The Extinction That Never Happened

Video Statistics and Information

Video
Captions Word Cloud
Captions
This episode is supported by Squarespace If horror movies have taught us anything, it’s that the dead have this knack for coming back from the grave and showing up again to freak us out. And in a way, the same can be said for some fossil animals. Natural history is full of things that were long thought to have gone extinct only to show up again, alive and well. Paleontologists have a word for these kinds of organisms: They call them Lazarus taxa. These taxa get the reputation for being well, dead because their remains suddenly disappear from the fossil record, making it look like they’ve vanished, even though they’ve stayed around, often for millions of years. But, aside from blowing our minds by re-appearing when we least expect it, Lazarus taxa give us a fascinating lesson in the limits of what the fossil record can really tell us. One of the most famous stories of life returning from the depths of time starts over half a billion years ago, in the Cambrian Period, right when life was getting its feet under it. Literally. Even though life originated on Earth about 3.8 billion years ago, for most of Earth’s history, the story of Life was a story of single cells. Multi-cellular life didn’t show up until about 900 million years ago, and the first squishy things we can call the earliest animals only appeared about 100 million years after that. So, animals are still the new kids on the block. But by 508 million years ago, during the height of the Cambrian, the Animal kingdom was running riot. And there’s no better place to see the evidence of this, than in the gray stone of British Columbia’s Burgess Shale. Discovered by paleontologist Charles Walcott in 1909, the Burgess Shale is a fossil wonderland brimming with creatures so amazing, and so confusing, that for decades scientists couldn’t figure out even the most basic information about them -- like which part of the animal was the top, and which was the bottom. But over the past century, experts have sorted through all the armored body segments, appendages, crazy spikes, and other fossil features, to reveal a menagerie unlike any that had existed before. Just look at Anomalocaris. This meter-long predator was only a threat to worms on the seafloor, but with 11 pairs of fins, grasping appendages, and a mouth like a camera aperture, it looked menacing enough to star in its own horror movie franchise. Then there’s Hallucigenia, cousin of today’s velvet worms. When it was first described in 1977, experts thought it tip-toed around the seafloor on long spikes. Only later did it turn out that they were looking at it upside down! There were also creatures like Ottoia, a segmented worm with an extendable mouth for slurping up small prey. And the elegant, lacy arthropod Marrella. And then there’s Herpetogaster, which …I'm not going to describe using my words We even had our own little cousin twitching around in those days -- a little, worm-like swimmer that scientists know as Pikaia. Simple as it was, this was one of the earliest chordates -- part of the family that would give rise to the vertebrates and includes us, making us cousins over 500 million years removed. The major groups of animals we see around us today -- from sponges to arthropods to chordates -- all showed up in this little window of time in the Cambrian. But then something happened. Or at least, appeared to happen. At the end of the Cambrian, many of these strange creatures just … vanished. The period right after the Cambrian is the Ordovician, and this is when paleontologists saw a major change in the composition of animal life. Many of the weird animals found in the Burgess Shale - like Anomalocaris - were suddenly gone. Exactly what caused this apparent extinction, no one knew. Looking at the rocks simply turned up very different communities of animals from one time period to the next. This is how extinction events turn up in the fossil record - sharp breaks in the continuity of life. But then, a chance discovery changed everything, effectively erasing what experts thought was the Cambrian Extinction. While looking for fossils in Morocco’s Draa Valley back in the 1990s, local fossil hunter Ben Moula stumbled across a cache of strange invertebrates. He showed the spot to a PhD student working in the area who recognized the ancient life in the rocks. What they found were perfect examples of Lazarus taxa. The fossils they found were about 488 million years old -- which put them in the Ordovician. But some of the creatures looked all wrong for their age. Many of them more closely resembled animals from the Burgess Shale, which lived 20 million years earlier. Some of the fossils were the spitting image of Marrella. And one of the most impressive finds was a two-meter-long cousin of Anomalocaris with its same, frond-like appendages. It turned out, Cambrian creatures that scientists thought were extinct had survived for longer than anyone ever knew -- for tens of millions of years! And this this is by no means the only time that Lazarus taxa have been discovered. The big, primitive-looking fish known as the coelacanth was thought to have been extinct for 66 million years, until one was hauled up off the coast of South Africa in the 1930s. Likewise, the redwood tree known as the Metasequoia was known only from fossils, before a botanist found living specimens in China in the 1940s. But, why does this happen? How can a living thing disappear from the fossil record, and then show up later, alive and well? Well, Lazarus taxa can come about for lots of different reasons. Take the coelacanth. It lives in the deep sea, in environments where living things don’t easily fossilize. It takes special conditions for fossilization to happen, and, for whatever reason, the places that coelacanths like just don’t preserve fossils very well. That’s why there was such a long gap in their record. They didn’t live in the right places to leave their bones behind for us to find! Something similar happened with all those Cambrian creatures that paleontologists thought were long gone. Although some had hard exoskeletons, almost all of them were soft-bodied. And they need very, very special circumstances to become fossils. Unless they’re buried really quickly by a lot of sediment, their bodies are likely to decompose and leaving nothing behind. In fact, there were probably way more living things on Earth than we’ve found fossils for Of all the species that have ever lived, only a handful happened to make their homes in places where fossilization was possible. And of that fraction, only a smaller fraction actually did fossilize and were preserved in rock that happened to be close enough to the surface. And of that even tinier fraction, only a relatively small number are in places that scientists have actually been to. So, the story that the fossil record tells us isn’t like a movie, with every frame intact. Instead, the story it tells is choppy and confusing, with lots of weird plot holes, missing scenes, and characters that seem to be written out of the script for no reason. It’s crazier than Twin Peaks. Which I can make that reference again because it's relevant...at the moment But finding those Moroccan fossils was like recovering a lost reel of film. And that’s what led paleontologists to realize that the Cambrian extinction never happened. It turns out that the kinds of animals that thrived in the time of the Burgess Shale hadn’t died out. They just didn’t fossilize well. And this created a false gap in the fossil record, while they still swarmed the seas. Of course, those Cambrian animals did go extinct eventually. But what makes them special is that they managed to persist for longer than paleontologists ever expected. And this highlights a fundamental truth about the past. The fossil record is huge, spanning more time than we -- who live on the order of decades -- can fully understand. And we’ve only started to explore all of the places on Earth where fossils might be found, and learn what they can tell us. If what we’ve learned so far is any indication, the past is still full of surprises! So if the story of life on Earth really were like a Hollywood film, Lazarus taxa would be less like b-movie zombies that come back from the dead, and more like action heroes, who manage to survive when everyone has given up on them. But instead of cheating death, these guys managed to cheat extinction. Don’t you need a place to post all your Jurassic Park fan art? Of course you do! Whether you need a domain, a website or online store, Squarespace can help you make your next move. And Squarespace provides an all-in-one platform – with templates that allow you to easily set up a website. There’s nothing to install, patch or upgrade, ever. And since you’re an Eons viewer, you can start your free trial at squarespace.com/eons and enter offer code “EONS” to get 10% off your first purchase. So what do you want to know about the story of life on Earth? Let us know in the comments. And don’t forget to go to youtube.com/eons and subscribe! Now do yourself a favor and check out some of our sister channels from PBS Digital Studios. Your brain will thank you!
Info
Channel: PBS Eons
Views: 1,920,177
Rating: 4.8924546 out of 5
Keywords: dinosaurs, dinos, paleo, paleontology, scishow, eons, pbs, pbs digital studios, hank green, john green, complexly, fossils, natural history, Lazarus taxa, Cambrian extinction, Cambrian Period, Burgess Shale, Charles Walcott, Anomalocaris, Hallucigenia, Ottoia, Marrella, Herpetogaster, Pikaia, Ordovician Period, Coelacanth, Metasequoia, chordates, Draa Valley, British Columbia, The Cambrian Extinction, Twin Peaks, Ben Moula
Id: LhyQ5z5f-m8
Channel Id: undefined
Length: 8min 30sec (510 seconds)
Published: Mon Aug 28 2017
Reddit Comments

