September 17, 2025 • 34 mins
When exactly did feathers evolve? And for what purpose? Jorge digs in with two dinosaur paleontologists to find out.
See omnystudio.com/listener for privacy information.
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:01):
Hey, welcome to Sign Stuff, a production of iHeartRadio. I'm
hoor hitchhim, and today we're answering the question did dinosaurs
have feathers? You might think you know the answer to
this question, but as we'll learn today, the real answer
has changed significantly in the last few years. To get
the full story, we're going to talk to a couple
of paleontologies. We're going to tell us what we know
(00:25):
about the origin of feathers, which dinosaurs had them, and
why feathers evolved in the first place. I promise by
the end you want to look at dinosaurs or feathers
the same way again. Enjoy. Hey everyone, So I picked
today's topic to celebrate the release of my news book,
(00:48):
Oliver's Great Big Universe Evolution Changes Everything. It's all about
the history of life on Earth, is told by a
kid named Oliver. It's a great book for those smart
kids in your life, your nieces or nephews, your friend's kids.
I promise, if they like funny stories and you think
they might like science, I think this might be their
favorite new book series. So please check it out at
(01:11):
Great Big Universe dot net or your favorite bookseller. All right,
let's talk about dinosaurs and feathers. Now, I'm excited for
today's episode because we're gonna hear from two paletologists, one
of whom was involved in the landmark discovery that put
the origin of feathers way further back in time than
anyone expected. But before we get there, I thought it
(01:33):
was important that we covered the basics first because that's
going to help us later in the episode. And the
first question we're going to ask is what exactly is
a dinosaur? You probably think you know, but according to
our first expert, the answer is not that simple. Well,
thank you, doctor O'Connor for joining us today.
Speaker 2 (01:54):
It's absolutely my pleasure. I'm a big fan, so I'm
happy to be here.
Speaker 1 (01:57):
Awesome. Can you please tell us who you are and
what you do.
Speaker 2 (02:00):
My name is Jingme O'Connor, and I'm the associate curator
of Fossil Reptiles at the Field Museum of National Street
in Chicago. It's just a fancy complicated way of saying
that I'm a nerdy dinosaur paleontologist.
Speaker 1 (02:14):
I guess maybe for people who are not super familiar.
He tell us what exactly is a dinosaur? Like what
makes a dinosaur a dinosaur.
Speaker 2 (02:21):
Well, okay, that's not an easy question to answer. So
dinosaurs are basically a group of animals that have a
common ancestor. So, for example, all living mammals have one
common ancestor, that's why they form a true group. And
mammals are characterized by a specific set of traits that
you can then use to identify that they're mammals, like
(02:42):
milk and fur. But if only it was so easy
with dinosaurs. Unfortunately, dinosaurs are really weird and different, and
until recently we would have said things like dinosaurs have
a completely open hip socket and a bunch of traits
that for a long time really did define dinosaurs. But
then the more we find close relatives of dinosaurs, all
(03:05):
those traits we used to use suddenly got blurred. We
found that they were present in close non dinosaur animals,
or they were absent in the oldest known dinosaurs that
we started to find.
Speaker 1 (03:17):
All Right, what doctor O'Connor is saying is that the
definition of a dinosaur is not an animal that looks
a certain way or as a certain characteristic. It just
means all the animals that came from one specific common ancestor. Because,
as it turns, out, dinosaurs have cousins. Not every big,
(03:38):
cool giant reptile is a dinosaur. For example, there are
the big reptiles that eventually became crocodiles. Crogs did not
come from dinosaurs. Or those giant swimming reptiles like Ichiosaurus
or plesiosaurs that you see swimming around in the Jurassic
Part movies. Those are not dinosaurs. There's a big one Terosaurus.
(04:02):
These are the giant flying reptiles that you also see
in movies, like pterodactyls or Terranodon. But the giant wings
and the long deaks dose are not dinosaurs either. They're
more like cousins of dinosaurs. So when you're talking about dinosaurs,
you're really talking about a specific family of animals that
(04:23):
came from one specific ancestor.
Speaker 2 (04:27):
Let's just say that the ancestral dinosaur was probably a small,
warm blooded bipedal, probably carnivorous or omnivorous animal.
Speaker 1 (04:37):
So scientists think the first dinosaur, the ancestor of the
animals we call dinosaurs, probably walked on two legs, kind
of like Terrannosaurus REGs or the veloscy raptors that again
you see in the Jurassic part movies. But here's a
confusing part. Some dinosaurs branched out and went back to
walking on four legs, and that's where you get some
(04:59):
of the they're famous dinosaurs like Triceratops or the one
with the really long neck, Brachiosaurus. All Right, I promise
this will all be useful later. Now let's get to
the other basic which is what exactly is a feather.
Speaker 3 (05:15):
So my name is Maria McNamara and I am professor
of paleontology at University College Cork in Ireland.
Speaker 1 (05:23):
Can you tell us what a feather is?
Speaker 3 (05:25):
Ah, that's an interesting one. So a feather is basically
an integumentary appendage, to give it its scientific term. It's
basically made of protein, a protein called keratin. It's the
same protein that makes up our hair and nails, and
it is actually the most complex sort of tissue structure
(05:46):
that is known in vertebrate animals. Each feather has a
central sheaft with lateral side branches, and those branches have branches,
and actually the branches are organized in a spiral around
the shaft. So a feather is really the most complex
tissue structure that is known.
Speaker 1 (06:06):
From the skin all right, you probably already knew what
a feather was. But here's the thing. That description of
feathers only applies to modern feathers. Early feathers, scientists think
we're a lot simpler. They look more like hairs, except
they're not hairs. How are they related to hairs?
Speaker 3 (06:28):
What feathers and hair have in common is that they're
both outgroots from the skin, and they're both made of
keroten protein. But that's where the similarity ends because hairs,
unlike feathers, they don't branch, and hairs are solid. If
you slice through a hair and look at us onto
the microscope, you'll see a solid cylinder of keroten protein,
(06:52):
whereas if you slice through a feather, it's hollow in
the middle. So that's one major difference. And also in hairs,
we have a form of keratin called alpha keratin. Alpha
kerosin forms a helix, but the kerosion that's in feathers
has traditionally been called beta keratin, and that looks like
a corrugated tin roof, so it has an up and
(07:14):
down zigzag corrugated pattern. So the structure of the proteins
is very different.
Speaker 1 (07:20):
It makes hair sound a lot more boring.
Speaker 3 (07:23):
Hair is still a very interesting structure, but structurally it
is simpler than feathers.
Speaker 1 (07:29):
So when we talk about dinosaurs, now you know what
we mean. And when we talk about feathers, you also
know what we mean. And now we get to the
question did dinosaurs have feathers? And I'll just tell you
the answer to this question is kind of shocking. At least,
it really took me by surprise. Where did feathers come from?
Speaker 3 (07:51):
Ha? If I could answer that question, I would get
I don't know, a normal prize or something.
Speaker 1 (07:58):
Yeah, that's good, let's get you noble price.
Speaker 3 (08:00):
Yeah. Yeah, Well, look that question, where haven't you feathers
come from? That's the question that's been driving our research
over the last fifteen years.
Speaker 1 (08:10):
All right. According to doctor McNamara, the answer to the
question did dinosaurs have feathers? Or where did feathers come from?
