That's not a Missing Link! - the vocabulary of "Intermediate Forms"


The nuance I would add is that biology and inheritance are a bit messy. We would not expect phylogenies based on DNA and morphology (i.e. morpho=shape, how a species is shaped) to exactly match one another if evolution is absolutely true due to mechanisms such as incomplete lineage sorting, homoplasies, and the number of species we have to test these hypotheses. What scientists look for is the phylogenetic signal which rises above the messy noise of biological inheritance. Like almost everything in biological research, the statistical significance of the match between phylogenies is what counts. Talkorigins actually has a half way decent primer on the basics of the statistical testing.

(T J Runyon) #22

Let’s be clear about something. No older tetrapod fossils have been discovered. You have footprints. Which are pretty controversial. I’m still not sure. And tiktaalik was never presented as a transitional form (direct ancestor). Tiktaalik is still an intermediate form because it has a mixture of characteristics between two groups. Even if it came after tetrapods. Descendants can hold onto traits of their ancestors. So it can tell us how the transition took place.
Note: saw where this was already discussed above. Didn’t read the thread until after I posted

(George Brooks) #23


I challenge you to produce a peer-reviewed article that defends your position.

There are plenty of fossils of all kinds in the rocks. I can’t even begin to interpret how you came to your conclusion, or from which Denomination Against Knowledge you may have heard such a thing.

(T J Runyon) #24

Ummm, you may have seriously misunderstood me. What position do you think I’m defending?

(T J Runyon) #25

I’m fully aware there are Devonian tetrapods… I was responding to Marty’s claims that pre Tiktaalik tetrapods have been found. But those are just trace fossils (footprints in this case) and these are relatively controversial

(T J Runyon) #26

This is pretty relevant to the tiktaalik conversation. It predates the Poland tracks

(George Brooks) #27


This is what I read in your posting:

“Let’s be clear about something. No older tetrapod fossils have been discovered.”

I think I missed the part about no tetrapod fossil is “older”. I missed that … and without going any further, I had assumed I had a YEC running around with scissors… My apologies…


Although @gbrooks9 may disagree, I consider transitional and intermediate to be synonyms. They both mean that a fossil has a mixture of features from two other taxa, and neither implies anything about ancestry. Direct ancestry and transitional are two different things. Even the wiki definition for transitional fossil says the same thing:

A transitional fossil is any fossilized remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group.[1] This is especially important where the descendant group is sharply differentiated by gross anatomy and mode of living from the ancestral group. These fossils serve as a reminder that taxonomic divisions are human constructs that have been imposed in hindsight on a continuum of variation. Because of the incompleteness of the fossil record, there is usually no way to know exactly how close a transitional fossil is to the point of divergence. Therefore, it cannot be assumed that transitional fossils are direct ancestors of more recent groups, though they are frequently used as models for such ancestors.[2]

(George Brooks) #29


They are synonyms… but so were the words “alchemy” and “chemistry”. Over time, words usage evolves to reduce confusion and unintended interpretations.

“Intermediate forms” and “Intermediate fossils” are becoming the “best practice” terms to avoid the more egregious abuses, and to help steer the media into the correct context.

@T.j_Runyon’s sentence below benefits from his use of “intermediate”:

(T J Runyon) #30

No worries! And for future reference for future dialogues I accept evolutionary theory and am a student in evolutionary biology. Interests in Miocene apes, the origin of Anthropoids, evolution of the primate hand and dentition, the role of cultural niche construction in human evolution and Homo Erectus.