When Birds Had Teeth - Lake Harding Association

When Birds Had Teeth

When Birds Had Teeth

By Micah Moen 100 Comments August 15, 2019


In 1861, a man working in a Bavarian quarry
discovered a fossil that would change the way we think about birds. The fossil was of a single, beautiful feather,
exquisitely preserved in limestone from the Jurassic. But the feather turned out to belong to an
animal that was unlike any other bird humans had ever seen. Nearby, the remains were found of Archaeopteryx–
a creature that by all accounts was bird-like. But it had some very weird features, like
a long bony tail and claws on its fingers. It also didn’t have the large breastbone
of modern birds. And it had … teeth. Experts are still arguing over whether Archaeopteryx
was a true bird, or a paravian dinosaur, or some other kind of dino. But regardless of
what side you’re on, how did this fascinating, bird-like animal relate to today’s birds,
like ducks, ravens, emus, that sort of thing? Well, the path from Archaeopteryx to modern
birds wasn’t a straight line. Those teeth were a clue that this story goes
all the way back to what we now call the non-avian dinosaurs. Scientists started to realize that birds actually
are dinosaurs not long after Archaeopteryx was discovered in the 1860s and 70s. That’s because, around the same time as
that find, another discovery was made in those same Bavarian quarries. It was the skeleton of a tiny meat-eating
dinosaur called Compsognathus And it was the first more-or-less complete
skeleton of any dinosaur ever found. Compsognathus had a lot of traits that seemed
bird-like — it had a curved neck, it stood on two legs, and it had three main toes. And
we now think it might’ve even had hair-like feathers. But it was indisputably not a bird. It had
very short arms instead of wings. And it had a pelvic bone, called the pubis, that pointed
forward instead of backward, as it does in birds. So Compsognathus was a non-avian dinosaur
that looked kind of like a bird. Then, in the 1870s, American paleontologist
O. C. Marsh described two more species that illuminated the transition between dinosaurs
and birds, found in late Cretaceous rocks from Kansas. One was Ichthyornis, which looked pretty much
like a seagull. And the other was Hesperornis, which resembled a huge, flightless loon. Ichthyornis was clearly avian — it had wings
without claws, a short tail, and a large breastbone, like most modern birds do. But both it and
Hesperornis also had teeth, like most non-avian theropods did. So, Marsh and other experts began to hypothesize
that birds evolved from dinosaurs. In these specimens, Marsh saw how birds gradually
acquired their curved necks, their two-legged stance, and their three toes. He saw modified arms transition to feathered
wings, and the loss of claws and the long tail. Hesperornis and Ichthyornis were soon classified
as ornithurines, a group of Mesozoic birds whose names means “bird tail.” These ancient birds had short tails, instead
of the longer bony tail of Archaeopteryx. Most of them also had teeth. And they tended
to live on the ground. We know this because they were usually found
in environments near shorelines, instead of inland forests, and they didn’t have the
adaptations that are associated with perching, like curved foot claws, or claws on their
wings. So by the late 1800s, many scientists believed
that it was this group, the ornithurines, that gave rise to today’s birds. They didn’t
know what happened to their teeth, but they knew the connection was there. But still, not everyone was convinced that
birds derived from dinosaurs at all. In the early 20th century, some researchers
— led by Danish paleo-artist Gerhard Heilmann — argued that the similarities between Compsognathus
and birds were convergent, and that birds evolved from some other, mystery reptile. It wasn’t until 1970 that, quite by accident,
paleontologist John Ostrom came across the key that would unlock the origin of birds. He was studying fossils of pterosaurs from
the same German limestones that produced Archaeopteryx and Compsognathus. But one of these fossils was not from a pterosaur,
as many had thought. It turned out to be the hand of an animal that was very similar to
Archaeopteryx. Actually, for a long time, Ostrom and others
thought it was an Archaeopteryx. But in 2017, it was redescribed and assigned to a new genus,
named after Ostrom himself. Now, the hand of this animal looked just like
the hand of a non-avian dinosaur that Ostrom had uncovered just a few years earlier in
Montana, called Deinonychus. Both animals had short thumbs, long second
fingers, and third fingers of medium length. And in both specimens, most bones in the wrist
were fused together into a half-moon shaped block that allowed for movement from side
to side, but not up and down. Living birds have this same half-moon feature
in their wrists, which they use to fold their wings. So, Ostrom’s discovery revived the theory
that birds evolved from small theropod dinosaurs. And yet, we had no idea how incomplete our
understanding was, until the 1980s and 90s, when dozens of new fossil discoveries showed
us how truly diverse birds were in the Mesozoic. Most of the fossils found around this time
belonged to a whole new lineage of extinct birds that we didn’t know existed. They
came to be called the enantiornithines or “opposite birds.” Which is a terrible name, because they totally
were birds. They were only called opposite birds because one of their shoulder joints
was the reverse of what’s seen in living birds. But, unlike the ornithurines, which mostly
lived on the ground, these opposite birds mostly lived in trees. Their fossils were
commonly found in rocks that formed in ancient forests, and most of them had curved claws
like perching birds do today. And these turned out to be the most common
and diverse group of birds in the whole Mesozoic era, filling many of the same roles as modern
birds. For example, Bohaiornis may have hunted small
vertebrates 120 million years ago in ancient China. And it lived alongside Longipteryx, a perching
bird with a long snout that may have dove for fish from tree branches, like kingfishers
do today. Most of these opposite birds had teeth and
clawed fingers. And instead of having a fan of feathers in their tails, they had blunt
rear-ends that sometimes sported just two long, ribbon-like feathers. So it was clear to scientists that these “opposite
birds” belonged to a different lineage than the likes of Hesperornis, Ichthyornis, and
the other ornithurines. Meanwhile, experts were also making some important
