Hi, welcome to Mental Floss on YouTube.
I’m Emily Graslie of The Brain Scoop sitting
in the Chicago Field Museum and today we’re
going to talk about some mind-blowing and
unfortunately (and sometimes not so unfortunately)
extinct lifeforms
It wouldn’t be right to start talking about
anything but the earliest evidence of life
itself, which are layered structures called
stromatolites.
Stromatolites occurred when early bacteria
and microbial life formed mats that turned
into sedimentation on the bottom of the ocean
some 3.5 billion years ago.
So, life began! but not a lot else happened
for the next 3 billion years, so let’s fast-forward
to
Trilobites.
These early arthropods - aka invertebrates
with hard bodies, like our modern-day lobsters
and spiders - are some of the most diverse
forms of early life on the planet.
Trilobites were around for hundreds of millions
of years; from about 521 million years ago
to up to 250 million years ago before they
all died out in the Permian mass extinction.
But we know of more than 20,000 different
species of trilobites today!
To start off a list of ‘things that I am
pretty glad no longer exist’ are the Eurypterids,
which were giant sea scorpions.
And we’re talking about invertebrates that
were around 8 feet or 2.5 meters in length
- that’s the size of a crocodile.
These predatory cannibals show up in the fossil
record about 460 million years ago and [thankfully]
died off around 248ma.
It wouldn’t be right to glorify history,
so let’s talk about how some early lifeforms
subsisted: like this poop-eating snail.
This early gastropod from the Silurian period
existed about 443-419 million years ago.
And when there’s not a lot of food around
you[a] go to what’s reliable, in this case,
feces.
This early mollusk has been fossilized attached
to the anal end of a crinoid - a simple kind
of animal that looks and acts like a plant.
And here it shall forever be frozen in time,
as evidence of its dirty poop-eating habits.
The Dunkleosteus [Dunkle + osteus] was one
of the largest plate-skinned, armored fishes
ever to live, and it swam around 380-360 million
years ago.
Scientists here at the Field Museum have concluded
that it had a bite force comparable to that
of T. rex and our modern-day crocodiles.
It would’ve used up to 1,100 pounds of force
and closed its mouth so quickly that it would
have created suction in order to draw in its
prey and oh my god I’m so glad they don’t
exist anymore.
[b]
Another ancient ancestor we owe a lot to is
Tiktaalik (tick-ta-leck), also known as “fishapod”.
This ingenious creature serves as a turning
point in the evolution of life because at
about 375 million years ago it learned how
to walk onto land.
This ultimate grandfather of tetrapods was
half fish and half amphibian, and there is
evidence that it had gills as well as lungs.
If we’re going to be talking about early
life I have to make a mention of the Tully
Monster.
This unique soft-bodied invertebrate lived
about 300 million years ago and so far is
unique to the Illinois region, so naturally
they went ahead and made it the state fossil.
The Tully Monster is unique because of its
weird, cuttlefish like tail, its proboscis
with teeth and its adorable, protruding little
eyeballs.
Edaphosaurus, which you may recognize, was
an early synapsid, which is kind of like an
early mammal-like reptile.
They existed around 303-275 million years
ago and are most notable for their gigantic
vertebral spine.
Unique to Edaphosaurus are the crossbars on
these spines.
Nobody can quite make up their minds what
they were used for, and debates arise on whether
or not they were used for food storage or
thermoregulatory reasons.
Another animal I’m increasingly glad no
longer exists is the Helicoprion (hell-ih-cop-reeon)
an ancient shark from the early Triassic that
lived around 250 million years ago.
Not much is known about this terrifying creature
other than instead of normal teeth it essentially
had a circular saw growing out of its mandible.
Scientists refer to this as a “tooth whorl”
and provided a never-ending cycle of permanent
teeth.
We couldn’t very easily have a list about
mind-blowing now-extinct lifeforms without
at least giving a nod to the, Tyrannosaurus
rex - specifically this lady behind me, who
is the largest and most complete example of
her species ever to be discovered, making
her one of the largest land predators to ever
walk the planet.
You can’t tell me that isn’t mind-blowing.
On the subject of unbelievably gigantic predators,
we can’t help but talk about the pterosaur,
especially this one, Quetzalcoatlus, which
stood as tall as a giraffe and had a wingspan
up to forty feet.
As previously mentioned in the 50 common science
misconceptions video, pterosaurs were lizards,
not dinosaurs or birds, thus becoming the
closest living thing to a dragon as ever existed.
