Jul 28 2011

Some Bad Reporting about Archaeopteryx

Archaeopteryx lithographic is one of my favorite fossils. The Berlin specimen is practically a work of art. It is also a classic example of a transitional species, with a compelling blend of avian and dinosaur features. As much as it’s possible for a single fossil to be so, Archaeopteryx is a smoking gun of the evolution of birds from theropod dinosaurs.

It is also a much maligned fossil. Creationists have attacked it in every way imaginable, calling it a fraud, and ironically at times saying it’s just a dinosaur, and at others saying it’s just a bird.

But perhaps the most common misconception about the fossil, and about transitional fossils in general, is that their value as evidence for an evolutionary connection is dependent on their being a literal ancestor of the descendant group (in this case, birds). In other words, Archaeopteryx’s value as a transitional fossil is dependent on it being on the direct line that led to birds. This, however, is almost certainly not the case, and is also mostly irrelevant.

A new computer analysis of feathered dinosaur species suggests that Archaeopteryx should be placed with the feathered theropods and not in the proto-avian line. This is not surprising, and does nothing to diminish the value of Archaeopteryx as a fossil. But this fact is being reported as if it somehow destroys Archaeopteryx as a transitional fossil. One headline declares: “Charles Darwin may have just lost Evolution Exhibit A, otherwise known as Archaeopteryx.” The article states:

It turns out Archaeopteryx, the iconic 150 million year old “original bird”, is probably just another dino with feathers, of which there are many, the researchers said.

It is hard to imagine a tougher fall from evolutionary grace.

The implication is as I stated above – unless Archaeopteryx is the “original bird” it has fallen as a transitional fossil. Rubbish. The article does a great disservice to the understanding of evolution and fossil evidence.

The problem with this reasoning is that we almost never find specimens that are literal direct ancestors to extant species – a representative of the small population that directly gave rise to the new species. The chances of finding a fossil of such a transitional population is exceedingly small. Evolution is also not a linear process but a messy branching bushy process. Now that we understand that, we expect to finds lots of cousins and uncles, and only rarely actual parents and grandparents. We are finding random samples from somewhere in the bush of variation, but unlikely to be directly on the tiny branch that led to the descendant group.

It is helpful to know how close to that direct line a fossil species is. Most specimens are “side branches,” but can still be very close to the branch we are interested in.

When it comes to the evolution of birds from dinosaurs, prior to the discovery of Archaeopteryx we had dinosaurs fossils and living birds – with a pretty huge gulf in between. Archaeopteryx filled that gulf with a species that is just about half dinosaur and half bird. It is a transitional species – it is morphologically transitional and it does represent a group of animals that exist evolutionarily between dinosaurs and birds.

We now have evidence from multiple fossils that there was a large group of feathered dinosaurs branching out in many directions during this time (and apparently, mostly in what is now China). Only one path meandering through this forest of feathered dinosaurs actually led to modern birds. It would be amazing if Archaeopteryx, the first such specimen found, lay on this path rather than some side path. But it still occupies this evolutionary space between dinosaurs and birds.

The article also quotes professor Lawrence Witmer as saying:

“Perhaps the time has come to finally accept that Archaeopteryx was just another small, feathered, bird-like theropod fluttering around in the Jurassic.”

I disagree with this characterization. Archaeopteryx could fly – that makes it very bird-like; much more so than velociraptor, which had feathers but not flight feathers, and could not fly. Archaepteryx may, cladistically, be in the theropod clade rather than the bird clade, but it branched off pretty far down the line to birds.

I guess it’s possible that flight evolved independently in Archaeopteryx from the line that led to birds. It’s possible that small feathered theropods independently evolved flight multiple times. I don’t think that’s what this new computer analysis is saying, however. Even still – that would not diminish Archaeopteryx as a representative (the first discovered) of the larger group of theropods that was evolving feathers and flight.

I have followed the discovery of the many feathered dinosaurs over the last 20 or so years with great interest. This is a fascinating and beautiful group of animals, and is a stunning vindication of evolutionary theory. This is just what we would expect must exist if dinosaurs evolved into birds – a large branching group of transitional species with some dino and some bird characteristics.

Creationists, however, are likely to latch onto the terrible reporting about this new analysis as if it destroys one of the “icons of evolution.” The fact that Darwin himself referred to Archaeopteryx as a transitional species is all the better, because then they get to say that “Darwin was wrong” about something. That is how creationists twist new fossil evidence for evolution into an argument against evolution. This is in line with the broader denialist strategy of focusing on changes or disagreements with the small details (where exactly to place Archaeopteryx in the feathered-dino to avian bush) as if it calls into question the large picture of evolution.

The article relies on a couple of cheap shots in order to sensationalize this story. Good science reporting, however, uses new studies or information in order to inform the reader about the broader relevant concepts – how to put the information into context.

10 responses so far

10 thoughts on “Some Bad Reporting about Archaeopteryx”

  1. Nikola says:

    Can’t trust them aussies, eh?

    Thanks for the write-up.

