The Cambrian Period: Life's Prototype Stage | Random Thursday

this video is supported by brilliant earlier this week we took a journey deep into the past to ponder the question could there have been some kind of advanced civilization on this planet before humans were around the verdict but today i want to go deeper a lot deeper instead of looking back in time when our ancestors may have been developing the brains to create a civilization let's go back further to when animals were first developing everything and just for a sense of perspective let's pull back our handy little timeline here so from the beginning of life on this earth the planet has been through a couple of different eras the precambrian and the phanerozoic which is the era that we're in right now life as we understand it actually began pretty quickly after the earth was formed in about 500 million years life figured out how to create rna and then dna and enclose that in a sphere of lipids in a way that it could self replicate and single-celled life was born and it stayed that way until here it took two and a half billion years for unicellular life to become multicellular the majority of life on this planet throughout time has been ocean and single-celled organisms along the way life figured out how to photosynthesize light it learned how to create organelles in a nucleus and became eukaryotes and eventually one cell kind of went into another one and decided from that point forward which is going to make energy for the rest of the cell it became mitochondria now cells could power themselves by consuming fuel as opposed to photosynthesis and a whole host of new opportunities emerged and then finally life figured out how to make multiple cells work together as a whole and multicellular life emerged and from here it would take another billion years for life to figure out how to specialize and differentiate those cells creating plants and animals now all of this four billion years of history ninety percent of the existence of this planet is called the pre-cambrian era now pre-cambrian as in before the cambrian era which the cambrian era itself only lasted about 50 million years which is a tiny fraction of the pre-cambrian era now why is the era that makes up the vast majority of the earth's history named after the much shorter period that followed it well that's because the cambrian period is when life just kind of went off the rails [Music] the cambrian period is named after whales in the united kingdom because the roman name or the latin name for whales was cambria and this was where some of the first fossils of this era were found so that's something you know now the cambrian period is set at the beginning of the phanerozoic eon in the paleozoic era and it was such a massive explosion of new life forms that it's often referred to as the cambrian explosion and unfortunately there is not a welsh wrestler named the cambrian explosion but god i want there to be this explosion began somewhere around 542 million years ago and it's believed to have lasted between 20 and 53 million years geologically speaking not really that long now before the cambrian explosion they had what they called the ediacaran period and there were soft-bodied animals around back then but those soft bodies didn't really leave a lot of evidence behind but in the cambrian period we started to see an explosion of mollusks and hard-shelled creatures that did start to leave a record behind but what exactly triggered this sudden explosion of new and bizarre creatures the short answer is we don't know for sure but one theory is that oxygen levels rose to the point that it could sustain oxygen you know based life and this oxygen increase may have enabled a predator class that then had to change their behavior in the morphology in order to catch prey enough so that they could survive and this triggered a rapid evolutionary expanse and of course on the flip side of that is prey species that had to develop defensive maneuvers and defensive body styles in order to keep from getting eaten and here's the thing that is the story of evolution throughout the history of life on this planet it's happening right now but where right now it's sort of iterative changes on bodies and taxonomies that have been proven over time in the cambrian period they were starting from scratch so life just kind of tried stuff the cambrian explosion was basically just life throwing spaghetti at a wall and seeing what's stuck and this process resulted in some of the most bizarre creatures this world has ever seen now just real quick i know there are some undertones to anthropomorphizing life as if it's some kind of conscious being that's making decisions along the way and when it's really just an evolutionary process that made it all happen although the fact that they kind of look the same is interesting plus i'm lazy so i'm just going to keep doing it but regardless of how it came about this was the most significant event in nurse evolution or as guy narbonne said in the journal nature this is the most significant event in earth's evolution so he agrees with me the advent of pervasive carnivory made possible by oxygenation is likely to have been a major trigger of course not everybody is a fan of this theory there's been a lot of debate among scientists and many of them consider some other aspects that might have also been a trigger including increases