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Uploaded:2018-12-21
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Feathers might have originated tens of millions of years before we'd thought, and a 3D rendering of ankylosaur nasal passages lends new insight into how they stayed cool.

Hosted by: Hank Green

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Sources:

Feathered pterosaurs:
https://www.eurekalert.org/emb_releases/2018-12/uob-ndp121218.php
https://www.nature.com/articles/s41559-018-0728-7
https://www.nationalgeographic.com/science/phenomena/2015/03/23/sciencespeak-pycnofiber/
https://archosaurmusings.wordpress.com/2009/08/05/what-on-earth-are-pycnofibers/
https://www.scientificamerican.com/article/pterosaurs-just-keep-getting-weirder/
Ankylosaur noses:
https://www.eurekalert.org/emb_releases/2018-12/p-alr121218.php
https://plos.my.salesforce.com/sfc/p/#U0000000Ifis/a/0B000000Pxar/f0r2vCz6xFGQy8hWga6XmkCxxhOgV2E00H8uyku_8uw

Images:

https://commons.wikimedia.org/wiki/File:Rhamphorhynchus_munsteri.jpg
https://en.wikipedia.org/wiki/File:Hatzegopteryx.png
https://en.wikipedia.org/wiki/File:Pteranodon_sternbergi_pair.jpg
https://en.wikipedia.org/wiki/File:Triceratops_prorsus_old.jpg
https://en.wikipedia.org/wiki/File:Stego-marsh-1896-US_geological_survey.png
https://commons.wikimedia.org/wiki/File:Falcarius_white_background.jpg
https://www.nature.com/articles/s41559-018-0728-7
https://en.wikipedia.org/wiki/File:Ankylosaurus.jpg
https://commons.wikimedia.org/wiki/File:Ankylosaurus_armor.png
https://www.eurekalert.org/multimedia/pub/188424.php
https://en.wikipedia.org/wiki/File:Ankylosaurus_skull_AMNH.jpg
https://commons.wikimedia.org/wiki/File:Respiratory_System_(Illustration).png
https://www.eurekalert.org/multimedia/pub/188424.php
https://www.eurekalert.org/multimedia/pub/188299.php?from=415179
https://www.eurekalert.org/multimedia/pub/188298.php?from=415179
https://en.wikipedia.org/wiki/File:Arambourgiania_philadelphiae.png
[♪ INTRO].

Today, the last living lineage of dinosaurs, the birds, are masters of flight. But 200 million years ago or so, giant reptiles called pterosaurs ruled the skies.

And a new study suggests flight wasn’t the only trait they shared with modern birds. Just this week, paleontologists published evidence of what they say are feathers from pterosaur fossils, pushing back the origin of feathers some 70 million years, and suggesting that all dinosaurs may have had some kind of feathers. A slew of well-preserved fossils with simple feathers in the late 1990s cemented the idea that birds are dinosaurs, and that some dinosaurs sported plumage.

Since then, paleontologists have been trying to figure out when feathers first evolved. The most recent evidence pointed to the first feathers occuring on the common ancestor of ornithischian dinosaurs, the group that contains Triceratops and Stegosaurus, and the coelurosaurs, the group of dinosaurs which includes the ancestor of today’s birds. And that would mean those first feathers likely emerged somewhere around 150 to 180 million years ago.

But these new findings, described in the journal Nature Ecology and Evolution, suggests they evolved much earlier, like 230 to 250 million years ago, because that is about when the pterosaurs split off from the rest of their reptilian kin. Now, it’s been known for some time that pterosaurs were somewhat fuzzy. Fossils have suggested they were covered in pycnofibers, a kind of, like, single-filament fluff that looks a bit like mammalian hair.

But until this point, pycnofibers hadn’t been considered true feathers because they didn’t branch at all and didn’t look much the quills from dinosaurs. In fact, scientists weren’t really sure what they were at all, which is why they gave them a totally different name. In this latest paper, the researchers literally put two pterosaur specimens from China under the microscope; they found four different forms of pycnofibers.