discoveries about the ornithurines, too. Especially, what happened to their teeth. For example, in the early 2000s, Chinese researchers
reported finding the oldest fossil evidence of a toothless bird. They named it Confuciusornis,
and it lived 130 million years ago — way back in the early Cretaceous. And the strangest thing was: Confuciusornis
was neither an ornithurine nor an enantiornithine. It turned out that toothlessness was a convergent
trait that showed up in lots of different groups at different times. Some opposite birds didn’t have teeth, and
some early ornithurines didn’t either. So, where did their teeth go? Well, for a long time, scientists thought
that birds lost their teeth to make their bodies lighter. But now we know that some
toothed birds were able to fly, so it wasn’t like having teeth was keeping them on the
ground. As more fossils of Mesozoic birds were found,
more clues started to present themselves. For instance, experts began to notice that,
even though most ancient birds had teeth, they tended to have fewer teeth than their
dinosaur ancestors. And fossils also revealed that birds started
to have fewer teeth after they developed gizzards. Gizzards are a muscular part of the stomach
where, with the help of swallowed pebbles, birds can grind up their food. So with the
advent of gizzards at least 120 million years ago, the need for teeth started to fade. And as birds’ teeth changed, so did their
beaks. Most opposite birds retained teeth at the
very front of their mouths. But in ornithurines this same area became covered in keratinous
beak tissue, while they kept the teeth that were farther back in their jaws. Now, some experts think that replacing teeth
with beak tissue may have had something to do with making it easier to eat certain foods,
like seeds. But another theory, proposed in 2018, suggests
that beaks may have been more advantageous for baby birds. Teeth take a long time to grow in developing
embryos, but if you shorten that step or cut it out altogether, then eggs can hatch earlier.
And the shorter a bird’s incubation time is, the less vulnerable its young will be
to predators. So birds may have lost their teeth for many
reasons. But one thing we know for sure is that, in the Cretaceous, teeth disappeared
in the group of ornithurines that would give rise to today’s birds. These are the neornithines. Their fossils are still very rare, but in
the past couple of decades, paleontologists have found bones of the very earliest members
of this group. One of the best known is a 68 million year
old duck relative from Antarctica called Vegavis. And its remains show that, even by the Late
Cretaceous, it was already well adapted to swimming and diving. So today, we finally have enough fossils of
different kinds of birds to know that, about 66 million years ago, there were both toothed
birds and toothless birds from many different groups. And generally, they were all doing
just fine. Until, the Cretaceous Period ended in extinction. There were many causes behind the extinction
event that killed off the non-avian dinosaurs. But when it came to birds – and most everything
else – , the worst was probably the asteroid impact in the Gulf of Mexico. The impact set off huge fires that destroyed
entire forests and vaulted dust into the atmosphere, probably blocking much of the sunlight for
years. For birds, their odds of survival might have
come down to a number of factors, including how big they were, where they lived, and what
they ate. For example, if you lived in trees, like most
opposite birds did, you were in the worst possible place in the aftermath of the impact. Not only was your habitat suddenly gone, but
if you ate plants, it would be weeks or months before any new growth would be available.
And if you ate meat, there was almost nothing around to hunt. But if you were smaller and lived on the forest
floor, there’s a chance you could have found shelter. And it might’ve been a lot easier
for you to find food, like seeds on the ground. Likewise, if you were aquatic, your habitat
and your food supply, might have been less disturbed by the fires. So, out of what may have been thousands of
species of dinosaurs living at the end of the Cretaceous, only three groups of neornithes
had that perfect survivor’s combination of being small, ground-dwelling or aquatic,
and seed-eating. One of these lineages was the paleognathes,
which today include ratites like ostriches and emus, as well as weird South American
birds called tinamous. The galloanserans also survived, like Vegavis
and its kin, possibly thanks to their aquatic lifestyle. Today they include chickens, ducks
and other kinds of fowl. And the third lineage is the neoavians, which
includes essentially every other living bird. Free of competition from the tree-dwelling
opposite birds, a lot of neoavians quickly took to life in trees at the dawn of the Cenozoic. These birds all have diverse diets and habitats
today. But by analyzing the earliest known members of each group, scientists have found
that the last common ancestor of all living birds was indeed a ground-dwelling seed-eater. Each of these three lineages might have had
only a handful of species at the time of the extinction, but they are the ancestors of
the roughly 10,000 species of birds that are alive today. There are many things we have yet to learn
about the story of birds. But our understanding has grown tremendously since that lovely fossil
of a feather was first discovered in Germany, more than 150 years ago. And, just within my own lifetime, a wealth
of bird fossils has been discovered that are only beginning to reveal the wonderfully weird
and diverse world of the Mesozoic, when birds had teeth. I hope you enjoyed this toothsome episode and all the difficult words I had to say. Now,
here’s something new for you! “ReInventors” is a new show from PBS Digital
Studios and KCTS9 in Seattle that will introduce you to scientists and inventors on the cutting
edge of green technology. They’ll eat edible plastic, so you don’t have to, and take
you to unexpected places, like a garage that has its own nuclear reactor. Check out ReInventors
and subscribe to them at the link below. And of course, don’t forget to let me know
what you want to learn about, and if you haven’t already, go to youtube.com/eons and subscribe And we want to thank our two eontologists, David Reed Rasmussen and Steve. Thank you so much for your support! If you’d like to join them, head over to patreon.com/eons and pledge for some neat n nerdy rewards.