I'm a simple hairless chimp, I see eons I upvote.

👍︎︎ 32 👤︎︎ u/Nikillo16 📅︎︎ Dec 10 2018 🗫︎ replies

The server doesn't preserve every corpse every time someone gets nerfed. Can you imagine how many there'd be if it did??

Fossilisation is like an Easter Egg for players who (usually accidentally) manage to not get found and mined for XP by the scavenger guilds and bacteria when they die. It's relatively useless for actual gameplay for almost everyone though.

The only builds who seem to care about it are the human players who specialised in the palaeontology skillset, which is an extremely niche knowledge (arcana) skillset playable only for the human build. It's interesting for learning about the history of the game but that's about all you can do with it - I mean there's not much need in-game to know a lot of detail about builds that got nerfed in earlier patches, other than just general interest. Those players seem to be among the rare few who care more about the lore than the actual gameplay, since it takes so much grinding to spec in to that skillset anyway even though the game doesn't reward you much for it. Their playthroughs are how TierZoo gathers a lot of its info about earlier patches though, so us casuals should definitely be grateful.

👍︎︎ 13 👤︎︎ u/BeefPieSoup 📅︎︎ Dec 10 2018 🗫︎ replies

This means that some dinos could possibly still be playable

👍︎︎ 1 👤︎︎ u/Xavier_Woods 📅︎︎ Dec 16 2018 🗫︎ replies
Related Videos
Note
Please note that this website is currently a work in progress! Lots of interesting data and statistics to come.