in oceanic calcium concentrations an expanding continental shelf that allowed for shallow lagoons in which different animals could live and coexist changing ecological relationships between species in terms of food and space creating a rise in predators and genetics such as the evolution of hox control genes that regulate the expression of other genes in the development of animal's life cycle it could have been any or all of these things working together to bring about this drastic change in diversity emphasis on the word diversity because in case i haven't mentioned it already and i know i have twice already the animals that came out in the cambrian explosion were out there though they do generally fall into the similar categories that we have today like chordates brachiopods and arthropods they aren't like anything you would see today except for maybe australia because you know australia one of these animals was so weird it was actually named hallucigenia because it looked more like a hallucination than a real animal it basically looked like a worm with some spikes sticking out of one side and these weird flexible curved things on the other side it was so weird looking that the scientist didn't even know which side was up and which end was front and back it was discovered by charles doolittle walcott in the burgess shale in british columbia in a layer that indicated it appeared somewhere in the middle cambrian period and it's been perplexing scientists ever since for a while they thought that they actually walked on these spines within more examination and more fossils that were found showed that that was actually on their back and those curved things were actually their legs and they even had tiny little claws at the end of their legs and at first they thought that the blob on one end of the animal was a big bulbous head but then they later determined that that was just its inside spilled out when it died yuck so that was the back side and the head was on the other end and they even found a pair of tiny eyes so the best recreation has them looking something like this and while we don't know much about their life cycle reproductive habits and whatnot we do think they fed on sponges because they were found near colonies of sponges so maybe they hung onto the sponges with the claws and they used the spikes for defense or maybe they just wanted to look tough to all the other worms in school either way it was unlike anything that you would see in the oceans today although they think they may be ancestors to velvet worms then there's the five eyed opabenia regalis which got its name from the fact that it has you guessed it five eyes his friends called him cinco this was a small two and a half inch creature that can be described as a lobopod because its body is divided into segments called lobes and it's thought that these lobes both propelled it through the water but also housed its gills one of its defining features apart from it having five eyes was a long proboscis at the front almost like an elephant's trunk they thought at first that it had a mouth at the end of this particular trunk but it turned out that its mouth is actually underneath its body and facing backwards for some reason yeah it would use this proboscis to reach out and grab food and then feed it to its weird reverse mouth it was discovered in 1912 but it wasn't until the 90s that they finally decided that it was an arthropod and you know it's life cycle how it lived how it reproduced all that they don't really know there are only 42 specimens found so it's still a bit of a mystery you know what's also a bit of a mystery starfish most animals have what you call bilateral symmetry meaning if you split somebody right down the middle it would be the same on both sides but starfish have radial symmetry with arms that radiate out from a central point and one of the first animals ever found that had that feature was something called helicocystus this creature lived in the gondwana supercontinent and was found in modern-day morocco it was between five millimeters and 20 millimeters in length and it was shaped similar to an upside down teardrop its body consisted of three parts a cup a stem and a spiral plated section where the mouth is located and that spiral is what makes it kind of weird because it gave it the ability to extend upwards maybe to catch prey now what's interesting about this one is that it actually displays traits from two different kinds of modern echinoderms the palmetto zones and the luther zoans i think i said that right anyway this might be an ancestor between those two or it might just be a bubbly spirally bitey sticky thing another cambrian creature that showed an interesting adaptation was tamascolaris not to be confused with peter scalari from bosom buddies but the scolaris was a member of a group of cambrian animals called anomalocarids which is a pretty well known animal at this point they were the apex predator at the time and looked kind of like a combination of a shrimp and a praying mantis it had two huge frontal appendages that were lined with spikes where it could catch the prey and it just ruled the seas these dudes were vicious and they were big for the time 70 millimeters in length that's more than two and a half feet tamascolaris was the kinder gentler version of menomolecaris because instead of having deadly impaling spikes on his front arms it had