The Definition and Description of a "Transitional"

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Don't those characteristics need to be "defining" characteristics of the taxa? So things that lots have in common don't count?

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When looking at two taxa you look for characteristics that are easily fossilized (such as bones/feathers) and are distinctly and objectively different between the taxa.One example that I like to go with is the reptillian and mammalian middle ears. These two systems are objectively different, they are different both in structure and what bones make them up. We should then find fossils that are in transition between the two states, and we do.Another example (staying with mammals and reptiles) is the teeth. Mammals have very specialized teeth (canines, molors, incisors) while reptiles have teeth that are uniform in shape (conical). We should expect to see fossils that have a mixture of these two types of teeth.These are just a couple of examples, but such differences can be found between almost any taxa, especially at the level of reptiles and mammals. However, we wouldn't expect every feature or characteristic to be half way. Rather, you expect to see a mosaic, with some features nearing complete cross over while other features lag behind. As mark24 pointed out, we look for fossil species that have characteristics of both, or characteristics that are in transition between the two states.

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I will as a creationist try to deal with this.
But first you must allow me something.
We Don't believe there are transitionals so our defining what they are or look like is,ah,unnatural.

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Creationists claim that that evolutionists have not FOUND any transitional fossils. Evolutionists claim that they have, and they define in detail why it is a transitional fossil. Creationist claim that it isn't transitional because it doens't jive with their Bible, a very subjective and empty reason. Instead of giving concrete, objective reasons for rejecting these fossils, creationists instead claim that they SHOULDN'T exist, which, I guess, allows them to ignore their very exisitence. IOW, creationists are scared so they refuse to look at them or define what a transitional fossil should look like.

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The creature must be suitable to survive in its envirorment. And yet be an ancester of a body type that was sucessful in another envirorment. HMMM

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This is a very good start. The other possibility may be that a transitional species could live successfully in both environments. For instance, a species that is able to live both in water and on land.One such species alive today is the mudskipper. Here is a description from iiNet | naked dsl - broadband - adsl - phone - voip: Even today we can see species that are in transition from aquatic to terrestrial environments. This is exactly what we would expect to see in the fossil record. And we do: The above is a painting of the fossil species Acanthostega. It had both internal lungs and external gills. It's limbs can be classified as both fins and legs. It's head is obviously fishlike, as is it's tail. This is a perfect example of what we would expect from a transitional species, a species that it is adapted to two different environments.This species (Pederpes) is also a transitional, and it displays bone structures that are preserved in tetrapodian terrestrial species today, including a femur, tibia, ulna, radius, humerus, etc. This is exactly what we would expect to find, since evolution builds on previous body types instead of creating new structures all at once. Does this fit what you would call transitional?This message has been edited by Loudmouth, 07-26-2004 02:30 PM{Fixed large quote box - AM}This message has been edited by Adminnemooseus, 07-26-2004 03:01 PM

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Let me see if I got this. You're saying then that the transitional species has more information than the present one because it went from being able to live in both enviroments (land - water) to living in only one. Hmmm wasn't information supposed to increase. A cat can walk, jump, swim and climb just like the mudskipper. So i guess a cat is also in a transitional state.

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Information has nothing to do with it. A transitional form displays characteristics of two different taxonomic categories, in this case fish and amphibians.

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Yes but in order to believe you I need to see the original fossil and not a drawing. I can draw a picture of God from what I read in the bible but will it be enough to convince you of his existence.

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If I show you the real fossil will you accept it as a transitional form?

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Not very likely, based on his past behavior, but you can try if you want.

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Jazz is one of the more congenial creationists around here, so don't jump to conclusions. What I want to avoid is the creationist run-around, which goes as follows:Creo: "There are no transitional forms."Evo: "Yes there are, look at this drawing of a fossil."Creo: "How can I trust a drawing, Haeckal faked his drawings."Evo: "Here is the actual fossil."Creo: "That isn't a real transitional, it is just a different created kind."In the end, the accuracy of the drawing is never really in question, just the definition of what the fossil is. I felt like skipping the second response and go right to the issue at hand.

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If we define transitional in this way, then there is truly no organism on the planet (extant or extinct) that could not be considered a transitional, because every organism, no matter how exotic, will have characteristics that are in some way similar to organisms of other taxa.

