Dorudon atrox picture courtesy of Mark Uhen
WHY CREATIONISM
IS WRONG: TRANSITIONS
Moderate Creationists,or
anti-Darwinists claim that there are no 'transitional' fossils.
What do they mean? What
are 'transitional forms' that Darwin's theory requires to be found in the fossil record
and what else do Creationists mean? In some cases it is simply the change of one group of
animals from one higher-level taxonomic group to another, like between the classes
Reptilia and Aves, reptiles to birds.
Whales used to be the
favourite example of all anti-Darwinists, because a clear fossil sequence from land-going
to marine whales was unknown. However since 1979 a clear sequence of fossil whales that
bridge the gap has been unearthed, covering the period between 53 million years ago [53
mya] to 40 mya, when the first fully marine whales are found.
The illustration above is one
such species in the sequence. Dorudon atrox is a fully aquatic animal,but it
retains a small set of hindlegs indicating its terrestrial origins, like other whales from
its day, some 40 mya. A species like it became the ancestor of modern whales - toothed
whales [Odontocetes] and baleen whales,[ Mysticetes], about 35mya.
Now that the fossil gap for
whales is filled the Creationists have few high-profile animal groups to be sceptical
about their fossils. Often their literature is still full of claims that 'major
transitions' still have no clear fossil record. Let's look at those 'major transitions' in
some detail...
MUCH is yet to be learnt about all these
transitions, since we have relatively few fossils for some transitions. BUT few is NOT
zero, as the anti-Darwinians claim. And more are found all the time. They are very clear
evidence for what Creationists call MACROEVOLUTION - a term that needs explaining because
it has been the source of much confusion.
MACROEVOLUTION: For evolutionary biologists this means evolution of
one species into another [or several], or at higher levels of taxonomy. Thus a species of
fruit-fly diversifying into dozens in the Hawaiian islands is Macroevolution.
Creationists frequently claim that
evolutionists themselves have claimed that there are no 'transitional forms' and so no
'macroevolution'.
What they have failed to realise, or
perhaps communicate to their target audiences, is the missing transitional forms are forms
between two related species - say between the various species of African zebra. And it's
true, such transitions are rarely found.
Why? Because the fossil record is not
perfect and neither are our collections from it. To fully document a transition between a
parent and descendent species requires hundreds or thousands of fossils to be collected
over a continuous time span and a broad area. Most fossil species however are not so well
known, and they often require laborious excavation and chancey discovery to be known in
detail. Only small animals that leave abundant fossils can be useful in documenting
transitions.
Over the past twenty years palaeontologists
have dug up many, many examples of transitions between species. They have done this to
study, in detail, the process of evolution and species change. Is species change GRADUAL
and affecting the species as a whole, or is it SUDDEN, starting with a small out-lying
population that changes and then competes with its parent species? These questions
palaeontologists set out to answer 30 years ago.
BOTH happen is the answer - slow and
gradual, and sudden and dramatic... but both findings support Macroevolution's reality.
Another source of confusion is the concept 'MOSAIC EVOLUTION'. What it simply means is that species intermediate between two
higher-taxonomic levels - say between reptiles and mammals - will show a set of features
that are a mosaic of the two, ancestral and descended.
Mammal-like reptiles, the Therapsids, often
show reptilian and also mammalian features quite distinctly. A striking example of this
mosaic pattern can be seen in several advanced CYNODONT groups that have both reptilian
and mammalian jaw-joints. Archaeopteryx is another mosaic, possessing several avian
features - chiefly its flight adaptations - and many reptilian features [eg. long-bony
tail, claws on its arms, small breast-bone, teeth] that later bird groups lose bit by bit.
HERE'S a discussion on the LITERAL
understanding of Genesis 1 - 11...
GENESIS
Other puzzles of Evolution:
THE CAMBRIAN EXPLOSION: A PUZZLE FOR
DARWIN. CAMBRIAN
HOW CAN A RANDOM PROCESS CREATE COMPLEXITY? RANDOM
LIFE'S ORIGIN: THE ULTIMATE MYSTERY OF
BIOLOGY. ABIOGENESIS
Fossils show replacement through time. More
modern species appear the closer in time we are to the present - hard to explain in a
Creation scenario. Here's an exploration of the data that Creationists want to forget... FISH
WHAT IS
EVOLUTION?
Who Is
God?
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