>>In terms of classifying animals (specifically pythons), I wonder. There were the old days, when people couldn't go and perform a DNA sequence test, yet they still managed to classify animals.

Sure thing. Even Linnaeus produced a pretty good classification, even though he had no idea how evolution worked.

> People like to jump down Hoser's throat (albiet his stance seems bloated), but I fail to see the synonyms in currently accepted taxa. I have never seen a scientific paper or publication that outlines and addresses the various genuses (morelia, python, liasis, etc). Where do these various genuses start to take some accountability? I believe I have a small python book that does a mediocre job at breaking down the various genuses. For liasis, for example, it states that "members of the liasis family do not have prehensile tales" yet my White Lip's tail is damn prehensile. Might sound like a broken record here, but same goes for water pythons I have been affiliated with. I guess my question is; people want validity out of Hoser. If he cannot provide it, then I want validity from the accepted classifications. Just what *does* liasis mean? As far as I'm concerned, my white lip is just that... a white lipped python. Where do we take the critics hats off? Id like to know how classification was dealt with before DNA testing was available.

Before DNA evidence or molecular evidence in general was available, the most powerful technique that was used (and still being used) was comparative anatomy. According to Dollo's principle, superficial similarities are common between convergent characters, but detailed examination of the minutiae of morphological characters can reveal evidence of different ancestry. For example, the forelimb of birds like Archaeopteryx look remarkably similar to the forelimb of some small theropod dinosaurs such as Deinonychus. Both have 3 fingers on their forelimbs and both have the same number of segments on their fingers. Yet, detailed comparative anatomy of available fossils shows that the theropod lineage evolved from a 5 fingered ancestor that had lost the ring and little fingers, while retaining the thumb, index finger and middle fingers. Birds, however, have lost the thumb and little finger, while retaining the index finger, middle finger and ring finger. Theropod dinosaurs therefore have fingers 1-2-3 according to fossil evidence. Bird have fingers 2-3-4 according to developmental evidence. In this case, applying Dollo's principle, birds and theropods are only convergently similar. They did not acquire their similar hands from a common ancestor with 3 fingers. The differences in finger identity is one of the biggest obstacles to the acceptance of the dinosaurian origin of birds. Most ornithologists, therefore, do not believe that birds are descended from a theropod dinosaur.

Enough digression. Python systematics is still in a state of flux because a comprehensive DNA analysis has not been performed on this group. The lesson we learned from morphology is that convergences can sometimes be so remarkable that it may mislead taxonomists into grouping animals that are not closely related. Morphological features are often adaptive. E.g. the prehensile tail can be quite useful for a snake that lives in tress. Therefore many unrelaed snakes can independently evolve this same feature, whereas a tree snake that has returned to the ground may lose all traces of a once prehensile tail. It is often necessary to separate adaptive and non-adaptive characters in one's analysis. The same is true of DNA. The advantage that DNA evidence offers is that there are so many DNA characters that finding neutral characters to analyze relationships can be much easier. Since neutral characters may mutate randomly, there is very little chance of convergence due to adaptation to similar environments. Similarities due to pure chance are much less frequent than convergent similarities as a result of adaptaton to similar enviroments. It is for this reason that Darwinian systematists have relied on neutral characters for grouping relationships since the days of Darwin.

Reference
Feduccia, Alan, Theagarten Lingham-Soliar, and J. Richard Hinchliffe 2005. Do Feathered Dinosaurs Exist? Testing the Hypothesis on Neontological and Paleontological Evidence. JOURNAL OF MORPHOLOGY 266:125¡V166

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