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This is false. It is true that every organism is a transitional, but this is because evolution is the best theory. A non-transitional would be a bat with feathers or a whale with gills. Not only does a transitional need to have characteristics that bridge two taxonomic groups, but that bridge must be along evolutionary lines. The fact that these types of transitionals (ie feathered bats and gilled whales) do not exist is a testament to the accuracy of the theory of evolution. What would prevent God from creating bats with feathers or whales with gills? Nothing. However, these orgaisms would falsify the theory of evolution.

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I think you are overlooking some key points. As a creationist myself, I accept that transitionals did and do exist. The limited number of animals on the Ark subsequently evolved into many of the land animals we see today. Most creationists, whether they know it or not, seem to take this perspective. It would seem that the difference between creation and evolution does not lie in whether or not transitionals existed to bridge organisms to common ancestors. On the contrary, the fundamental difference is that creationists: (a) deny that transitionals linked all major animals groups to a single common ancestor (i.e., they instead propose the existence of numerous common ancestors in the form of kinds); and (b) deny that the stratigraphical sequences of fossils in the geologic record are attributable to evolutionary change (i.e., they propose that the fossil record is the result of non-evolutionary mechanisms).

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In my opinion, the usual "litmus test" that creationists apply to the "created kinds" is a very simple one. Any amount of evolution judged to be capable of producing man from ape is considered false. The litmus test is really the ape-man test.The reality of the matter is that we have very nice transitional fossils for the transition between reptile and mammal, land mammal and whale, ape-like ancestor and man, etc. The supposed small steps in evolution described by creationists are actually outnumbered by the larger number of fossils supporting larger changes.

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It soon becomes clear that modern evolutionary theorists have turned a massive set of seemingly contradictory data points into supporting evidence. And all of this falls quite nicely into any definition of transitional that we conjure up here. Those fossils that fit the definition support evolutionary theory, while those fossils that do not fit (or contradict) the definition can be explained away by convergence and therefore indirectly . . . support evolution. How convenient.

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This is totally false. You are forgetting about the examples I listed that could, in fact, falsify evolution. Feathered bats and gilled whales could not be explained through evolutionary theory given the fossil record that we have. What prevented God from creating such creatures? Nothing.Also, you are forgetting about the second realm of evidence within evolution, DNA. Let's take a specific example. Are you familiar with the tasmanian wolf? It is a marsupial carnivore that, outwardly, closely resembles the north american wolf. According to the fossil record the NA wolf and the tasmanian wolf are examples of convergent evolution. Given that DNA reflects one's ancestory despite outward appearances, the tasmanian wolf should be distantly related to NA wolves and more closely related to other animals, such as kangaroos and wombats, on the mainland of Australia and Tasmania. Guess what the data says? The NA wolf is as closely related to the tasmanian wolf as they are to humans. The closest DNA match to tasmanian wolves are other marsupials, which look nothing like a wolf, in Australia and Tasmania. A tasmanian wolf, despite outward appearances, is more closely related to kangaroos than to the NA wolf. If a creator made all of these species separately we would expect, from outward appearances, the tasmanian and NA wolf would be the closest relatives. This is simply not true. Therefore, convergent evolution is both supported and logical.

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I am still unclear as to how to define transitional in such a way as to provide a possibility for falsification.

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Feathered bats and gilled whales are perfect examples of transitionals that would falsify evolution. For evolution to be true there must be a nested hierarchy. That is, each group of species must fit inside a larger description of a larger group. For instance, humans are part of the great apes. Great apes and monkeys fit into the larger group called primates. Primates and ungulates fit into a larger group called placental mammals. This is what is called a nested hierarchy where each group nests inside of a larger group.A transitional that does not fit this pattern is a potential falsification of evolution. That is why a mammal sharing bird characteristics is a falsification. The fact that we don't see these types of transitionals is a testament to the accuracy of evolution, not it's inability to be falsified.

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In any case, whatever definition of transitional that modern evolutionary theorists have decided upon, they are less than shy in admitting their virtual non-existence (except to the general public, of course). A brief look at the evolutionary literature will make this point evident, as Carroll and Stahl (see above) in their paleontology books admitted the failure of the fossil record to demonstrate morphological/physiological change in 239 separate paragraphs.

