00:00So, check out this creature.
00:03What do you think this thing is?
00:04Is it a plant, an animal, or maybe even some kind of wild fungus?
00:09At first glance, this fossil could pass for any of those ancient life forms.
00:13And honestly, scientists have been scratching their heads over it for over 150 years.
00:19But now, it looks like we might finally be cracking the case on this unknown species discovery.
00:25A long time ago, during the Devonian period, plants were just starting to grow on land.
00:31The tallest trees were only a few feet height, and animals hadn't even evolved backbones yet.
00:37Back then, massive natural towers up to 26 feet tall and 3 feet wide,
00:42looking like branchless cylindrical tree trunks, were rising from the ground.
00:47Hey, what a contrast with trees back then.
00:50When scientists first discovered fossils of those towering organisms,
00:53they were totally confused, as these strange, prehistoric creatures
00:57didn't look like anything they'd seen before.
01:01Some thought they were weird, cone-bearing trees.
01:04Others guessed they might be underwater plants, like giant seaweed or lichens,
01:09which are partnerships between fungi and algae.
01:12The mysterious objects received a name, prototaxetes.
01:17When scientists studied them up close,
01:19their internal structure reminded them of a bunch of different things.
01:22They couldn't believe a 20-foot-tall fungus or algae could be real.
01:27But that's what the fossils showed.
01:29Then, most scientists decided that prototaxetes were giant fungi.
01:33But still, something didn't feel right about it.
01:37In 2007, they decided to finally get the prototaxetes mystery explained
01:42and ran a chemical test on the fossils.
01:45So, they looked at the types of carbon inside them
01:48and compared them to regular plants from the same time.
01:51If prototaxetes were plants, the carbon ratios would match.
01:56But they didn't.
01:57That means prototaxetes weren't plants.
02:00And they received carbon in a different way,
02:02not by photosynthesis, but probably more like fungi do.
02:06But then again, they looked nothing like the mushrooms we know and love today.
02:10Prototaxetes were giant,
02:12likely the largest living things on land at their time.
02:15And even if these strange, prehistoric creatures were some fungi of their sort,
02:20then it's weird they don't have any living relatives today that would resemble them.
02:25So, if we put all this together,
02:27it looks like prototaxetes are an entirely different
02:30and previously unknown life form that didn't leave any offspring.
02:36Prototaxetes aren't the only unclassified organisms on Earth.
02:40About 600 million years ago, there were no fish, no sharks, no crabs.
02:46Just simple life forms like algae and bacteria drifting through calm, shallow seas.
02:51But some seriously strange creatures,
02:54completely unlike anything we see today, lived among them.
02:57They looked like underwater ferns,
03:00stood perfectly still, and absorbed nutrients straight from the water.
03:03These bizarre life forms were rangiomorphs.
03:07They ruled the oceans that were thick with nutrients back then.
03:10So, rangiomorphs didn't need mouths, eyes, or muscles to survive,
03:15and just soaked up whatever they needed.
03:17Some of them were as small as a finger,
03:19and others grew as tall as 6 1⁄2 feet.
03:24But as Earth entered the Cambrian period,
03:27the oceans became much more competitive.
03:28Fast-swimming creatures with limbs, eyes, and jaws showed up,
03:33and ate the same food faster,
03:35and maybe even ate the rangiomorphs themselves.
03:38The chemistry of the oceans also started to shift.
03:42And the nutrient-rich waters became more like today's oceans,
03:45where food floats around in particles that active animals scoop up.
03:50So, the rangiomorphs vanished forever.
03:53But scientists still find their fossils all over the world,
03:56preserved in ancient rock.
03:57They had an incredible fractal design,
04:00a pattern that repeated itself at every level,
04:03from the smallest branches to the full body.
04:06Using fossil clues,
04:07researchers built 3D computer models of what rangiomorphs looked like.
04:12They found out that these strange prehistoric creatures
04:15filled their space in a nearly perfect way.
04:18They were like optimized living sponges.
04:21But scientists still can't agree on where exactly rangiomorphs fit on the tree of life.
04:26At first, they argued over whether they were plants,
04:29animals, fungi, or something completely different.