Has changed several times over the last thirty years, And
it's changed because we keep finding fossils that totally rewrite
what we think we know. So I'm going to take
you back starting in the nineteen nineties.
Speaker 3 (08:31):
So you know, if we were to go back, let's
say to nineteen ninety, right, and if you would ask
me where the feathers come from, I would have told you, well,
that's easy. Birds evolved feathers. Feathers are a feature that
are unique to birds.
Speaker 1 (08:45):
Why do you think that is?
Speaker 3 (08:46):
Because before the nineties, you know, they were the only
modern animals for which we had feathers. We hadn't discovered
any fossils at that point that preserved feathers.
Speaker 1 (08:55):
And so the idea is that when birds evolved, part
of what made them birds was that they developed feathers exactly.
Speaker 3 (09:02):
We thought that feathers were one of the defining characteristics
of birds. And I mean, there's other features that define birds,
having a really enlarge, exaggerated sternum, to have big, huge
chest muscles for powering flight. Birds have special little bones
in the shoulder girdle, they have special shape of their
clavical These were all thought to be defining characteristics of birds,
(09:27):
and feathers were thought to be one of those features.
We simply hadn't found any fossils that had evidence of feathers.
Speaker 1 (09:34):
So before the nineteen nineties, we just thought feathers were
a birth thing. Modern birds were the only animals we
had ever seen with feathers, so we thought birds were
the ones that evolved them. That basically feathers started with birds,
which was a totally reasonable thing to assume. But then
something happened in the mid nineteen nineties.
Speaker 3 (09:56):
But then in the mid nineteen nineties, the world was
literally turned up side down with the dramatic discovery that
some dinosaurs also had feathers.
Speaker 1 (10:07):
Yes, the nineties didn't just give us grunch rock. The
nineties gave us one of the most significant dinosaur discoveries
in history. We're gonna talk about this discovery and how
it and other discoveries changed when we think feathers evolved.
Stay with us. We'll be right back, and we're back Okay.
(10:38):
Before the nineteen nineties, we thought feathers were just a
bird thing, and the story everyone agreed to was that
birds were the ones that evolved feathers. But then in
the mid nineteen nineties there was a discovery that rocked
everything we thought was true.
Speaker 3 (10:55):
So in the nineteen nineties there was the discovery of
dinosaurs preserved soft tissues from the early Cretaceous je Hall
biota of China, and the Jehall biota is now recognized
as one of the most important fossil localities in the world.
So these fossils are found in northeast China, and they
(11:16):
preserve lots of different types of animals, with everything from plants, insects, turtles,
some early mammals, and lots of dinosaurs. What was discovered
was a dinosaur called sinosrouptrics. So Sinus ruptrics is a
small little therapod dinosaur and it's only about thirty centimeters tall,
and it preserves dark organic matter, dark remains of its
(11:41):
soft tissues around the head, down the back of the neck,
along the body, and along the tail. And when the
Chinese research team looked at these fossils under the microscope,
they could say that that brown material it actually had structure,
and that structure was that it was posed of thousands
(12:01):
of tiny filaments, and the Chinese team surmised that these
filaments were in fact a very simple sort of feather.
Speaker 1 (12:10):
Basically, researchers in China discovered a dinosaur with feathers. It's
a tiny dinosaur, only about a foot tall, and what
the fossil showed was that it had kind of a
mohawk running down its back and a fuzzy tail with
stripes that looks sort of like the tail of a raccoon. Now,
I know what you're thinking, that doesn't quite sound like feathers,
(12:32):
and that's why this fossil was a little controversial.
Speaker 3 (12:37):
Now this proved massively controversial because you know, the feathers
that were all very familiar with, they have that clear
pattern of branching. They have the central shaft and the
lateral branches. But what not many people know is that
some birds do have feathers that have a very simple structure.
So some birds have feathers that are just simple filaments
(13:01):
that don't have any branching. So turkeys, for instance, they
have these weird, little spiky feathers that grow out of
their chin and they are bristles. They are just a
simple filament. And there's a bird called the black coucal,
and the black coucal the juveniles they have feathers that
don't branch. So there are modern examples of these sorts
(13:25):
of feathers, and so the Chinese team said, these are
so simple in structure, it's possible that these dinosaurs are
showing us some of the very earliest types of feathers.
Speaker 1 (13:38):
Okay, so this wasn't a clear slam dug that dinosaurs
said feathers. People thought, well, they could be hairs. Well,
how do we know this are not just hairs.
Speaker 3 (13:50):
Yeah, so that's a very good question, and to be honest,
that question wasn't answered for quite some time because really,
if you want to prove that they're not hairs, you
need to prove that they're hollow and not solid. So
for a long time those structures were really controversial because
the Chinese teams they weren't doing the sort of microscopic
(14:10):
analyzes that were necessary to prove that they were feathers.
And what was really exciting was when the dinosaur Microraptor
was discovered. So this is a feathered dinosaur that preserves
structures that are onlyquivocally feathers. You can't argue with them
because they have the shaft, they have the lateral branches,
and they even have the branches on the branches. They
(14:33):
have the barbs and the barbules, and so those are
effectively modern type feathers. They're identical to the feathers that
we see in modern birds. So once Microraptor was discovered,
when then there was no disputing the fact that at
least some dinosaurs had true modern type feathers.
Speaker 1 (14:54):
All right, here's a little bit of context. We've known
for a while that birds evolved from dinosaurs. If you've
heard of archaep terics, if also the kind of looks
halfway between a dinosaur and a bird that was discovered
in eighteen sixty one. What the discoveries in China did
was pushed the origin of feathers back to before archaep
(15:15):
terics and into the kind of dinosaurs that directly evolved
into birds. These dinosaurs are called therapods. So after these discoveries,
people thought, wow, feathers didn't start with birds. They started
right before birds, in the dinosaurs that evolved into birds.
Speaker 3 (15:34):
So then you know our concept of rock feathers were
and where they came from. We felt, well, maybe feathers
are something that evolved in birds and they're very close
dinosaur relatives, that they were something that evolved just in
the bird like dinosaurs the therapods, and that's what we
thought for pretty much twenty years.
Speaker 1 (15:57):
So for twenty years that was the story. Did dinosaurs
of feathers? The answer was yes, a few dinosaurs, the
ones that directly evolved into birds, had them, and that's
when feathers started, but then that all changed in twenty thirteen.
Speaker 3 (16:15):
But then in twenty thirteen, we discovered a completely different
type of dinosaur that's not related to the birds like
dinosaurs at all, and each had feathers.
Speaker 1 (16:25):
Okay, let's get to the big twenty thirteen discovery. What
doctor McNamara and her colleagues found was another dinosaur with feathers,
but this one was different.
Speaker 3 (16:38):
It's an Ornithiskian dinosaur, so in the same family as
viserah Thops and ankylosaurs, you know, these big, lumbering kind
of beasts. So we found a quart repeated dinosaur, a herbivore.
Each had feathers, and it didn't just have one type
of feathers, it had three types of feathers, So that
(16:59):
really rocked the world.
Speaker 1 (17:01):
What they found was a dinosaur they called Colinda dromuse,
and it had hair like feathers on its head, chests,
and legs. And what's significant about this dinosaur is that
it's on a totally different branch of dinosaurs than the
dinosaurs that evolved into birds. This one is more related
to Triceratops, which is the big four legged dinosaur with
(17:23):
the three horns, and this means feathers were even older
than people.
