03/16/2018

To Flap, Perchance To Fly

4:51 minutes

fossil of a bird archaeopteryx
The Munich specimen of the transitional bird Archaeopteryx. Imprints of its wing feathers are visible radiating from below the shoulder and vague imprints of the tail plumage can be recognised extending from the tip of the tail. Credits: ESRF/Pascal Goetgheluck

Since its discovery in 1861, the winged, feathered dinosaur Archaeopteryx has been a poster child for paleontologists’ growing understanding of the evolutionary link between birds and dinosaurs.

But when did birds first fly? Could Archaeopteryx itself fly? The scientific community continues to debate how one of the earliest bird-like dinosaurs used its wings, with theories ranging from flapping, bird-like flight, to something more akin to gliding, like a flying squirrel.

[New research indicates that animals as simple as jellyfish have the need to doze.]

Now, a research team using the European Synchrotron Radiation Facility in France has unearthed clues from inside the bones of Archaeopteryx: The bones are low density, and “hollow” in the same manner as modern flying birds. At the same time, they’re shaped less like those of birds that flew long distances, like an albatross, and more like birds that flew in short bursts, like chickens.

Dennis Voeten, research author and paleontology doctoral candidate at Palacký University in Olomouc, Czech Republic, explains why these clues don’t settle the debate, but do indicate an animal capable of active bursts of flight…though perhaps in a different way from the birds of today.

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Segment Guests

Dennis Voeten

Dennis Voeten is a paleontologist at the European Synchrotron Radiation Facility in Grenoble, France.

Segment Transcript

FLORA LICHTMAN: This is Science Friday. I’m Flora Lichtman sitting in for Ira Flatow. The birdlike dinosaur Archaeopteryx was first discovered in the 1860s. And this raven-sized dino, cloaked in feathers, helped kick off the debate about the evolutionary links between reptiles and birds. And then these days, you often hear birds referred to as living dinosaurs. Like, you’ve probably seen that baby blue heron picture– we will tweet it. But Archeopteryx itself, the dinosaur that started it all, remains a bit of a mystery. Did it actually fly? Could it get off the ground? Did it glide down from trees like a flying squirrel?

In new research published this week, a team of scientists turned to the fossilized wing bones for clues. They used a synchrotron, a particle accelerator, to peer inside of those bones and look for structures that might hold clues. Here to tell us what he found is Dennis Voeten, a paleontologist and research fellow at the European Synchrotron Radiation Facility. He joins us via Skype. Welcome, Dennis.

DENNIS VOETEN: Hi, thank you very much for the invitation to join.

FLORA LICHTMAN: Thank you for coming on. So, what did you see when you looked at these bones with a particle accelerator?

DENNIS VOETEN: We visualize the mid part of the bones, specifically the humerus, which is the upper arm bone, and a bone in the lower arm. And the first moment we saw it, we immediately noticed that the bones were extremely thin walled. They look a lot like modern bird bones. And secondly, we immediately also saw that the bones were quite richly vascularized, which is consistent with a more active metabolism than was supposed by some avascular bone that was described 10 years ago from Archaeopteryx.

FLORA LICHTMAN: So does that mean they can fly?

DENNIS VOETEN: I would feel comfortable saying that we found these adaptations to be very consistent with flight.

FLORA LICHTMAN: Like a true scientist.

DENNIS VOETEN: Yes, we tested it against a lot of other archosaurs, which is a group that includes dinosaurs, pterosaurs, and crocodiles. And within that group, Archaeopteryx exclusively allies with those animals that fly. So in that regard, yes, we feel comfortable saying that it flew.

FLORA LICHTMAN: OK, so what kind of flying? Are we talking, like, albatross or chicken?

DENNIS VOETEN: Again, we looked at specific mid parts of the bone. So, for flight, you obviously require a little bit more. But because we found an indication for flight, we actually think we found an indication for active flight. We tried to reconcile it with the skeleton of Archaeopteryx. And it’s notoriously incompatible with the flight of modern birds, so we tried to sort of delimit the range of motion that was possible with what we now know about the shoulders of Archaeopteryx. And based on that, we propose for consideration a flight style that would superficially resemble a butterfly stroke.

FLORA LICHTMAN: Oh. So, not actually like a chicken. More graceful.

DENNIS VOETEN: I wouldn’t call it graceful. We literally have no idea what it would exactly look like, except that it probably did not look like that of a bird flying, including the flight of a chicken.

FLORA LICHTMAN: So how long would they stay up in the air? You know, how long would your measurement suggest they could stay in the air?

DENNIS VOETEN: That’s a very difficult question to answer, because it obviously involves a lot of other parameters that are not so well understood, like metabolism, and muscle size, and things like that. But because it allies with short flying birds, and they fly between 100 meters– maybe a kilometer for European listeners. I would say it’s probably not a lot more than that. And probably even quite a bit less.

FLORA LICHTMAN: How does this dinosaur stack up with other flying dinosaurs? Would it be the first? Where does it fall on the timeline?

DENNIS VOETEN: Yeah, that’s a very good question, because Archaeopteryx is one of the earliest known sort of early dino birds. And we’ve been focusing on Archaeopteryx for over 150 years now. However, originally through this, Archaeopteryx was considered the first bird. But recent discoveries from China have greatly enriched our understanding of this phase and has shown that there’s actually quite a broad variety of flying and potentially flying dinosaurs.

So although Archaeopteryx is among the oldest, and the oldest that we feel could have had active flight, there’s probably a lot of other very exotic material waiting in the wings somewhere. So we’re waiting for that to come out, and then we can answer your question even more accurately.

FLORA LICHTMAN: Well, I look forward to that too. Thank you again. This is Dennis Voeten, a paleontologist and research fellow at the European Synchrotron Radiation Facility, and he joined us by Skype. And if you have any follow up questions for Dennis, he’s doing an Ask Me Anything on Reddit tomorrow. Check it out.

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