Fossil

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==Transitional Fossils==
 
==Transitional Fossils==
A transitional fossil is one that bridges the evolutionary gap between two organisms. A fossil which is transitional between species A and species B will typically have some features of both. For instance, ''Archaeopteryx'' has both reptilian teeth and avian feathers.
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A transitional fossil is one that bridges the evolutionary gap between two previously discovered organisms. A fossil which is transitional between two species will typically have some features of both, and several features which are developed halfway between the two.
  
[[Creationist]]s like to claim that there is a lack of transitions in the [[gaps in the fossil record|fossil record]], and use this as a claim against evolution.
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[[Creationist]]s claim that there is a lack of transitions in the fossil record in order to argue against evolution, but this is far from the truth. Strictly speaking, all fossils are transitional, since all species are the transition between their ancestors and their descendants. Whether or not we know what they are the transition between does not affect that. But regardless, there are many fossils that definitively link two genuses, orders, and classes. The following is a short list:
  
Creationists also tend to misunderstand the nature of transitionals, and ask questions like "[[what good is half a wing?]]"
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# ''Archaeopteryx'' is an intermediate form between theropod dinosaurs and modern birds. It had teeth and claws like a dinosaur, and avian feathers like a modern bird, large wings but sideways shoulder joints, along with several features common to both.
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# ''Tiktaalik'' is an intermediate form between fish and amphibians. It had gills and scales like a fish, lungs and rib bones and a movable neck like an amphibian, and fish-like fins with limb bones and a fully functional wrist joint with simple fingers.
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# ''Orrorin tugenensis'', ''Ardipithecus kadabba'' and ''ramidus'', ''Australopithecus anamensis'', ''afarensis'', ''africanus'', ''bahrelghazali'', and ''garhi'', ''Kenyanthropus platyops'', ''Paranthropus aethiopicus'', ''boisei'', and ''robustus'', ''Homo habilis'', ''rudolfensis'', ''ergaster'', ''antecessor'', ''cepranensis'', and ''rhodesiensis'', for most of which there have been found several fossils, represent the chain of successive transitions between ''Sahelanthropus tchadensis'' and ''Homo sapiens sapiens'' (modern humans).
  
==Gaps in the Fossil Record==
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==Fossil Record Gaps==
The argument that there are gaps in the fossil record is used extremely often by [[apologists]] and is basically the same as saying that there are no [[transitional fossil]]s. There are several large problems with this argument, however:
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The argument that there are gaps in the fossil record, used by [[apologists]], basically amounts to a claim that there are no transitional forms between the transitional forms we've already discovered.
  
# When [[Darwin]]'s ''[[The Origin of Species]]'' was first published the fossil record was very sparse , and thus the size of the gaps it contained (i.e., between older species and their supposed descendants) was a problem for the theory of descent from a common ancestor. However, as the years passed scientists found more and more fossils, some of which "filled in" the gaps, thus decreasing the "jumps" required to move from one species to another. Nowadays gaps do still exist, and even though there are large gaps remaining, in many places the gaps are comparatively very small.  It's not logical to assume that the gaps that exist nowadays will never be filled.
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This argument
# In reality, there's almost no way to convince a [[creationist]] that transitional fossils exist.  For example, suppose scientists don't know how one animal evolved into another.  Creationists then tout this gap (the gap between fossil A and fossil B) as proof that there are no transitional fossils.  However, when a transition (fossil C) ''is'' discovered between the two, the creationist will simply say that there are now two gaps, one between fossil A and fossil C and one between fossil C and fossil B. In other words, the more transitions are discovered, the more gaps creationists posit.
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# misunderstands what constitutes a transitional feature.
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# ignores the large number of fossils found.
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# denies the transitions those fossils represent.
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# is ignorant of the fossilization process.
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# creates an expectation of accuracy far beyond what is necessary to illustrate transition.
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# dismisses definitive examples of transitional forms, focusing on the ones that remain undiscovered.
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# theoretically [[moving the goalposts|moves the goalposts]] every time a "gap" is filled, as each discovery of a transitional form creates two new gaps.
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# is profoundly ignorant of the mechanisms of evolution itself.
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[[Category:Science]]
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[[Category:Evolution]]

Revision as of 13:21, 12 March 2012

Fossils are the remains of organisms from the distant past embedded and preserved in the earth's crust. Fossils may be any sort of organism, from a single-celled bacteria to a tree leaf to a dinosaur, and may be anywhere from ten thousand to several billion years old. They usually consist of parts of the organism which were mineralized during the organism's lifetime, such as bones and exoskeletons.

Transitional Fossils

A transitional fossil is one that bridges the evolutionary gap between two previously discovered organisms. A fossil which is transitional between two species will typically have some features of both, and several features which are developed halfway between the two.

Creationists claim that there is a lack of transitions in the fossil record in order to argue against evolution, but this is far from the truth. Strictly speaking, all fossils are transitional, since all species are the transition between their ancestors and their descendants. Whether or not we know what they are the transition between does not affect that. But regardless, there are many fossils that definitively link two genuses, orders, and classes. The following is a short list:

  1. Archaeopteryx is an intermediate form between theropod dinosaurs and modern birds. It had teeth and claws like a dinosaur, and avian feathers like a modern bird, large wings but sideways shoulder joints, along with several features common to both.
  2. Tiktaalik is an intermediate form between fish and amphibians. It had gills and scales like a fish, lungs and rib bones and a movable neck like an amphibian, and fish-like fins with limb bones and a fully functional wrist joint with simple fingers.
  3. Orrorin tugenensis, Ardipithecus kadabba and ramidus, Australopithecus anamensis, afarensis, africanus, bahrelghazali, and garhi, Kenyanthropus platyops, Paranthropus aethiopicus, boisei, and robustus, Homo habilis, rudolfensis, ergaster, antecessor, cepranensis, and rhodesiensis, for most of which there have been found several fossils, represent the chain of successive transitions between Sahelanthropus tchadensis and Homo sapiens sapiens (modern humans).

Fossil Record Gaps

The argument that there are gaps in the fossil record, used by apologists, basically amounts to a claim that there are no transitional forms between the transitional forms we've already discovered.

This argument

  1. misunderstands what constitutes a transitional feature.
  2. ignores the large number of fossils found.
  3. denies the transitions those fossils represent.
  4. is ignorant of the fossilization process.
  5. creates an expectation of accuracy far beyond what is necessary to illustrate transition.
  6. dismisses definitive examples of transitional forms, focusing on the ones that remain undiscovered.
  7. theoretically moves the goalposts every time a "gap" is filled, as each discovery of a transitional form creates two new gaps.
  8. is profoundly ignorant of the mechanisms of evolution itself.
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