Speaker 3 (17:27):
Thought by finding feathers in a more primitive dinosaur. If
these two groups of dinosaurs had them, well, that kind
of implies that the genetic machinery for making feathers may
have actually evolved very early during dinosaur evolution, so that
these distantly related types of dinosaurs had the ability to
(17:51):
produce feathers.
Speaker 1 (17:53):
What doctor McNamara is saying is that the fact two
distant dinosaur cousins had feathers implies that their ancestor also
had feathers. It's sort of like if you and your
cousin have the same gene, the gene probably didn't start
with you. You both probably got it from your common
grandmother or grandfather. This meant that feathers didn't start with
(18:14):
the dinosaurs that became birds. They go back even further.
Speaker 3 (18:19):
There is also the option that maybe two groups of
dinosaurs evolved feathers independently, but we actually considered it much
more likely that this shared possession of feathers reflects common ancestry,
that they were present in the common ancestor. So that
was the stage of play for about six or seven years.
Speaker 1 (18:41):
That's right. That story only lasted about six years. And
that's because in twenty nineteen, doctor McNamara and her colleagues
found another fossil that totally threw that story out the window.
When we come back, we'll talk about that discovery and
we'll hear from our experts why scientists thinks evolved. Stay
(19:01):
with us, you're listening to science stuff. Welcome back, all right.
We're telling the story of what we know about dinosaurs
and feathers. In twenty thirteen, palontologist doctor Maria McNamara was
(19:24):
part of a team that made a remarkable discovery. The
fund feathers is a distant cousin of the dinosaurs that
eventually evolved into birds. And this meant that feathers didn't
evolve with birds, nor did they evolve with the dinosaurs
that became birds. Other dinosaurs had them, which meant the
origin of feathers went back even further. But how far back,
(19:47):
which dinosaur ancestor was it that first evolved feathers. The answer,
it turned out, was even more surprising than anyone expected.
Speaker 3 (19:57):
That was the stage of play for about six seven years,
and then in twenty nineteen we discovered feathers in a
completely different group of animal. We discovered feathers in pterosaurs.
Speaker 1 (20:12):
That's right, Doctor McNamara and her colleagues found feathers in
animals that aren't even dinosaurs. They found feathers in pterosaurs. Now,
what are pterosaurs.
Speaker 3 (20:25):
These are the giant flying reptiles, the cousins of dinosaurs
that roamed the skies during much of the Mesozoic. So
we found these little baby pterosaurs, these two juveniles from
China that literally had feathers covering their entire bodies, and
they had four different types of feathers. They had some
(20:48):
simple hair like feathers that we have found on lots
of dinosaurs and that are also present in modern birds,
and three types of branched feather feathers that branch at
the base, feathers that branch and shaffway along the shaft,
and even some feathers that branch at the tip. So
we find these in these juvenile terosaurs.
Speaker 1 (21:08):
So they found feathers, real feathers in animals that are
not dinosaurs. They're more like the cousins the whole group
of dinosaurs. Now what does this mean, Well, there are
two possibilities. Either pterosaurs, the flying cousins of dinosaurs, also
evolved feathers, and the feathers look the same by sheer coincidents,
(21:28):
or feathers evolved way in the past before these two
groups of animals branched off. Now, the first possibility that
both groups of animals involved feathers and they look the
same by sheer coincidents does sometimes happen in nature. It's
called convergent evolution. For example, birds evolved wings, but so
(21:49):
that bats and sharks evolved fins and a streamlined body,
but so that whales. But in the case of feathers,
paleontologists argue this is very unlike likely. Here's how doctor
Jingme O'Connor explains it.
Speaker 2 (22:04):
The one of the ways that paleontology makes hypotheses is
based on the principle of parsimony.
Speaker 1 (22:11):
Okay, parsimony in general means being economical or cheap, but
in the context of science, it means that if you
have two possibilities, usually the one that's right is the
simpler one. If you've heard of Alkham's razor, it's pretty
much the same thing.
Speaker 2 (22:29):
It's basically assuming that instead of evolution evolving these feathers
in pterosaurs and then also evolving them a different time
in dinosaurs. Since these groups are so closely related, it
would be most parsimonious that the common ancestor of these
two groups already had these features. And the reason it's
(22:49):
present in pterosaurs and dinosaurs is because they both inherited it.
Speaker 1 (22:54):
What doctor O'Connor is saying is that it would be
a stretch for both dinosaurs and pterosaurs to evolve feathers
independently out of the blue, especially because a the two
groups of animals are closely related, so it's not a
stretch to imagine their common ancestor had feathers, and b
Feathers are complex, They're not easy to just suddenly evolve.
Speaker 2 (23:18):
Feathers are complex structures, complex poratinous outgrowths. So the more
complex the structure is, like, the more unlikely it is
to evolve, you know, rather than having these complex like
caoratinous external structures evolving a bunch of different times and
all these dinosaurs and also in pterosaurs, it makes more sense,
(23:39):
or it's more parsimonious for it to evolve once in
the common ancestor.
Speaker 1 (23:45):
And if you assume feathers evolved in a distant ancestor
of dinosaurs and pterosaurs, it means that feathers evolved before
dinosaurs existed.
Speaker 3 (23:57):
We favor the idea that the presence of feather is
in terosaurs and dinosaurs. We feel that this implies that
the genetic networks required to grow feathers must have evolved
in the common ancestor of pterosaurs and dinosaurs, and that
common ancestor we predicted would have lived seventeen million years
(24:18):
earlier than both.
Speaker 1 (24:21):
And this leads to the shocking answer I promised. If
feathers evolved before dinosaurs became their own branch of animals,
it means the ancestor of all dinosaurs had feathers, which
means all dinosaurs had feathers. It's not that a few
dinosaurs and feathers, or that some dinosaurs had them. They
all had feathers, or at least they all had the
(24:44):
genes the ability to grow feathers. We'll get to what
that means in a minute, but first it turns out
that's not the end of the story.
Speaker 3 (24:54):
And that was the accepted state of play for the
last few years and most of the community. You know,
we're happy with the evidence that we put forward that
these structures were feathers, because we had evidence from microscopic analyzes.
We had evidence from chemical analyzes that they basically contained
the same sorts of pigment granules as feathers, and they
(25:15):
contained you know that we had chemical evidence for the
kerot and protein. But this year we produced really a
quite shocking discovery.
Speaker 1 (25:23):
What another shocking discovery.
Speaker 3 (25:26):
We were looking in some early Triassic rocks. We were
looking at animals that really they are very distant relatives
of dinosaurs and pterosaurs, and we found that some of
these very early Triassic reptiles, they preserve this remarkable structure
(25:47):
on their back that's made of these materials which look
so similar to feathers. They contained the same pigment granules
as feathers, but they lacked branching, so they don't fit
our kind of conventional idea of what a feather is,
So to be very conservative, we probably shouldn't call them feathers.
(26:08):
They do tell us that there were animals living in
the early Triassic that had structures that might have had
many of the same functions as feathers.
