تاريخ الكوكب الحلقة الرابعة الدهر الفانيروزويك الجزء الاول phanerozoic Eon Paleozoic era

we have reached the last EOn yes its only 500 million years which is relatively short but so much events happened in this eon this is why its impossible to say the whole story in one episode this is why we are going to divide the Eon into three Eras in today's episode we will talk about the first part paleozoic era and the paleozoic era is also divided into periods lets start with the first period: the Cambrian Episode 4 phanerozoic eon paleozoic era in the first period the supercontinent gondwana was forming earth was warm the oceans were less salty oxygen was rising and this made the ozone layer even thicker so this caused even more protection in conclusion: perfect conditions for life to flourish this lead to theCambrian Explosion dont panic its not real explosion its metaphore referring to the huge diversification of life in very short period of time in this period appeared huge amount of organisms which are mainly invertebrate means they dont have backbone one of the most important groups is the trilobites the organisms kept evolving and became more complex until we reached to the first vertebrate means they have backbone unfortunately wont be able to pronounce the name of this organism im gonna put the name here, so you do it this organism is going to be the ancestor of all the fish to come this organism is the reason fish appeared but these fish at the beginning were jawless pay attention now in this period the algae climbed on land this event is called: terrestrialization keep that in mind we will come back to it later at the end of the cambrian oxygen levels dropped and hydrogen sulfide in air increased new mass extinction occurred why oxygen dropped we still dont know for sure we entered the second period: the ordivician in this period after the extinction, life flourished again in this period mollusks and arthropods ruled the oceans and on land very important event was happening the algae that climbed on land evolved and this lead the appearance of plants at this point we started having plants on the planet but these very first plants was nonvascular means they didnt have tubes for transporting water they prevented them from being tall plants most of these plants were mosses in this period the water levels increased this lead to more diversification in life in the oceans as plants flourished, carbon dioxide decreased this cooled the earth and we entered new ice age and this ice age killed 85% of all organisms that existed then we entered the silurian period in this period the earth warmed the ice melted water levels went up and the fish were happy this caused the fish to flourish more and diversify this lead the rise of fresh water fish in rivers and lakes not only this first jawfish appeared which are the placoderms scientists like to call placoderms as the armored fish think you can tell why in the devonian period first vascular plants appeared means they have tubes to transport water this lead to the appearance of tall plants by this time we started having forests insects flourished after that the first seed plants appeared keep that in your minds at the end of this period we went through new mass extinction like the usual the reason for this extinction is not fully understood but there are theories that say we were hit by meteors other theories say the level of oxygen dropped anyway what happened had happened now listen to me carefully at the end of this period we were able to find the tiktaalik fossil if you dont know the tiktaalik you know nothing tiktaalik fish is one of the key organisms that existed on earth for being able to use their fins to walk on land and this fish is going to be the ancestor of all the organisms that walk on land with four limbs we reached the carboniferous period in this period gondwana continent was colliding with euroamerica continent this lead to the formation of the famous supercontinent pangea the formation of the pangea caused the formation of high mountains and dry areas water levels dropped alot of the marine organisms died but land animals flourished which are mainly the amphibians not only this the dryness and the coldness wiped alot of the forests and these plants who died in this period we are using them now to charge our phone yes the forests that died in the carboniferous period became the oil we are now using at the end of the carboniferous first kind of reptiles appeared now we reached the last period of this era which is the permian in this period pangea was completely formed as you can see in the picture this supercontinent is surrounded by one ocean only it was called panthalassa we didnt have indian nor the atlantic nor the pacific there was only the panthalassa this lead to more dryness in the center of the continent that lead to the formation of desert who would be more happy than the reptiles this was the reason reptiles were able to reproduce more than everyone else with time new group of reptiles appeared this group is going to play key role in the rising of mammals later on not now during this period most plants that needed alot of water started to decrease in numbers the dominant plants at that time were the gymnosperms like pines at the end of this period like the usual mass extinction occurred huge volcanic activities were happening in the area that is now called siberia this event is called the siberian traps these volcanic activities remained for and due to the volcanic dust and smoke 95% of all marine life was wiped and 70% of the land animals this marks the end of the first era which is the paleozoic and keep in mind so far we dont have birds nor fruits nor flowers not even mammals to know when and how you must watch the next episode which will be on the next era, the mesozoic if you have any questions ask me if you liked the video and if you felt the information is important share it with your friends bye