I do not condone such mistakes. If a taxon is polyphyletic, as Pachdermata was clearly so, then such a taxon would need to be disqualified. There are of course many taxa that have been delimited historically that are perhaps not to the liking of the cladists or their fans, but these taxa are by no means mistakes if the Darwinians and a vast majority of biologists world wide continue to recognize them. Besides, cladists make mistakes constantly. One of the biggest ones is the bird-theropod lexus. It is a polyphyletic group, but the cladists recognize it as a clade. In sum, I do not support the recognition of polyphyletic taxa, whether they are historical mistakes or current ones.

>>He promotes banishing the birds and mammals from the reptiles because they are "different".>>

Do you have a problem with excluding mammals and birds from Reptilia? You have a problem. You are also in the minority. Besides, if you do not exclude organisms that have evolved disparity from an old taxon, you end up with a single genus for all life on earth because nothing can be deserving of being removed from the old genus. Clearly, if we are going to have more than one genus, more than one family, more than one order, more than one class, and more than one phylum, then we need to remove organism from one genus, family, order, class or phylum and put it in another. The question then, is not whether, but which. Which organisms should be removed from Reptilia and placed in another Class? Most biologists have decided that Mammals and Birds are sufficiently different from Reptiles to be excluded from Reptilia. I happen to agree with them, not because their decision is historical, but because their decision results in a more useful classification than the alternative proffered by some cladists.

>> All reptiles are different. To me, turtles are more divergent from the other amniotes than birds. >>

You are entitled to your opinion of course. Turtles, though quite different morphologically from other reptiles in some ways, are nevertheless morphologically similar to other reptiles in other ways. They are also not physiologically different from most other reptiles.

>> The turtle shell is as different and strange as fur or feathers, but I keep my opinions out of my science. >>

The turtle shell is indeed quite unique among vertebrates. But it is still morphologically simply modified bone and reptilian scales. Fur and feathers, OTOH, are fundamentally different than reptilian scales. Hair grows out of follicles. Feathers are biochemically different from reptilian scales. In fact, feathers are so different from scales that no one has yet figured out how feather evolved.

>> I also think whales and bats are fantastically different from other mammals>>

I, too, agree that whales are quite morphologically disparate. I support classifying whales in the Order Cetacea, instead of classifying them in the same order as the Artiodactyla, even though it has been demonstrated that whales evolved from an artiodactyl and that the closest living relative of whales is the hippopotamus. Nevertheless, whales still retain mammalian characteristics such as lactation and endothermy. Therefore whales are not as different from a typical mammal as mammals are to the reptiles. Do whales deserve to be removed from Mammalia? A vast majority of taxonomists would say no. Bats, although they have achieved flight, are still very much mammal-like in their biology. Hence a vast majority of biologists have not classified bats in a different class from Mammalia. Again, you are probably thinking that everbody else are wrong but you are right.

>>but I don't feel the need to make a taxon out of the non-whale and non-bat mammals to satisfy my ignorant gut feeling that all land mammals seem to be more similar to each other than any of them are to whales or bats.>>

Scientists do not rely on ignorant gut feelings. They rely on data.

>>I allow the whales and bats to remain in the mammal taxon dispite their odd adaptations, and I allow birds to remain in the reptile taxon despite their odd adaptations. >>

We do not need your permission to recognize a Mammalia that includes both bats and whales. We also disagree with your idea that birds should be placed in Reptilia.

>>Seriously, I think this discussion has been enlightening. It shows that some of us can get past our primitive tendency to group things based on superficial similarity.>>

That is a strawman. No one is grouping organisms by superficial similarity, except perhaps those taxonomists who do not critically analyze their characters but rely on superficial similarities. That is why some scientists are dismayed by the cladistic practice of ignoring the goodness of taxonomic characters.

>> We use objective criteria and we accept the results even if the results go against what our middle-school science teachers told us. >>

So far I see no sign that you have any objectivity except for your opening remark. LOL.

>>Bottom line: is phylogeny the pursuit of groups defined by relatedness or perceived similarity?>>

Phylogeny is a science dealing with the evolutionary relationship of living organisms. I think you are confusing phylogeny with classification. Classification is not phylogeny and classification is not science. However, classification must take into account phylogeny. It means that taxa must reflect phylogenetic relationships, but it does not mean that classification is phylogeny and phylogeny only. Classification must be useful because classification exists to serve scientists in their communication. Any classificatory practice that makes communication difficult would therefore be contradictory to the goals of classification. When scientists communicate with each other and refer to reptiles, it is nearly universally understood that they mean a group of basal amniotes that are not endothermic. It is very simple and elegant and it has served us well for centuries. If we include birds in Reptilia and exclude the synapsids and therapsids from Reptilia, then the term reptiles has lost its meaning. Communication is more difficult. Now, when cladists want to communicate with each other, they need to use the term non-avian reptiles. They don't need to do that if they would just leave Aves alone instead of making a mess of their "Reptilia."

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