Speaker 1 (26:20):
So just this year, in twenty twenty five, doctor McNamara
and her colleagues discovered proto feathers or prefeathers in an
animal that lived way before dinosaurs, which means it wasn't
just the ancestor of dinosaurs that had feathers, go even
further back. How far back scientists don't know. So here's
(26:40):
the working hypothesis. Feathers, or the genetic mutation that allows
an animal to grow these complex proteins into a structure
on their skin, evolved long before dinosaurs, and we see
feathers today in birds which descended from dinosaurs, which means
all dinosaurs probably had those genes. But does that mean
(27:00):
that t Rex or every dinosaur basically looked like a
giant chicken. Not really. Palatologists think all dinosaurs had the
capacity to grow feathers, but some didn't use it red
least once they got big, they didn't need it, which
brings us to the reason feathers might have evolved in
the first place, staying worn.
Speaker 2 (27:25):
So it's very likely that large dinosaurs, if not completely
lost their feathering, like highly reduced it. And so that's
why I brought up the analogy with the elephant. I mean,
elephant is like a big mammal, so it has to
get rid of body heat. It also lives in a
really hot place, but it hasn't completely lost its fur.
Speaker 1 (27:46):
It still has it.
Speaker 2 (27:47):
It's just very sparse. So that's why I'm just making
the argument that maybe big dinosaurs would have highly reduced
their feathering, but would they completely lose it?
Speaker 1 (27:58):
I don't know.
Speaker 2 (27:58):
Like, I can't think of any mammal that has completely
lost its hair except for aquatic ones. I don't know
if like we have had some hair somewhere, whales or hair,
that'd be so funny.
Speaker 1 (28:09):
I guess maybe a question is, what's the evolution of
those from proto feathers to the feathers we see, like
the beautiful feathers we see birds today. What was that progression?
Speaker 2 (28:18):
So I just want to give a disclaimer that the
progression from proto feather to complex fractal feather, which we
call prenaceous feathers, it's highly hypothetical.
Speaker 1 (28:30):
Gosh, we could spend a whole other episode just in this,
but here is the working hypothesis. Feathers likely evolved to
keep small animals warm, sort of like fur. You can
find this in animals dating bag to be four dinosaurs.
But then two things happened. Some dinosaurs started getting big,
and so they stopped needing this coat to stay warm,
(28:51):
which is why you only see baby pterosaurs covered in
feathers and why paleontologists think maybe baby t rexes had feathers,
but big adult ones didn't. They probably shed a lot
of it off, so no giant t rex chickens probably
And also evolution figured out feathers were also good for
other things.
Speaker 2 (29:13):
So exactation is the fancy evolutionary biology word for evolution
taking a feature that has evolved for some other reason
and then hijacking it for another function. So sinoserapter its
fuzzy little dinosaur covered in proto feathers, but tail is striped.
These feathers are not just being used for thermal regulation.
(29:35):
They're also being co opted for communication, either within a
species like hey you know wag my tail. Hey you're
also sinoserapteris what's up? Or Hey, this is my territory,
go away, you know, like just some kind of display,
some kind of communication. We really can't say.
Speaker 1 (29:50):
So that's why you see some dinosaurs with the fancy
complex feathers. They used it for mating or to intimidate
other dinosaurs, and then eventually the di dinosaurs that would
evolve in the words figured out, hey, these feathers are
also pretty good for flying.
Speaker 2 (30:08):
So for example, feathers like the fancy, panacious feathers, they
evolve for some other purpose and we're exacted for flight.
Speaker 1 (30:14):
Like I said, we could go on a whole tangent
about feathers. But to recap the main question of the episode,
did dinosaurs have feathers? The answer is yes, they all did,
and this is something we just recently found out. Does
that mean all dinosaurs looked like giant chickens? Not necessarily,
but it definitely means they're a lot fuzzier than we
(30:36):
thought before. All Right, close the episode, here's doctor McNamara.
Speaker 3 (30:42):
So that's where we are. It opens up all sorts
of ideas about where did feathers evolve? You know, are
we going to find true feathers in the early Triassic?
If that's the question we're asking, Well, these new fossils
from the Triassic tell us that in order to find
the answers for feather origins, we need to look back
(31:04):
in even all the rocks before the Triassic, And to
be honest, that's somewhere where we never thought we were
going to have to go.
Speaker 1 (31:13):
That is amazing. Last question I guess is what gets
you excited about finding the origin of feathers.
Speaker 3 (31:21):
Because they are just one of the most complex tissue
structures that vertebrates have, and because there's so much kind
of required to produce them. I just really want to
know why did vertebrates start producing these, Why did they
give us an advantage? Why did they give our deep
deep ancestors an advantage. I'm just really intrigued by it.
(31:43):
What really was driving evolution once we come on to land,
What do we do in this new environment? What are
the major challenges? You know, these are just really big
evolutionary questions, and we have the opportunity with feathers actually
to address some of that. So I just think it's
really fun.
Speaker 1 (32:03):
That's so wonderful. Well, I hope you do get a
Nobel Prize for the Professor McNamara, or at the very least,
I hope you get a feather in your cap.
Speaker 3 (32:12):
Thank you, Thank you very much.
Speaker 1 (32:15):
All right, Hey, be sure to check out my latest book,
Oliver's Great Big Universe Evolution Changes Everything. Look for it
in your favorite online or local bookstore, or go to
Great Big Universe dot Net to learn more. Thanks a lot,
See you next time you've been Listening to Science Stuff
production of iHeartRadio Britten and produced by me Or Hitcham,
(32:38):
edited by Rose Seguda, executive producer Jerry Rowland, and audio
engineer and mixer Kasey Peckram. You can follow me on
social media. Just search for PhD Comics and the name
of your favorite platform. Be sure to subscribe to sign
Stuff on the iHeartRadio app, Apple Podcasts, or wherever you
get your podcasts, and please tell your friends we'll be
back next Wednesday with another episode. Hey, if you're wondering
(33:02):
how feathers can survive the fossilization process, here's our first
ever appendix with doctor Magnamara's explanation. How do these feathers
get preserved as fossils? I thought only like bones got
preserved as fossils.
Speaker 3 (33:15):
So yeah, ninety nine times out of one hundred, you're right.
And usually when animals die, bones are the only things
that end up getting preserved. But sometimes the soft tissues
of animals and plants they don't rot away completely. In
the case of feathers, they're made of those proteins. They're
pretty tough, they're pretty robust, and they actually undergo transformations
(33:41):
when the rocks are buried and the molecules start to
link together. They form large polymers, and it turns out
that it's really hard for bacteria to destroy those polymers,
so once they start to polymerize, it actually enhances their
preservation potential.
Speaker 1 (33:59):
So some of these proteins actually survived the fossilization products
like you can see them in the rock.
Speaker 3 (34:03):
We can actually track the three dimensional architecture of the protein.
That's what's really distinctive about feather proteins is that three
dimensional corrugated shape rather than the helical shape. So we
know for a fact that some of the earliest birds
and feather dinosaurs their feathers were made of the same
(34:24):
proteins as the feathers of modern birds.
Hey, welcome to Sign Stuff, a production of iHeartRadio. I'm
hoor hitchhim, and today we're answering the question did dinosaurs
have feathers? You might think you know the answer to
this question, but as we'll learn today, the real answer
has changed significantly in the last few years. To get
the full story, we're going to talk to a couple
of paleontologies. We're going to tell us what we know
(00:25):
about the origin of feathers, which dinosaurs had them, and
why feathers evolved in the first place. I promise by
the end you want to look at dinosaurs or feathers
the same way again. Enjoy. Hey everyone, So I picked
today's topic to celebrate the release of my news book,
(00:48):
Oliver's Great Big Universe Evolution Changes Everything. It's all about
the history of life on Earth, is told by a
kid named Oliver. It's a great book for those smart
kids in your life, your nieces or nephews, your friend's kids.
