Feb 05 2013

Transition Denial and Feathered Dinosaurs

There are a few areas of evolutionary biology that particularly fascinate me, partly because they represent such a dramatic example of large-scale (macro) evolutionary change. The evolution of whales from terrestrial mammals and of humans from ape ancestors are two of my favorites. But perhaps more dramatic still is the evolution of birds from theropod dinosaurs.

Each discovery of a feathered dinosaur or bird ancestor is a lance straight through the heart of creationist denial of evolution. I have to admit it’s fun to watch prominent creationists squirm when confronted with such clear evidence of transitional forms and evolutionary change – not that they flinch in their denial, but their protestations do become increasingly shrill and desperate.

Welcome Eosinopteryx brevipenna, the latest feathered dinosaur discovered in China. This little guy had feathers, although described as “reduced plumage”, stubby wings (and so was probably flightless), a bony tail, teeth, and clawed fingers. It also lacked many modern bird features, such as bony features that would have allowed for full flapping flight. Its feet were clearly adapted for running.

This creature was not simply a flightless bird, like an ostrich, it was a feathered dinosaur. Minus the feather impressions, in fact, it would look like a typical small theropod dinosaur.

What is increasingly clear from the fossil evidence is that paraves (bird-like theropod dinosaurs) was a diverse and large group, with one path leading to modern birds. It is a beautiful evolutionary story – a bushy tree of adaptive radiation with only one branch surviving into modern times as a definable group – birds.

A century and a half ago biologists hypothesized that birds may have evolved from dinosaurs, a theory that received its first confirming evidence with the discovery of Archaeopteryx in 1860. In the last 30 years paleontologists have discovered numerous species of feathered dinosaurs filling in the morphological space between birds and dinosaurs. They have also discovered that many known theropods, like velociraptor, probably had feathers also, and they have found transitional feathers. It is difficult to imaging a more stunning, thorough, and definitive confirmation of a scientific theory.

All the time creationists have been in a state of increasingly absurd denial. This latest find is no exception. Ken Ham of Answers in Genesis writes:

Now, one headline described the fossil as “almost birdlike,” and the authors of the report in Nature Communications note many features the fossil shares with living birds, particularly those that live on the ground.  In fact, Dr. Elizabeth Mitchell and Dr. David Menton (AiG–U.S.) both examined the photos of the fossil and the criteria the authors used in classifying the fossil as a dinosaur. They agreed that it is a bird, not a feathered dinosaur.

This is a typical creationist tactic – take a continuum in the fossil record, like dinosaurs to birds, and simply claim that any fossil along that continuum belongs to either one end or the other – in this case, is either a dinosaur or a bird. It doesn’t matter that this creature has a pretty even mix of bird and dinosaur features.

Ham continues:

The report claimed that the fossil is between 153 and 165 million years old. Not only that, but the researchers have based all their findings on the assumption that birds are just highly evolved dinosaurs. You see, their whole system of thought is so rooted in evolutionary ideas—like common ancestry—that they can’t see the problems with their own analyses.

Ham does not describe what the alleged problems are. This is another typical creationist tactic, arguing that scientists assume evolution when they analyze fossils, and therefore the fossils are not evidence of evolution. First, these two things are not mutually exclusive. Evolution is proven science, so it is reasonable to take it as a premise. But that does not mean that new evidence interpreted in the context of evolution is not also evidence itself that evolution is correct (as is the case here).

The detailed analysis of Eosinopteryx is anatomical and is independent of evolutionary theory. It has a bony tail and teeth – no matter what you think about the implications of these facts.

I also have to marvel at the irony of Ham accusing scientists of being so “rooted” is a way of thought that they cannot see the obvious (your irony meter definitely needs to go to 11). In fact the next line is:

The fossil record doesn’t reveal any kind of dinosaur-to-bird evolution—and it certainly does not show  a molecules-to-man evolution. We have no proof of transitional forms, and we won’t. God’s Word says clearly that He created animals and plants according to their kinds (Genesis 1).

I see, we will never have proof of transitional forms because the bible tells us so. In other words – no matter how much  stunning and incontrovertible evidence we discover of transitional forms, believers in Ham’s version of reality simply cannot see it – must not see it.

What Eosinopteryx proves is that dedicated creationists will not acknowledge transitional forms no matter how solid the proof. If Eosinopteryx is not a transitional form – then what is? What could possibly qualify as a transitional form in Ham’s eyes. Perhaps he adheres to the crocoduck school of creationist thought – only an impossible chimera (something not predicted by evolutionary theory) would be evidence of evolution. That’s a nice way to rig the game.

Ham links to an allegedly more detailed analysis by Elizabeth Mitchell, but her analysis contains almost no new details, and is just more wordy. She discusses the report in more detail, and her only counter point is the same claim that scientists assume evolution in their classification scheme. She thinks the fossil is a bird, and does not address the teeth, bony tail, clawed fingers, and other obvious dinosaur features.

Conclusion

Scientists have uncovered increasing examples of feathered dinosaurs and creatures that are morphologically transitional from dinosaurs to birds. This is not a straight line or “ladder”, but a diverse bush. The evidence is now overwhelming. Creationists are reacting with the intellectual equivalent of sticking their fingers in their ears and droning “I can’t hear you.” They maintain their increasingly bizarre claim that there are no transitional fossils (because there just can’t be).

This is clear evidence of both the power of evolutionary theory and the intellectual bankruptcy of creationism.

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