  2. These sensation-driven journalists seem to swoop on anything about evolution that introduces new theories and evidence and start with the usual dumb claims “Did Darwin Get It Wrong” or “Our Ideas of Evolution are Turned Upside-Down” when all that has happened is a fossil was re-classified or we changed a branch in a clade or something. Just because some details have changed doesn’t mean the entire theory is suddenly “wrong”. This is a huge misconception about evolution and indeed about science in general.

  3. Jim Shaver says:

    So, Steve, I want to make sure I understand what you are saying about where Archaeopteryx fits on the evolutionary tree. Although you suggested that it is possible, I think you are saying that it is unlikely that Archaeopteryx belongs to a branch that developed flight capability independently of the branch that lead to extant birds. I think you are saying that, while no modern descendants of Arhaeopteryx exist, Archaeopteryx and extant birds most likely share a common ancestor that developed flight capability. I.e., from the theropod dinosaurs, first came a branch with flight-capable wings, followed by two (of many) separate branches, one that included Archaeopteryx (a branch that eventually died out) and one that lead to birds (including all modern birds).

    Do I have that right, in your opinion?

  4. ccbowers says:

    “The problem with this reasoning is that we almost never find specimens that are literal direct ancestors to extant species”

    This seems to me to be a result of a bias towards extant species, as if extinct species don’t count. This may be related to the incorrect perception that evolution is directional and progressive, and that this resulted in the animals we have today (and humans being the ultimate endpoint). It is not surprising that the people critical of evolution have this perspective and lack of understanding

  5. cc – you are exactly correct.

    Jim – That’s basically what I am saying, but it is more complex than that, and I deliberately hedged because right now we just don’t know. This is what I think we can say based upon current evidence (but would love to chat with an actual expert about it).

    Feathers developed very early in the theropod line. There are now many genera of feathered theropods.

    These feathers developed to various degrees. In some lines feathers developed the typically anatomy of flight feathers – similar to modern birds.

    In some of those lines actual flight evolved. It may have developed once, or more than once. If more than once, then it probably developed from theropod genera that already had feathers compatible with flight.

    To make things more complicated, some species may have secondarily lost the ability to fly.

    Microraptor is one candidate for an independent evolution of flight. It has four wings. From my reading it seems like this is still an open question.

    So – I don’t think we know if Archaeopterxy branched off from the line that lead to birds before or after the common flying ancestor. But even if it was before and it evolved flight independently, it was probably close to the split because it shares “modern” flight feathers with all flying species.

    Also – “flight” is not a black and white thing either. It’s a pretty broad continuum. Archaopteryx was a very bad flyer, by modern bird standards, and was definitely not far along the path to flight. I have read some dispute about whether it could sustain flight or not. But I think the consensus is it could fly to some degree.

    The picture is still incomplete enough that there are likely more surprises in store.

  6. rezistnzisfutl says:

    Yea all you have to do to see what’s happening with this is go to one of the Yahoo or LiveScience articles’ comments sections. As predicted, the creationists are running away with it as if this singlehandedly debunkes Theory of Evolution and evolutionary biologist finally agree that their god actually did it, validating what they knew all along.

    Shining examples as products of a combination of the US education system and fundamentalist religion. Creationists are a neverending source of amusement and awesome displays of sheer and utter jaw-dropping ignorance and scientific illiteracy.

  7. locutusbrg says:

    It is the uncertainties of evolution that make it good science, not the reverse. Otherwise it would be like the special pleadings the creationists use to discount evolution. “Transitional fossils were placed by the Devil to confuse us about the truth in the bible.”

    If there is no room for refinement of knowledge, it is dogma not science. Often the media tries to present the opposite, that science is dogma. In my opinion that misrepresentation is the reason why some lay persons belief that science is an arrogant modern religion like Scientology.
    It is not just news reporting that misfires, science as arrogant dogma is also a reoccurring theme in entertainment as well.

  8. Rob-bear says:

    I don’t know a lot about Archaeopteryx, except that my grandson and I read about it in books that a seven year old can understand. I do, however, understand your point that “evolution is also not a linear process but a messy branching bushy process,” even when it is portrayed to be somewhat linear, when you see the “lines” in books. We have built a lot of ideas on partial information, as in the case of Iguanodon (where his thumb and nose were initially confused). But, clearly, it is some kind of transitional creature. Even a believer like me can understand that.

  9. QuestionEverything says:

    It’s a shame that a brilliant discovery has to be subverted by idiots with ideological agendas. The media don’t do any favours in these instances either. It’s like these creationist sympathisers have their fingers on the trigger just waiting for a scientific discovery that they can twist to incorrectly validate their beliefs.

    Mind you, as Steve shows, misconceptions are often a chance to explain what is really going on, so thanks Steve.

    Archaeopteryx is still the reigning champions of fossil finds and we knew it would be the only fossil to fill the bird-dinosaur transitions.

  10. SteveA says:

    “Creationists, however, are likely to latch onto the terrible reporting about this new analysis as if it destroys one of the “icons of evolution.”

    Is the usual BS news-cycle. The media take some messy science, compresses it down to a few basic immutable ‘factual diamonds’ then starts shrieking when new evidence comes along to refine the story.

    For them it’s a win-win situation, the ‘facts’ make a good headline and so does the ‘controversy’.

    Support your friendly neighborhood science bloggers.

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