Fast forwarding in time we’ve got weirdos
like Interatherium, a moderately-sized grazing
animal that has hooves but looks like a squirrel
and roamed the prairies around 65-33 million
years ago.
Rodhocetus was a carnivorous mammal from about
40 million years ago.
Fossil evidence suggests that this animal
was able to move between land and water.
It had a fused pelvis and mobile leg bones.
Scientists know that modern whales are closely
related to artiodactyls; even-toed ungulates
like deer.
You may have also heard of terror birds, and
I’m sure from the name you can imagine the
implications.
These apex predators roamed the planet from
62-2 million years ago and many of them stood
between 3-9 feet tall.
They were flightless but this loss of mobility
only seemed to motivate them to become as
intimidating as possible - at least superficially.
It’s actually thought that, depending on
the species, they subsisted mostly off of
small rodents and lizards.
Another well-known but classic relative of
our collective past is Australopithecus afarensis,
like our friend Lucy here, looking stunning
at a ripe old age of 3.2 million years old.
A. afarensis survived on our planet for more
than 900,000 years, which, at this point,
is more than 4 times as long as our own species
has been around.
But at least we have pizza delivery.
If you’ve ever been curious about the difference
between a Mammoth and a Mastodon, then the
easiest way to tell is by taking a look at
their teeth.
Mammoths have teeth like our modern-day elephants
- but the teeth of a Mastodon have high peaks
and ridges, which makes sense because ‘mastodon’
is Greek for “breast/nipple tooth”.
We were still hunting and eating these guys
up until about 10,000 years ago.
Another notable and difficult to ignore Ice
Age mammal is Megatherium, the giant ground
sloth.
I bring these guys up because they are one
of the largest land mammals to ever live and
we are still feeling the negative effects
of their extinction today.
Big animals mean big poop, so the sudden decrease
in distributed fecal matter means there’s
a lack of nutrients in the soil, like phosphorus,
which help to promote healthy forest growth.
The Irish Elk is another one of these giant
Ice Age megafauna to disappear from about
11k years ago, although it’s not entirely
certain if it was due to climate change or
overhunting by that pesky species Homo sapiens.
Irish elk is bit of a misnomer since they
were still found in parts of North America
and they compare more favorably to deer than
elk.
But, true to their megafauna nature, they
had racks that measured up to 12 feet across.[c]
The passenger pigeon is worth noting because
of the sheer improbability of its extinction.
It was the most abundant bird species to ever
exist and gigantic flocks would sometimes
take 14 hours to pass overhead, their feces
raining down like snow.
Because of the European invasion of North
America and our insatiable urge to fire off
bullets into large herds of animals, the passenger
pigeon was considered extinct in 1914.
The pig-footed bandicoot is the cutest marsupial
to ever have walked on one hoof.
It had cloven hooves in the front and a single,
elongated toe in the back.
A 19th-century naturalist described its locomotion
like “a broken-down hack in a canter, apparently
dragging its hindquarters behind it.”
The poor bandicoot was considered extinct
in the 1950s after over-farming in Australia.
Even though they’re gone, scientists are
trying to bring back the recently extinct
gastric brooding frog.
There are only two known species ever to exist
- they were discovered in the 1970s and gone
by the 1980s - but they are the only known
animal to ever give birth through their mouths.
And it’s hard to say because it’s hard
to believe.
The female would swallow her recently-laid
eggs and then keep them in her stomach until
they were fully developed.
And then, when they were ready to come out,
she would forcibly vomit them all out at once
- sometimes up to 26 at a time.
Thanks for watching Mental Floss on YouTube,
which is made with all the help of all these
nice people and super huge awesome thanks
to Bill Stanley, Alan Resetar, Paul Mayer,
Jim Boone, the Harris Learning Collection,
and everyone else at the Chicago Field Museum.
Every week we endeavor to answer one of your
mind-blowing questions and this week’s question
comes from Lily K., who asks, “Is it true
you have to wait a half hour after eating
before you go swimming?”
It is an old wives’ tale that you will get
a cramp and drown if you go swimming immediately
after eating, but maybe you should just give
yourself a little break anyway.
If you’ve got a mind-blowing question that
you would like to see answered, be sure to
leave it in the comments below.
I’m Emily Graslie of The Brain Scoop, and
don’t forget to be awesome.