100 Comments found

User

OPT X

What about pelagornis didnt they have teeth

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User

Petitio Principii

Such a relaxing voice/narration. I think she could say something gruesome and terrifying like Alan Grant said to that kid in Jurassic Park, about how Velociraptors would rip his guts and eat him before he was even dead, and it wouldn't elevate my heart rhythm in the least. Even if it instead of Velociraptors, cassowaries were mentioned.

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User

Petitio Principii

There were also several birds with fake teeth, indentations on their bony jaws. And there's also some sort of teeth imitations some birds have on their tongues, and if I'm not mistaken some also have hard indentations made of the "soft tissue" of their beaks.

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User

Gyara

Love these flying dinosaurs.

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User

Quazimodo Oak

bird up

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User

gromann

This is quickly becoming my favorite channel..

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Flavius Nita

So teeth were to heavy to fly, but pebbles in stomach not…

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User

Alp

good video, may be 10 oldest animal species on Earth aquatic and not aquatic 🙂 and you can explain how they survived

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User

Joseph Brunetti

Hey I would really love to meet eontolgist In a video so I could put a face to the name of these people who are helping your channel so much

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User

Marie Jones

do penguins

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User

Christian Hall

Geese have teeth 😐

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User

Glarder

But geese still do.

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User

UnceasingNoise

Anyone else just want to hear this lady talk about animals all day! She has such a comforting voice while describing evolutionary biology

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J Cortese

Still thinking about this topic because I'm an obsessive … I suppose beaks are the reptile analogue to horns on mammals — keratin-covered bony processes. But being warm-blooded, maybe eating things that require beaks (seeds, insects) doesn't allow us to get enough calories into us, so beaks never developed in mammals?

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Genghis Don

amazing

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User

PostHumanOriented 8472-1488

Talk about the evolution of the immune system

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User

Kredenc

Wait a moment, correct me if I'm wrong but when they were talking about bird wrists, wasn't a knuckle actually circled and not the wrist? Because from what I've seen, the joint of metacarpals and phalanges was circled (?)

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User

Kirla

And when the birds die, bats will be ready to rule the world.