I promise, if they like funny stories and you think
they might like science, I think this might be their
favorite new book series. So please check it out at
(01:11):
Great Big Universe dot net or your favorite bookseller. All right,
let's talk about dinosaurs and feathers. Now, I'm excited for
today's episode because we're gonna hear from two paletologists, one
of whom was involved in the landmark discovery that put
the origin of feathers way further back in time than
anyone expected. But before we get there, I thought it
(01:33):
was important that we covered the basics first because that's
going to help us later in the episode. And the
first question we're going to ask is what exactly is
a dinosaur? You probably think you know, but according to
our first expert, the answer is not that simple. Well,
thank you, doctor O'Connor for joining us today.
Speaker 2 (01:54):
It's absolutely my pleasure. I'm a big fan, so I'm
happy to be here.
Speaker 1 (01:57):
Awesome. Can you please tell us who you are and
what you do.
Speaker 2 (02:00):
My name is Jingme O'Connor, and I'm the associate curator
of Fossil Reptiles at the Field Museum of National Street
in Chicago. It's just a fancy complicated way of saying
that I'm a nerdy dinosaur paleontologist.
Speaker 1 (02:14):
I guess maybe for people who are not super familiar.
He tell us what exactly is a dinosaur? Like what
makes a dinosaur a dinosaur.
Speaker 2 (02:21):
Well, okay, that's not an easy question to answer. So
dinosaurs are basically a group of animals that have a
common ancestor. So, for example, all living mammals have one
common ancestor, that's why they form a true group. And
mammals are characterized by a specific set of traits that
you can then use to identify that they're mammals, like
(02:42):
milk and fur. But if only it was so easy
with dinosaurs. Unfortunately, dinosaurs are really weird and different, and
until recently we would have said things like dinosaurs have
a completely open hip socket and a bunch of traits
that for a long time really did define dinosaurs. But
then the more we find close relatives of dinosaurs, all
(03:05):
those traits we used to use suddenly got blurred. We
found that they were present in close non dinosaur animals,
or they were absent in the oldest known dinosaurs that
we started to find.
Speaker 1 (03:17):
All Right, what doctor O'Connor is saying is that the
definition of a dinosaur is not an animal that looks
a certain way or as a certain characteristic. It just
means all the animals that came from one specific common ancestor. Because,
as it turns, out, dinosaurs have cousins. Not every big,
(03:38):
cool giant reptile is a dinosaur. For example, there are
the big reptiles that eventually became crocodiles. Crogs did not
come from dinosaurs. Or those giant swimming reptiles like Ichiosaurus
or plesiosaurs that you see swimming around in the Jurassic
Part movies. Those are not dinosaurs. There's a big one Terosaurus.
(04:02):
These are the giant flying reptiles that you also see
in movies, like pterodactyls or Terranodon. But the giant wings
and the long deaks dose are not dinosaurs either. They're
more like cousins of dinosaurs. So when you're talking about dinosaurs,
you're really talking about a specific family of animals that
(04:23):
came from one specific ancestor.
Speaker 2 (04:27):
Let's just say that the ancestral dinosaur was probably a small,
warm blooded bipedal, probably carnivorous or omnivorous animal.
Speaker 1 (04:37):
So scientists think the first dinosaur, the ancestor of the
animals we call dinosaurs, probably walked on two legs, kind
of like Terrannosaurus REGs or the veloscy raptors that again
you see in the Jurassic part movies. But here's a
confusing part. Some dinosaurs branched out and went back to
walking on four legs, and that's where you get some
(04:59):
of the they're famous dinosaurs like Triceratops or the one
with the really long neck, Brachiosaurus. All Right, I promise
this will all be useful later. Now let's get to
the other basic which is what exactly is a feather.
Speaker 3 (05:15):
So my name is Maria McNamara and I am professor
of paleontology at University College Cork in Ireland.
Speaker 1 (05:23):
Can you tell us what a feather is?
Speaker 3 (05:25):
Ah, that's an interesting one. So a feather is basically
an integumentary appendage, to give it its scientific term. It's
basically made of protein, a protein called keratin. It's the
same protein that makes up our hair and nails, and
it is actually the most complex sort of tissue structure
(05:46):
that is known in vertebrate animals. Each feather has a
central sheaft with lateral side branches, and those branches have branches,
and actually the branches are organized in a spiral around
the shaft. So a feather is really the most complex
tissue structure that is known.
Speaker 1 (06:06):
From the skin all right, you probably already knew what
a feather was. But here's the thing. That description of
feathers only applies to modern feathers. Early feathers, scientists think
we're a lot simpler. They look more like hairs, except
they're not hairs. How are they related to hairs?
Speaker 3 (06:28):
What feathers and hair have in common is that they're
both outgroots from the skin, and they're both made of
keroten protein. But that's where the similarity ends because hairs,
unlike feathers, they don't branch, and hairs are solid. If
you slice through a hair and look at us onto
the microscope, you'll see a solid cylinder of keroten protein,
(06:52):
whereas if you slice through a feather, it's hollow in
the middle. So that's one major difference. And also in hairs,
we have a form of keratin called alpha keratin. Alpha
kerosin forms a helix, but the kerosion that's in feathers
has traditionally been called beta keratin, and that looks like
a corrugated tin roof, so it has an up and
(07:14):
down zigzag corrugated pattern. So the structure of the proteins
is very different.
Speaker 1 (07:20):
It makes hair sound a lot more boring.
Speaker 3 (07:23):
Hair is still a very interesting structure, but structurally it
is simpler than feathers.
Speaker 1 (07:29):
So when we talk about dinosaurs, now you know what
we mean. And when we talk about feathers, you also
know what we mean. And now we get to the
question did dinosaurs have feathers? And I'll just tell you
the answer to this question is kind of shocking. At least,
it really took me by surprise. Where did feathers come from?
Speaker 3 (07:51):
Ha? If I could answer that question, I would get
I don't know, a normal prize or something.
Speaker 1 (07:58):
Yeah, that's good, let's get you noble price.
Speaker 3 (08:00):
Yeah. Yeah, Well, look that question, where haven't you feathers
come from? That's the question that's been driving our research
over the last fifteen years.
Speaker 1 (08:10):
All right. According to doctor McNamara, the answer to the
question did dinosaurs have feathers? Or where did feathers come from?
Has changed several times over the last thirty years, And
it's changed because we keep finding fossils that totally rewrite
what we think we know. So I'm going to take
you back starting in the nineteen nineties.
Speaker 3 (08:31):
So you know, if we were to go back, let's
say to nineteen ninety, right, and if you would ask
me where the feathers come from, I would have told you, well,
that's easy. Birds evolved feathers. Feathers are a feature that
are unique to birds.
Speaker 1 (08:45):
Why do you think that is?
Speaker 3 (08:46):
Because before the nineties, you know, they were the only
modern animals for which we had feathers. We hadn't discovered
any fossils at that point that preserved feathers.