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This glosses over the fact that we do have transitional fossils that bridge large gaps. While we may not have ALL of the transitional fossils, we do have enough to have great confidence in the theory of evolution. This is the very attitude that I was speaking of before, about creationists being afraid to face the facts. Creationists would rather talk about the gaps than fess up to the gaps that have been filled. Just one transitional fossil between two divergent taxa (ie mammals and reptiles) falsifies special creation. According to creationism, there should not be a string of transitionals that have both mammalian and reptillian characteristics. According to creationist, a feathered bat or a gilled whale should have the same chances of being created as a transitional between reptiles and mammals. Why don't we see feathered bats or gilled whales?

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Can you post a link to this/these "very nice" transitional fossil(s) for ape-like ancestor and man?

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Here is a picture of the most important transitional fossil skulls. Key:
(A) Pan troglodytes, chimpanzee, modern
(B) Australopithecus africanus, STS 5, 2.6 My
(C) Australopithecus africanus, STS 71, 2.5 My
(D) Homo habilis, KNM-ER 1813, 1.9 My
(E) Homo habilis, OH24, 1.8 My
(F) Homo rudolfensis, KNM-ER 1470, 1.8 My
(G) Homo erectus, Dmanisi cranium D2700, 1.75 My
(H) Homo ergaster (early H. erectus), KNM-ER 3733, 1.75 My
(I) Homo heidelbergensis, "Rhodesia man," 300,000 - 125,000 y
(J) Homo sapiens neanderthalensis, La Ferrassie 1, 70,000 y
(K) Homo sapiens neanderthalensis, La Chappelle-aux-Saints, 60,000 y
(L) Homo sapiens neanderthalensis, Le Moustier, 45,000 y
(M) Homo sapiens sapiens, Cro-Magnon I, 30,000 y
(N) Homo sapiens sapiens, modernAdditional info:
29+ Evidences for Macroevolution: Part 1Fossil Hominids: the evidence for human evolution (this page gives the fossil species, creationist arguments, and rebutals to creationists; a nice rounded view of the whole issue).

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What I see here are distinctions made on the basis of height, brain size, teeth size, build, etc.

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Are these distinctions not simply possible between different human beings?

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No human falls within the range given for earlier hominids, especially brain size. I believe that some human characteristics, but not all, fall into the range of H. erectus. Also, look at the photos above and focus on the brain case. You will notice that humans obviously have bigger craniums than the earlier fossils.This message has been edited by Loudmouth, 12-15-2004 04:28 PMThis message has been edited by Loudmouth, 12-15-2004 04:30 PM

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But don't human heads vary, sometimes greatly, in size from one to another?

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Human skulls do vary in size, but not enough for them to fall in the range of some of these hominid fossils. The graph below illustrates the human range (the two ranges on the left hand side of the graph) and the sizes of skulls from prominent hominid fossils. The symbols are a difficult to pick out so I had to go back to the original paper in .pdf format (found here). I will try and relate the symbols to the data starting on the right hand side of the graph.As you can see, A. afarensis and A. africanus fall well outside normal ranges for living humans, as do A. robustus and A. boisei. Moving from right to left, the squares with plus signs represent H. habilis, the first species in the genera Homo. This species falls well outside the human range as well, but is slightly bigger than the Astralopithecus genera. The next grouping to the left is H. erectus. Some of the fossils from this species falls within the human range, but most fall below the human range. Next, we have archaic H. sapien, early modern H. sapien, and neanderthals which all fall within the modern H. sapien range. This graph shows a progression of brain size through time, and as someone else mentions above, through geologic depth as well.So to answer your other question, "Are human skulls sometimes mistaken for ape skulls" the answer would be an emphatic NO. From the picture I listed above (the transitional fossil picture) would you ever confuse the chimp skull with a human skull? I sure wouldn't, nor would any paleontologist. Also, there are other features besides the skulls that differentiate humans from early hominids and apes, such as the pelvic girdle and dentation.

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Is it possible for a "transitional" skull to be very simply a deformed human or ape skull? Aren't some humans born with gross deformities, sometimes in many features?

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Anything is possible. But as Jazzns says in the post above, why would we only find these deformities as a function of geologic depth? Why don't we find normal, modern human/ape skulls at the same depth? There is no reason, other than in an attempt to ignore the data, to propose that these skulls are due to birth defects. This also ignores the fact that the skull is only one aspect that is transitional. Don't forget that the teeth, pelvic girdle, arm length to body ratios, etc. all point to these fossils as being transitional as well. The skull is just one piece of evidence.