These included little bundles of fibers that branch from the base, making them look a lot like down feathers, and larger, unbranched ‘bristles’ that are similar to feathers found on dinosaurs and modern birds. Paleontologists still aren’t sure of the exact function of these so-called feathers, but most likely, they were used for insulation. Pterosaurs were active fliers and had to keep their muscles warm enough to power that flight.

It’s also possible they streamlined the animal’s bodies, making them more aerodynamic, or that those bristles, which were found near the pterosaurs’ mouths, may have helped their sense of touch while flying or when handling prey, kind of like whiskers on a cat. Whatever the function, if these pycnofibers are truly feathers, then the origin of feathers happened a lot further back than paleontologists thought. The authors of this paper think they first appeared in an ancient ancestor of both pterosaurs and dinosaurs.

And that would mean even non-bird-like dinosaurs might have had quills or modified feathers, or the genes to make them, anyway. Like how pigs and whales technically have hair, even though they aren’t, like, fuzzy. But other scientists have criticized this research, saying that it’s more likely that pterosaurs independently evolved, like, a neat skin covering that helped them keep warm.

Some even doubt that the pycnofibers are for warmth. Instead of being feather or fur-like, the fibers could have strengthened their wings somehow. So this paper has started a pretty heated discussion in the paleontology community, and let me tell you, the paleontology community can have some heated discussions.

And this is one that isn’t gonna cool down until a lot more fossils are found and examined. In other dinosaur related news, scientists now believe that armored ankylosaurs used their elaborate nasal passages to regulate their body temperature. Ankylosaurs are probably better known for their club-like tails than their fancy noses, but that didn’t stop scientists from wondering what those pipes were for.

Mammals use convoluted nasal passages called turbinates as a kind of air conditioner, warming and humidifying air when it’s breathed in and cooling and drying air when it’s breathed out. Because ankylosaurs had a single long, bendy tube, rather than the many winding passages of turbinates, paleontologists thought they might use them for vocalizations instead. In this latest paper published in PLoS One, they put the heat exchange hypothesis to the test by making 3D digital reconstructions of the fossilized nasal passages from two ankylosaur species.

Then, they computer modelled how air moved through their noses and what happened to heat along the way. What they found was that all those twists and turns likely recovered a lot of heat from the air when the animals exhaled which could then be used to warm the next breath coming in. And ultimately, their noses would use 65 to 84 percent less energy, which is pretty similar to the energy mammals save with their turbinates.

When the researchers digitally straightened out the ankylosaur nasal passages, the energy savings were gone, telling them that the twists and turns were important. As well as heating air coming in to the lungs, the long, twisted passages could also shed excess body heat from the dinosaurs’ brains. Because, you know, it’s important to keep a cool head when you’re roaming around in the Cretaceous.

While it is difficult to be certain of all of this without, like, a live ankylosaur in the lab, these simulations get scientists pretty close to understanding the ecology of these armoured creatures. Similar, twisted nasal passages have also been seen in other big dinosaurs like sauropods, making scientists question which came first, big bodies or elaborate nose holes. And regardless of whether its feathery fluff or elaborate noses, our picture of evolution is constantly changing as new fossil evidence is dug up or scientists find new ways to peer closer at the fossils they already have.

Thanks for watching this episode of SciShow News! We’re all going to be taking the weekend off here at SciShow, and if that leaves you really just jonesing for more SciShow content, more amazing science, we have a podcast for you, it’s called SciShow Tangents, it’s a weekly podcast produced in collaboration with WNYC studios. Every Tuesday, four of the people who work on SciShow YouTube channels, including me, pick a theme and we all try to one-up each other with awesome science facts and research we find based on that theme.

The show has different segments, like one where someone presents a true fact alongside two that definitely are not true, and everyone has to guess which ones were made up. We usually end up going on a bunch of tangents, hence the name of the podcast, and we try to end every episode with a fact about butts. We’ve been having a ton of fun with it!

I love listening to it, which is, I feel like, a little bit weird to say, cuz I’m there while we record it. But I love it, and if you want to hear yourself, you can look for SciShow Tangents wherever you get your podcasts! [♪ OUTRO].