Speaker 1 (08:55):
And so the idea is that when birds evolved, part
of what made them birds was that they developed feathers exactly.
Speaker 3 (09:02):
We thought that feathers were one of the defining characteristics
of birds. And I mean, there's other features that define birds,
having a really enlarge, exaggerated sternum, to have big, huge
chest muscles for powering flight. Birds have special little bones
in the shoulder girdle, they have special shape of their
clavical These were all thought to be defining characteristics of birds,
(09:27):
and feathers were thought to be one of those features.
We simply hadn't found any fossils that had evidence of feathers.
Speaker 1 (09:34):
So before the nineteen nineties, we just thought feathers were
a birth thing. Modern birds were the only animals we
had ever seen with feathers, so we thought birds were
the ones that evolved them. That basically feathers started with birds,
which was a totally reasonable thing to assume. But then
something happened in the mid nineteen nineties.
Speaker 3 (09:56):
But then in the mid nineteen nineties, the world was
literally turned up side down with the dramatic discovery that
some dinosaurs also had feathers.
Speaker 1 (10:07):
Yes, the nineties didn't just give us grunch rock. The
nineties gave us one of the most significant dinosaur discoveries
in history. We're gonna talk about this discovery and how
it and other discoveries changed when we think feathers evolved.
Stay with us. We'll be right back, and we're back Okay.
(10:38):
Before the nineteen nineties, we thought feathers were just a
bird thing, and the story everyone agreed to was that
birds were the ones that evolved feathers. But then in
the mid nineteen nineties there was a discovery that rocked
everything we thought was true.
Speaker 3 (10:55):
So in the nineteen nineties there was the discovery of
dinosaurs preserved soft tissues from the early Cretaceous je Hall
biota of China, and the Jehall biota is now recognized
as one of the most important fossil localities in the world.
So these fossils are found in northeast China, and they
(11:16):
preserve lots of different types of animals, with everything from plants, insects, turtles,
some early mammals, and lots of dinosaurs. What was discovered
was a dinosaur called sinosrouptrics. So Sinus ruptrics is a
small little therapod dinosaur and it's only about thirty centimeters tall,
and it preserves dark organic matter, dark remains of its
(11:41):
soft tissues around the head, down the back of the neck,
along the body, and along the tail. And when the
Chinese research team looked at these fossils under the microscope,
they could say that that brown material it actually had structure,
and that structure was that it was posed of thousands
(12:01):
of tiny filaments, and the Chinese team surmised that these
filaments were in fact a very simple sort of feather.
Speaker 1 (12:10):
Basically, researchers in China discovered a dinosaur with feathers. It's
a tiny dinosaur, only about a foot tall, and what
the fossil showed was that it had kind of a
mohawk running down its back and a fuzzy tail with
stripes that looks sort of like the tail of a raccoon. Now,
I know what you're thinking, that doesn't quite sound like feathers,
(12:32):
and that's why this fossil was a little controversial.
Speaker 3 (12:37):
Now this proved massively controversial because you know, the feathers
that were all very familiar with, they have that clear
pattern of branching. They have the central shaft and the
lateral branches. But what not many people know is that
some birds do have feathers that have a very simple structure.
So some birds have feathers that are just simple filaments
(13:01):
that don't have any branching. So turkeys, for instance, they
have these weird, little spiky feathers that grow out of
their chin and they are bristles. They are just a
simple filament. And there's a bird called the black coucal,
and the black coucal the juveniles they have feathers that
don't branch. So there are modern examples of these sorts
(13:25):
of feathers, and so the Chinese team said, these are
so simple in structure, it's possible that these dinosaurs are
showing us some of the very earliest types of feathers.
Speaker 1 (13:38):
Okay, so this wasn't a clear slam dug that dinosaurs
said feathers. People thought, well, they could be hairs. Well,
how do we know this are not just hairs.
Speaker 3 (13:50):
Yeah, so that's a very good question, and to be honest,
that question wasn't answered for quite some time because really,
if you want to prove that they're not hairs, you
need to prove that they're hollow and not solid. So
for a long time those structures were really controversial because
the Chinese teams they weren't doing the sort of microscopic
(14:10):
analyzes that were necessary to prove that they were feathers.
And what was really exciting was when the dinosaur Microraptor
was discovered. So this is a feathered dinosaur that preserves
structures that are onlyquivocally feathers. You can't argue with them
because they have the shaft, they have the lateral branches,
and they even have the branches on the branches. They
(14:33):
have the barbs and the barbules, and so those are
effectively modern type feathers. They're identical to the feathers that
we see in modern birds. So once Microraptor was discovered,
when then there was no disputing the fact that at
least some dinosaurs had true modern type feathers.
Speaker 1 (14:54):
All right, here's a little bit of context. We've known
for a while that birds evolved from dinosaurs. If you've
heard of archaep terics, if also the kind of looks
halfway between a dinosaur and a bird that was discovered
in eighteen sixty one. What the discoveries in China did
was pushed the origin of feathers back to before archaep
(15:15):
terics and into the kind of dinosaurs that directly evolved
into birds. These dinosaurs are called therapods. So after these discoveries,
people thought, wow, feathers didn't start with birds. They started
right before birds, in the dinosaurs that evolved into birds.
Speaker 3 (15:34):
So then you know our concept of rock feathers were
and where they came from. We felt, well, maybe feathers
are something that evolved in birds and they're very close
dinosaur relatives, that they were something that evolved just in
the bird like dinosaurs the therapods, and that's what we
thought for pretty much twenty years.
Speaker 1 (15:57):
So for twenty years that was the story. Did dinosaurs
of feathers? The answer was yes, a few dinosaurs, the
ones that directly evolved into birds, had them, and that's
when feathers started, but then that all changed in twenty thirteen.
Speaker 3 (16:15):
But then in twenty thirteen, we discovered a completely different
type of dinosaur that's not related to the birds like
dinosaurs at all, and each had feathers.
Speaker 1 (16:25):
Okay, let's get to the big twenty thirteen discovery. What
doctor McNamara and her colleagues found was another dinosaur with feathers,
but this one was different.
Speaker 3 (16:38):
It's an Ornithiskian dinosaur, so in the same family as
viserah Thops and ankylosaurs, you know, these big, lumbering kind
of beasts. So we found a quart repeated dinosaur, a herbivore.
Each had feathers, and it didn't just have one type
of feathers, it had three types of feathers, So that
(16:59):
really rocked the world.
Speaker 1 (17:01):
What they found was a dinosaur they called Colinda dromuse,
and it had hair like feathers on its head, chests,
and legs. And what's significant about this dinosaur is that
it's on a totally different branch of dinosaurs than the
dinosaurs that evolved into birds. This one is more related
to Triceratops, which is the big four legged dinosaur with
(17:23):
the three horns, and this means feathers were even older
than people.
Speaker 3 (17:27):
Thought by finding feathers in a more primitive dinosaur. If
these two groups of dinosaurs had them, well, that kind
of implies that the genetic machinery for making feathers may
have actually evolved very early during dinosaur evolution, so that
these distantly related types of dinosaurs had the ability to
(17:51):
produce feathers.