04:33Now, most agree they were primitive animals,
04:35though they were so different that they might deserve their own unique branch,
04:39which scientists call a clade.
04:41And then there was Dickinsonia, another prehistoric creature that was so strange
04:48that scientists couldn't even agree on what it was for nearly a hundred years.
04:53Some thought it was a giant single-celled amoeba.
04:56Others thought it was a type of lichen, or maybe a failed evolutionary experiment.
05:01This bizarre life form lived about 558 million years ago,
05:05long before dinosaurs, sharks, or even insects showed up.
05:10After many years of studies, Australian researchers finally got proof
05:14that Dickinsonia was an animal,
05:16and possibly the oldest one scientists have ever found.
05:20They solved the mystery thanks to really well-preserved fossil fat molecules
05:25stuck in the rock near the White Sea.
05:27These molecules were a type of cholesterol,
05:30the kind of fat found in animal cells.
05:32If cholesterol is present, it almost certainly came from an animal.
05:37Sort of like animal DNA.
05:39Dickinsonia lived millions of years earlier than scientists had previously thought,
05:43and didn't look anything like modern animals.
05:46It had no head, no mouth, no arms, no legs, and definitely no organs.
05:52It was oval-shaped, like a giant pill bug or flattened jelly bean,
05:56with weird ridges running across its body.
05:59Some were tiny, but others grew up to 5 feet long,
06:02the size of a person.
06:04It didn't swim or walk, but was just lying on the seafloor,
06:07soaking up nutrients from the water, or absorbing stuff through its skin.
06:12It was tricky to identify because most fossils came from high-pressure rock,
06:16where heat had destroyed all the delicate organic stuff scientists needed to study.
06:21To get to the good fossils, researchers had to rappel down 300-foot cliffs,
06:26dig out huge blocks of sandstone, throw them down, wash them,
06:30and then repeat the process.
06:32And inside, one of those sandstone slabs was the fossil that changed everything.
06:38That helped finally confirm that Dickinsonia was an animal,
06:42which proves that complex animal life existed before the Cambrian diversification,
06:47where tons of new animals with bones, eyes, and limbs suddenly appeared.
06:53Scientists think the spot where they found these fossils
06:55might hold more clues about ancient life.
06:59For a long time, scientists had no clue what other group of ancient life forms,
07:04slime molds, were.
07:06These weird jelly-like blobs that pulse and ooze on rotten logs and forest floors
07:11aren't fungi-like mushrooms, though people thought they were for years.
07:15It turns out they're more like amoebas,
07:18squishy, single-celled organisms that can move around.
07:21There are over 900 species of slime molds all over the world.
07:26You'll find them in soil, leaf litter, and especially on decaying wood.
07:31Scientists found them trapped in amber from 100 million years ago.
07:35And it looks just like modern slime molds.
07:38Scientists still know very little about how slime molds interact with other species,
07:43what role they play in ecosystems,
07:45or how they think without a brain, nerves, or a control center.
07:49But, somehow, they can make decisions and adapt to their surroundings.
07:54It makes them a lot like social insects, like ants or bees,
07:58where no single bug is in charge,
08:00but the colony still works together as a smart group.
08:03Even without brains, scientists have trained slime molds to solve mazes
08:08just by responding to chemicals and learning from their environment.
08:12One way these organisms learn is through a process called habituation.
08:16It's sort of like how you get used to cold water after jumping in a lake
08:20or stop noticing an annoying buzzing noise after a few minutes.
08:24That's your brain helping you tune out something harmless.
08:27Some slime molds can do this too.
08:30If they get in nasty conditions, like salty, dry, acidic environments or chemicals,
08:35they'll avoid them at first.
08:37But if there's food on the other side,
08:39they'll eventually get used to it and push their way through.
08:42And if you let slime mold go dormant and wake up a year later,
08:47it still remembers how to deal with salt.
08:50They even seem to be able to decide where to go
08:53based on where they found food in the past.
08:56With more and more unknown species discoveries,
08:59scientists can paint a better picture of Earth's biological past.
09:03That's it for today.
09:07So hey, if you pacified your curiosity,
09:10then give the video a like and share it with your friends.
09:12Or if you want more, just click on these videos and stay on the bright side.
Comments