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nocturnal nerdy nadine

The amount of words this woman had to pronounce correctly, all in a row, is SO ASTOUNDING

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User

Tony Montana

othniel marsh and edward cope the bone wars

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User

walamander playz

But wait trisarotops is a dinosaur and it doesn't seem to be a bird so that prove that not all dinosaurs are birds

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User

feh meh

Why could it have not happened more than once covergently? Flght traits a select for pretty strongly, so much that you can compare pterosaurs with bats. Why so strange that two dinos became birds?

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User

Darth Belal

Permian proto/stem mammals please!

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User

Ben Pace

So did birds have to relearn how to fly?

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User

Jennifer Isaacs

Technically there are serrated beaks with moderns bird is teeth like.

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User

Nicholas Y

this is such an amazing video <3

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User

KevinPlayz

I saw the title and instantly said "So the mesozoic?"

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R P

Don't geese still have teeth?

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User

Yassin Younis

How about a video of what would evolving show us from now

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User

mushnoodle

Can we have one about how communication developed? Visual too but if possible verbal etc i kinda think it might also be interessting to know not just how the past looked like but how it sounded like ^^

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carlo formosa

Fight milk!

2:24

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JoeF.

Best channel on YouTube !

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Vercil Juan

Please make one on argentavis

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Wesley Mcspadden

So did Pterosaurs who ate fish went extinct because they suffocated, because in this video you said that birds who ate fish had enough food to eat but pterosaurs ate fish too. was it because there size was to big to get enough food or was it because most Pterosaurs lived in higher elevations and any ash that was still in the air during the meteor impact or from a volcanic eruption suffocated them Im just curious.

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User

How Much For A Gram

What is up with all the pebbles from the bird stomach being quartz variants (agate/chalcedony)? Less biologically reactive? Just because they are shiny?

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Ivy Whooo

Reminds me of Tokoyami

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Steven Ruppe

Fantastic; you all are really getting the swing of this down pat.

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squid din

I dont know about you but that image with two aquatic birds and and partially aquatic pterosaur is pretty dope.

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Tomek Triceratops

Aren't the paleognathes birds a sperate group form the neornithine birds.

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Ebi Toro

I like how this presenter seems to wear different brooches related to the subject

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Josh Mitchell

Small nitpick here. You said that a theory was proposed, but theories aren't proposed. That's hypotheses. Theories are conclusions arrived at and agreed upon by many scientists independently.

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der Lean

Imagine how many fossils just weren't discovered or just not seen.

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Holbein Crâne

Mammals: 5400 known species
Birds: 9990 known species

Conclusion: We're still on the world of the dinosaurs!

(well, at least we're more on theirs than on ours)

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User

es6416 5

I hate ichtyisornis

Who else plays ark

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Che TheLion

But I picked up baby bird before and it had teeth…idk what species it was but it had teeth.

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Smoked

Charlie was right all along

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User

Mairaine Playzgames

ichthyornis is an incredibly annoying bird if you play Ark: survival evolved…diving down and stealing your stuff…

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User

xl

What kind of body type does the human female host have in this video ?

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User

u235u235u235

love the nails.

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XMattingly

7:07 Hell, yeah 👌

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User

Dogs For Arms

I think this channel is the best thing I have ever found on YouTube. I would love to learn more about cephlapod history, really early ones like orthocerida are kind of surreal seeming to me.

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Michael Daniels

I find it interesting that for the longest time Christians claimed that humans and dinosaurs lived at the same time, and the scientific community said that we didn't. But now Christians have gotten with the idea that we didn't, but the scientific community is now basically saying that birds are dinosaurs, so humans and(at least one variety of) dinosaurs did and do live at the same time.

Not hating on Christians, I am one. I just thought it was interesting.

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User

KamiSam

Some of these tooth birds are derpy as hell 😂

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Doctor Demonetized

I feel like if we call Birds Dinosaurs or Dinosaurs birds, then we should be calling Dimetrodon a mammal. Dinosaurs and species like Dimetrodon were similar in that they were a transition from Reptile to their respective families. Dinosaurs shared a lot in common with birds, but also a lot with their reptilian ancestors, and the same goes for Dimetrodon with Mammals. I dunno, taxonomy can get convoluted very fast.

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Seiyuōkami Himura

Ornithology anyone?

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Eli Burry-Schnepp

I personally don't think that anything outside of Aves is a true bird, just a very birdlike dinosaur, since they aren't descended from the common ancestor of modern birds. It's really just pedantic, since "bird" isnt really a scientific classification, but it's my interpretation.