Speaker 1 (17:53):
What doctor McNamara is saying is that the fact two
distant dinosaur cousins had feathers implies that their ancestor also
had feathers. It's sort of like if you and your
cousin have the same gene, the gene probably didn't start
with you. You both probably got it from your common
grandmother or grandfather. This meant that feathers didn't start with
(18:14):
the dinosaurs that became birds. They go back even further.
Speaker 3 (18:19):
There is also the option that maybe two groups of
dinosaurs evolved feathers independently, but we actually considered it much
more likely that this shared possession of feathers reflects common ancestry,
that they were present in the common ancestor. So that
was the stage of play for about six or seven years.
Speaker 1 (18:41):
That's right. That story only lasted about six years. And
that's because in twenty nineteen, doctor McNamara and her colleagues
found another fossil that totally threw that story out the window.
When we come back, we'll talk about that discovery and
we'll hear from our experts why scientists thinks evolved. Stay
(19:01):
with us, you're listening to science stuff. Welcome back, all right.
We're telling the story of what we know about dinosaurs
and feathers. In twenty thirteen, palontologist doctor Maria McNamara was
(19:24):
part of a team that made a remarkable discovery. The
fund feathers is a distant cousin of the dinosaurs that
eventually evolved into birds. And this meant that feathers didn't
evolve with birds, nor did they evolve with the dinosaurs
that became birds. Other dinosaurs had them, which meant the
origin of feathers went back even further. But how far back,
(19:47):
which dinosaur ancestor was it that first evolved feathers. The answer,
it turned out, was even more surprising than anyone expected.
Speaker 3 (19:57):
That was the stage of play for about six seven years,
and then in twenty nineteen we discovered feathers in a
completely different group of animal. We discovered feathers in pterosaurs.
Speaker 1 (20:12):
That's right, Doctor McNamara and her colleagues found feathers in
animals that aren't even dinosaurs. They found feathers in pterosaurs. Now,
what are pterosaurs.
Speaker 3 (20:25):
These are the giant flying reptiles, the cousins of dinosaurs
that roamed the skies during much of the Mesozoic. So
we found these little baby pterosaurs, these two juveniles from
China that literally had feathers covering their entire bodies, and
they had four different types of feathers. They had some
(20:48):
simple hair like feathers that we have found on lots
of dinosaurs and that are also present in modern birds,
and three types of branched feather feathers that branch at
the base, feathers that branch and shaffway along the shaft,
and even some feathers that branch at the tip. So
we find these in these juvenile terosaurs.
Speaker 1 (21:08):
So they found feathers, real feathers in animals that are
not dinosaurs. They're more like the cousins the whole group
of dinosaurs. Now what does this mean, Well, there are
two possibilities. Either pterosaurs, the flying cousins of dinosaurs, also
evolved feathers, and the feathers look the same by sheer coincidents,
(21:28):
or feathers evolved way in the past before these two
groups of animals branched off. Now, the first possibility that
both groups of animals involved feathers and they look the
same by sheer coincidents does sometimes happen in nature. It's
called convergent evolution. For example, birds evolved wings, but so
(21:49):
that bats and sharks evolved fins and a streamlined body,
but so that whales. But in the case of feathers,
paleontologists argue this is very unlike likely. Here's how doctor
Jingme O'Connor explains it.
Speaker 2 (22:04):
The one of the ways that paleontology makes hypotheses is
based on the principle of parsimony.
Speaker 1 (22:11):
Okay, parsimony in general means being economical or cheap, but
in the context of science, it means that if you
have two possibilities, usually the one that's right is the
simpler one. If you've heard of Alkham's razor, it's pretty
much the same thing.
Speaker 2 (22:29):
It's basically assuming that instead of evolution evolving these feathers
in pterosaurs and then also evolving them a different time
in dinosaurs. Since these groups are so closely related, it
would be most parsimonious that the common ancestor of these
two groups already had these features. And the reason it's
(22:49):
present in pterosaurs and dinosaurs is because they both inherited it.
Speaker 1 (22:54):
What doctor O'Connor is saying is that it would be
a stretch for both dinosaurs and pterosaurs to evolve feathers
independently out of the blue, especially because a the two
groups of animals are closely related, so it's not a
stretch to imagine their common ancestor had feathers, and b
Feathers are complex, They're not easy to just suddenly evolve.
Speaker 2 (23:18):
Feathers are complex structures, complex poratinous outgrowths. So the more
complex the structure is, like, the more unlikely it is
to evolve, you know, rather than having these complex like
caoratinous external structures evolving a bunch of different times and
all these dinosaurs and also in pterosaurs, it makes more sense,
(23:39):
or it's more parsimonious for it to evolve once in
the common ancestor.
Speaker 1 (23:45):
And if you assume feathers evolved in a distant ancestor
of dinosaurs and pterosaurs, it means that feathers evolved before
dinosaurs existed.
Speaker 3 (23:57):
We favor the idea that the presence of feather is
in terosaurs and dinosaurs. We feel that this implies that
the genetic networks required to grow feathers must have evolved
in the common ancestor of pterosaurs and dinosaurs, and that
common ancestor we predicted would have lived seventeen million years
(24:18):
earlier than both.
Speaker 1 (24:21):
And this leads to the shocking answer I promised. If
feathers evolved before dinosaurs became their own branch of animals,
it means the ancestor of all dinosaurs had feathers, which
means all dinosaurs had feathers. It's not that a few
dinosaurs and feathers, or that some dinosaurs had them. They
all had feathers, or at least they all had the
(24:44):
genes the ability to grow feathers. We'll get to what
that means in a minute, but first it turns out
that's not the end of the story.
Speaker 3 (24:54):
And that was the accepted state of play for the
last few years and most of the community. You know,
we're happy with the evidence that we put forward that
these structures were feathers, because we had evidence from microscopic analyzes.
We had evidence from chemical analyzes that they basically contained
the same sorts of pigment granules as feathers, and they
(25:15):
contained you know that we had chemical evidence for the
kerot and protein. But this year we produced really a
quite shocking discovery.
Speaker 1 (25:23):
What another shocking discovery.
Speaker 3 (25:26):
We were looking in some early Triassic rocks. We were
looking at animals that really they are very distant relatives
of dinosaurs and pterosaurs, and we found that some of
these very early Triassic reptiles, they preserve this remarkable structure
(25:47):
on their back that's made of these materials which look
so similar to feathers. They contained the same pigment granules
as feathers, but they lacked branching, so they don't fit
our kind of conventional idea of what a feather is,
So to be very conservative, we probably shouldn't call them feathers.
(26:08):
They do tell us that there were animals living in
the early Triassic that had structures that might have had
many of the same functions as feathers.
Speaker 1 (26:20):
So just this year, in twenty twenty five, doctor McNamara
and her colleagues discovered proto feathers or prefeathers in an
animal that lived way before dinosaurs, which means it wasn't
just the ancestor of dinosaurs that had feathers, go even
further back. How far back scientists don't know. So here's
(26:40):
the working hypothesis. Feathers, or the genetic mutation that allows
an animal to grow these complex proteins into a structure
on their skin, evolved long before dinosaurs, and we see
feathers today in birds which descended from dinosaurs, which means
all dinosaurs probably had those genes. But does that mean
(27:00):
that t Rex or every dinosaur basically looked like a
giant chicken. Not really. Palatologists think all dinosaurs had the
capacity to grow feathers, but some didn't use it red
least once they got big, they didn't need it, which
brings us to the reason feathers might have evolved in
the first place, staying worn.
