Are all fossils “transitional”? A test rant.

All over the net I see people trying to defend evolution from the attacks of antievolutionists which is good. However when they do so using false or inaccurate arguments that is not so good. For example one of my pet peeves is a particular argument that I’ve seen commonly used to rebut antievolutionist claims that there is a lack of “transitional” forms in the fossil record which often goes something like this:

“You don’t know what you’re talking about, all fossils are transitional.”

Unfortunately this is simply not true. Not all individuals reproduce; nor do all species give rise to new species. In fact many (if not most) lineages in the history of life have led to dead ends. Think about it, if a fossil represents a species which did not give rise to new species, what is it transitioning to?

Of course part of the problem is the use of term “transitional fossil” since the word transitional implies that there is some certainty about specific lineages which is actually rarely the case in paleontology.

It is better to talk about “intermediate fossils” since this refers to morphological characters (facts) rather than hypothetical lineages.

For example Archaeopteryx is undeniably intermediate in form between dinosaurs and birds being a mixture of both dinosaurian and avian (and some in between) characters, this is a fact. The question as to whether or not the genus Archaeopteryx is itself ancestral to later birds would be a hypothesis which is 1) very difficult to test and 2) not one that all paleontologists who work on dinosaurs/birds necessarily agree upon.

So please, for the sake of my sanity (and for scientific accuracy), spread the word to stop claiming that all fossils are “transitional” and maybe encourage the use of the term “intermediate” instead.

End rant.

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8 thoughts on “Are all fossils “transitional”? A test rant.

  1. Pingback: Threads from Henry’s Web » Troy Britain Has a New Blog

  2. I sometimes used the two terms interchangeably, always with the proviso that ‘intermediate’ or ‘transitional’ refers to the form, and does not necessarily imply a direct lineal ancestor/descendant relationship. Although I see where that can still be confusing. What do you think of the argument I’ve occasionally heard that ‘intermediate’ is still somewhat deceptive since it can imply that the form is in the middle, when in reality it may be closer to one or the other endpoint, and that yet another word like ‘interposed’ may be more appropriate?

    BTW, good luck on the new blog, and great shirt! Hope your wife is feeling better.

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  3. Dave S.: What do you think of the argument I’ve occasionally heard that ‘intermediate’ is still somewhat deceptive since it can imply that the form is in the middle, when in reality it may be closer to one or the other endpoint, and that yet another word like ‘interposed’ may be more appropriate?

    Whatever is used will probably take some explaining. For example it needs to be pointed out more often that intermediate fossils are not going to be intermediate in all characters, rather they are mixtures of intermediate characters and mosaics of primitive and advanced traits, with characters from both the parent group and the daughter group. Archaeopteryx being a classic example. While it had some intermediate characters it was also a mix of “dinosaurian” characteristics and “avian” characters. Of course the distinction between what constitutes dinosaurian and avian has become more clouded with the introduction of so much new material from China. Oh the horror of having too many intermediate types!

    BTW, good luck on the new blog, and great shirt! Hope your wife is feeling better.

    Thanks and thanks.

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  4. While you are at it, explain “primitive” and “advanced” traits. Since it is also often said that later is more advanced than earlier assuming some kind of “direction”.

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  5. Not all individuals reproduce? In the grand scheme of things, this is not an issue. Any fossil form that does not reproduce will either be just like its parents, or a transitional form with a history. Even a dead end species has a history to come from. This posts’ argument fails.

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  6. It’s almost like you don’t quite grasp what is meant by “evolution occurs within populations, not individuals”. All populations are in a constant state of evolving. Evolution is the change in allele frequency within a population over time. The allele frequency of the population changes with each new addition or subtraction from the population unless the population is inbred to the point that even the humans aboard the fictional Noah’s Ark had more genetic diversity. The fact that the population may face extinction prior to speciation is irrelevant. Therefore all fossils represent transitional forms, it’s complete nonsense to say otherwise. For someone who accepts the fact of evolution to deny this fact shows that this person is at least intelligent enough to accept that experts in a field should be trusted over mythology but that the person doesn’t really understand the mathematical implications of what “change in allele frequency” actually implies.

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