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Because I'm a fan

Cuteness alert @ 7:47!! So adorable!!
Excellent video, as always! ♥️

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Justin Steiger

I love PBS Eons! The best ones are the ones with Kallie hosting, her accent/way of talking is relaxing.

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SecretxOfficial

Aviary=Jurassic Park

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Jim Mauch

It’s interesting to see that the future of our avian dinosaurs would result in their developing gizzards, loosing teeth and evolving keratin beaks. It’s those little changes you can believe in.

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Hans Günther

How did birds survive the meteor? I mean mammals were under earth, crocodiles probobly too or in deep swamps, but birds are very fragile

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Here's Hot Rod

This why I can't stand people like Ken Ham or Frank Turk. They know nothing about evolution, but yet talk about it and fail to debunk it. They think that evolution is animal popping out of nowhere. That's creation not evolution. Evolution is the why and not the how.

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User

keahistight

What is the narrators name and educational background? Is she in the same league as Hank and John Green from Crash Course or Dr. Joe Hanson from it’s OK to be Smart? Just wondering because I love your content.

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User

Darkvine

Evolving a gizzard that needs to be filled with rocks doesn't seem a very logical thing to do while evolving to become lighter for better flight 🤔

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HungerGamesFan88

ARE THOSE DUCKLINGS? I'LL TAKE 20

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Matthew Chenault

66 million year old birb: B E E P.

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Marko Sabljak

I hate these images of archaeopteryx that shows them as monsters with 10 feathers.

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0192123

10:15 wait… Galloanserans which were semi-aquatic include ducks and chickens!? are you telling me ancient chickens used to be aquatic?! please PBS Eons explain this!

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Haram PorkDick

I dont know why this is still "controversial" embryonic modern birds have teeth, and a tail, they loose these features later on the embryonic stage and this is due to genes that influence their embryonic development.

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Frenchie 11

My pet chicken eats dog food! and is pretty feisty, she chases the dog!

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Alice Willoughby

I know this video isn't about hair, but I've got to say, I love your braid!
This video is really fascinating! The variety of birds and pre-birds is really amazing!

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George A Learned Jr

I really like this Lady teacher, she does a great job explaining the facts!

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Nick Sloan

Ah, so dino nuggets aren't too inaccurate after all! In fact, I guess technically ALL chicken nuggets are dino nuggets.

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User

Homer's Iliad

THIS ONE IS FOR CHARLIE FROM IT'S ALWAYS SUNNY IN PHILADELPHIA.

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ZyroIzMvp

Been watching this channel for nearly a year and just now thought to subscribe, and i have no idea why..

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Gillian Patton

My pet chicken had a tiny claw hidden in her wing feathers. It was hard to find but it was there.

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Dan

4:56 i like her curves in jeans

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Cal Sheridan

Opposite birds… so… Dribs?

"Dribs".

These are "dribs".

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plopidrahtis

birds are tinysaurs

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Aaron Marks

Can you guys do a video on the Hoatzin? It's an Amazonian bird that still has wing claws

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Jacob Masten

I’m a Bird

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Jacob Masten

I remember when birds had teeth

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Blobbert Mcblob

Some birds like Turkeys, chickens and waterfowl still have a single small claw on the ends of their wings.

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Marina Biritz

Ducks , geese, and swans still actually have teeth.

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thefisherman007

When ur a lover of dinosaurs but hate birds cause they steal ur bait.

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George Dorrance

It makes more sense to have beaks you can cut me in a smaller slivers allowing it to digest better allowing you to have more calories to spend more energy

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jay savage

how come birds have the back claw and the no feathers to feathers

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jay savage

And I think lizards are closer to Dino’s u have them bigger and walk on two legs their u go

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Sun Jara

6:46 XD Teeth aren't that heavy! LOL

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Kanthor

THEY ALREADY DID BIRDS WITH TEETH!!!!!

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Melvorgazh

Birds ARE Dinos

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Alexander Schumacher

So, dinosaur shaped chicken nuggets . . .
Are made from dinosaurs?

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GregoryTheGr8ster

Is she reading from a teleprompter, or does she really know all this stuff?

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Roy Barron

Bird up :p

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The Fox

I wish somebody made a video about parrot evolution. Everything about them is just so interesting.

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bizotically_yours83

I introduce you to modern day geese.

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King Bora Beats

They look like goof balls with teeths 😂

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Arun Lazer

Your videos are too lengthy …Please concentrate on the title …..

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Richard Adams

My cockatiel, Baby, says thank you for making a video about his grandparents.

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User

reed

Now imagine if Seagulls have teeth and you are eating. Lmao.

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