Speaker 2 (27:25):
So it's very likely that large dinosaurs, if not completely
lost their feathering, like highly reduced it. And so that's
why I brought up the analogy with the elephant. I mean,
elephant is like a big mammal, so it has to
get rid of body heat. It also lives in a
really hot place, but it hasn't completely lost its fur.
Speaker 1 (27:46):
It still has it.
Speaker 2 (27:47):
It's just very sparse. So that's why I'm just making
the argument that maybe big dinosaurs would have highly reduced
their feathering, but would they completely lose it?
Speaker 1 (27:58):
I don't know.
Speaker 2 (27:58):
Like, I can't think of any mammal that has completely
lost its hair except for aquatic ones. I don't know
if like we have had some hair somewhere, whales or hair,
that'd be so funny.
Speaker 1 (28:09):
I guess maybe a question is, what's the evolution of
those from proto feathers to the feathers we see, like
the beautiful feathers we see birds today. What was that progression?
Speaker 2 (28:18):
So I just want to give a disclaimer that the
progression from proto feather to complex fractal feather, which we
call prenaceous feathers, it's highly hypothetical.
Speaker 1 (28:30):
Gosh, we could spend a whole other episode just in this,
but here is the working hypothesis. Feathers likely evolved to
keep small animals warm, sort of like fur. You can
find this in animals dating bag to be four dinosaurs.
But then two things happened. Some dinosaurs started getting big,
and so they stopped needing this coat to stay warm,
(28:51):
which is why you only see baby pterosaurs covered in
feathers and why paleontologists think maybe baby t rexes had feathers,
but big adult ones didn't. They probably shed a lot
of it off, so no giant t rex chickens probably
And also evolution figured out feathers were also good for
other things.
Speaker 2 (29:13):
So exactation is the fancy evolutionary biology word for evolution
taking a feature that has evolved for some other reason
and then hijacking it for another function. So sinoserapter its
fuzzy little dinosaur covered in proto feathers, but tail is striped.
These feathers are not just being used for thermal regulation.
(29:35):
They're also being co opted for communication, either within a
species like hey you know wag my tail. Hey you're
also sinoserapteris what's up? Or Hey, this is my territory,
go away, you know, like just some kind of display,
some kind of communication. We really can't say.
Speaker 1 (29:50):
So that's why you see some dinosaurs with the fancy
complex feathers. They used it for mating or to intimidate
other dinosaurs, and then eventually the di dinosaurs that would
evolve in the words figured out, hey, these feathers are
also pretty good for flying.
Speaker 2 (30:08):
So for example, feathers like the fancy, panacious feathers, they
evolve for some other purpose and we're exacted for flight.
Speaker 1 (30:14):
Like I said, we could go on a whole tangent
about feathers. But to recap the main question of the episode,
did dinosaurs have feathers? The answer is yes, they all did,
and this is something we just recently found out. Does
that mean all dinosaurs looked like giant chickens? Not necessarily,
but it definitely means they're a lot fuzzier than we
(30:36):
thought before. All Right, close the episode, here's doctor McNamara.
Speaker 3 (30:42):
So that's where we are. It opens up all sorts
of ideas about where did feathers evolve? You know, are
we going to find true feathers in the early Triassic?
If that's the question we're asking, Well, these new fossils
from the Triassic tell us that in order to find
the answers for feather origins, we need to look back
(31:04):
in even all the rocks before the Triassic, And to
be honest, that's somewhere where we never thought we were
going to have to go.
Speaker 1 (31:13):
That is amazing. Last question I guess is what gets
you excited about finding the origin of feathers.
Speaker 3 (31:21):
Because they are just one of the most complex tissue
structures that vertebrates have, and because there's so much kind
of required to produce them. I just really want to
know why did vertebrates start producing these, Why did they
give us an advantage? Why did they give our deep
deep ancestors an advantage. I'm just really intrigued by it.
(31:43):
What really was driving evolution once we come on to land,
What do we do in this new environment? What are
the major challenges? You know, these are just really big
evolutionary questions, and we have the opportunity with feathers actually
to address some of that. So I just think it's
really fun.
Speaker 1 (32:03):
That's so wonderful. Well, I hope you do get a
Nobel Prize for the Professor McNamara, or at the very least,
I hope you get a feather in your cap.
Speaker 3 (32:12):
Thank you, Thank you very much.
Speaker 1 (32:15):
All right, Hey, be sure to check out my latest book,
Oliver's Great Big Universe Evolution Changes Everything. Look for it
in your favorite online or local bookstore, or go to
Great Big Universe dot Net to learn more. Thanks a lot,
See you next time you've been Listening to Science Stuff
production of iHeartRadio Britten and produced by me Or Hitcham,
(32:38):
edited by Rose Seguda, executive producer Jerry Rowland, and audio
engineer and mixer Kasey Peckram. You can follow me on
social media. Just search for PhD Comics and the name
of your favorite platform. Be sure to subscribe to sign
Stuff on the iHeartRadio app, Apple Podcasts, or wherever you
get your podcasts, and please tell your friends we'll be
back next Wednesday with another episode. Hey, if you're wondering
(33:02):
how feathers can survive the fossilization process, here's our first
ever appendix with doctor Magnamara's explanation. How do these feathers
get preserved as fossils? I thought only like bones got
preserved as fossils.
Speaker 3 (33:15):
So yeah, ninety nine times out of one hundred, you're right.
And usually when animals die, bones are the only things
that end up getting preserved. But sometimes the soft tissues
of animals and plants they don't rot away completely. In
the case of feathers, they're made of those proteins. They're
pretty tough, they're pretty robust, and they actually undergo transformations
(33:41):
when the rocks are buried and the molecules start to
link together. They form large polymers, and it turns out
that it's really hard for bacteria to destroy those polymers,
so once they start to polymerize, it actually enhances their
preservation potential.
Speaker 1 (33:59):
So some of these proteins actually survived the fossilization products
like you can see them in the rock.
Speaker 3 (34:03):
We can actually track the three dimensional architecture of the protein.
That's what's really distinctive about feather proteins is that three
dimensional corrugated shape rather than the helical shape. So we
know for a fact that some of the earliest birds
and feather dinosaurs their feathers were made of the same
(34:24):
proteins as the feathers of modern birds.
Popular Podcasts
On Purpose with Jay Shetty
I’m Jay Shetty host of On Purpose the worlds #1 Mental Health podcast and I’m so grateful you found us. I started this podcast 5 years ago to invite you into conversations and workshops that are designed to help make you happier, healthier and more healed. I believe that when you (yes you) feel seen, heard and understood you’re able to deal with relationship struggles, work challenges and life’s ups and downs with more ease and grace. I interview experts, celebrities, thought leaders and athletes so that we can grow our mindset, build better habits and uncover a side of them we’ve never seen before. New episodes every Monday and Friday. Your support means the world to me and I don’t take it for granted — click the follow button and leave a review to help us spread the love with On Purpose. I can’t wait for you to listen to your first or 500th episode!
Stuff You Should Know
If you've ever wanted to know about champagne, satanism, the Stonewall Uprising, chaos theory, LSD, El Nino, true crime and Rosa Parks, then look no further. Josh and Chuck have you covered.
The Joe Rogan Experience
The official podcast of comedian Joe Rogan.