soft bristles that it used to more passively capture shrimp-like organisms and krill if anomalocaris was the shark of the cambrian ocean tamaskolaris was the baleen whale in the same way that whales used baleen in their mouths to filter feed a whole lot of krill as they swim through it's thought the tamaskolaris kind of did the same thing with the the baleen on their arms they would just kind of like whiff through the ocean like this and then guide that krill into their mouth this was discovered only recently in 2014 in greenland and it's thought that this is actually a natural evolution that tends to happen from an apex predator when a new source of food a new plentiful source of food is discovered so it's thought that maybe before this happened there was a giant explosion in crow population and the last one we'll talk about here is morello which might be one of the weirdest looking ones but it's also one of the most plentiful with over 25 000 different specimens of fossils found in the burgess shale alone this creature had paired antennae spikes that face backwards on its head and around 25 body segments that each had its own pair of legs it was approximately 2.5 centimeters so about an inch in length and vaguely resembled a trilobite though it was probably not closely related to them and it was thought that they ate organic debris on the ocean floor oh and hey this is fun its stomach was in its head like you do it had two pair of antennae one short and one pair long and sweeping but it also had a triangular dorsal heart with arteries branching from it these weird animals ruled the world for close to 50 million years but all great things must come to an end and the cambrian period ended with a mass extinction researchers think that glaciers and maybe a colder climate may have led to the end of the cambrian critters because the next period the ordovician period showed sediments in the layers that are related to glaciers in locking up ocean water into glaciers its thought would actually reduce the oxygen level in the water basically reversing the thing that made the cambrian period happen in the first place but the genie was out of the bottle life had become complex and by the end of the cambrian period all the different phylums of animals that we have today had already been established and as the world changed the creatures that could adapt survived and they took the best parts of them along with it and those creatures evolved into new creatures that evolved into new creatures that evolved into new creatures that eventually evolved into us by the way if you're wondering exactly how paleontologists know what they know about these creatures they have a whole grab bag of scientific tools at their disposal to figure out where they lived geologically in time and in place how they ate how they reproduced all that kind of stuff et cetera et cetera and that's handy no matter what you do in your life so if you would like to expand your scientific tool kit i can highly recommend the science essentials course on brilliant in this course you'll learn concepts around states of matter kinetic motion heat transfer potential energy and the scientific method through 36 interactive quizzes that focus on problem solving so you can learn it in a way that makes the most sense to you if you want to flex your brain muscles further you can move on to classical physics courses the quantum mechanics courses applied science computer algorithms even competitive math seriously i think if you did every single course on brilliant you would become a super villain so use brilliant wisely plus you can do it on your own mobile device and even offline so you can take it with you wherever you go just please wear a mask by the way you don't have to be that ambitious about it they do have something called daily challenges where you can just go every day to solve a little puzzle it's a little 10 minute thing but over time that brain workout adds up and if you want a taste of what i'm talking about they have free brain teasers and puzzles that you can see if you go to brilliant.org slice answers with joe and the first 200 people that sign up for the premium subscription that gives you access to all their courses you can get 20 off so you've been thinking about trying it out again just go to brilliant.org live sandwiches with joe link is down in the description big thanks to brilliant for supporting this video and a huge shout out to the answer files that are supporting this channel couldn't do it without you t-shirts available at the store answers at joe.com store helps support the channel and there's some awesome stuff there so go check that out please do like and share this video if you liked it and if this is your first time here google thinks this one is something you might like and there's these other that they're down there that have my face on you can go check those out and if you do like them i invite you to subscribe i come back with videos every monday all right that's it for now you guys go out there have an eye opening week stay safe and i'll see you next monday love you guys take care

Channel: Joe Scott

Views: 460,857

Rating: 4.9384799 out of 5

Keywords: answers with joe, joe scott, cambrian explosion, precambrian era, cambrian period, earliest animals, evolution, hallucigenia, burgess shale

Id: inqxEC51jDc

Length: 13min 11sec (791 seconds)

Published: Thu Jul 23 2020