allow me to educate you about your early roots
Everything started with the archaen era!!!! look! the origin of life! 3500 million years ago!!!! that's like, crazy!! I always feel like I don't have enough time. imagine if i lived a lifetime that lasted 3500 million years ago! i'd be able to get SO MUCH DONE! all my homework, all my studying, all my crafts... I'd always be on time for christmas presents too.. ^^
....anyway, life as we know it now did not exist then yet life was very primitive and simple (unicellular) back then. no TV, no ipod, no boys.. what a life. I drew a pretty accurate representation of the first life form, don't you think? it was so small, you'd need a microscope that magnifies 99935452431345234234x in order to see the thing i drew.
a very important organism was a little tiny thing called Cyanobacteria. yes, it's a type of bacteria and it's green because it's got chlorophyll. chlorophyll? YES CHLOROPHYLL!! it photosynthesizes!! thanks to this baby, when cyanobacteria came into existence, the oxygen levels in the atmosphere for increasing at an incredible rate! this cyanobacteria thing, independent cells that form live in loose aggregations of individuals (aka colony), utilized just a few things here and there, a little CO2, N2, H20, and few mineral nutrients to perform oxygen photosynthesis!! this little thing made life on earth POSSIBLE. let's hear it for cyanobacteria. yayyy-!
next
you'll see it was the proterzoic era!! whoooo hoo! we have another champion joining the ranks of life. it was the first eukaryote! the first unicellular organism with a membrane bound nucleus. now the DNA was kept all nice and organized! and hurray for multicellularity. I suppose, with some support from my colleagues at the lab, that the unicellular organisms started living together in colonies, and started specializing in functions (symbiotic relationship) to become a multicellular organism! the more they come together as one being, the more specialized they become, the more complex the organism became! yayy notice, we still can't see the lifeform. lol...
and finally, after a billion years or so, here came the paleozoic era! from now on, my expert analyses will be below the academic diagram.
as you can see according to this diagram, in the paleozoic era there were five periods. in the first period, something called the Cambrian Eplosion occured, leading to the diversification of INVERTEBRAE!!! look at that! all that variety! different shapes, different sizes. yes. the lovely cambrian explosion. the next period was the ordovician period. it took a couple million (billion?) years, but finally the first fish came into existence. they must have been the evolved forms of the invertebrae that we encountered earlier in the cambrian explosion, yeah?? how interesting! then came the silurian devonian period, when the first terrestrial landforms came into existence! these included plants and vertebrates.
let's me mention the terrestrial plants! how did plants come to live on land? good question. well, it turns out that the ancestors of the first plants were the aforementioned cyanobacteria! they're blue-green algae. but anyway, so cyanobacteria can only survive in completely wet environments (they live in water). but they're not the closest ancestors to green plants! it was th red algae, ulvophytes, coleochaetes, and stoneworts (aka charales). the first three are green algae. coleochaetes and stonesworts luckily came to have sporopollenin - encased spores for their little zygotes. the closest relative to land green plants are stoneworts. those landplants then adapted with cuticles and pores!
what are cuticles you ask? cuticles are a waxy coating on green plants in order to keep the moisture within green plants. but the problem with cuticles is that it's so watertight, airtight, that even precious carbon dioxide could not penetrate the plant! thus, pores for allowing air in made it possible to live on land!
the green plants that initially came onto terrestrial environments were the liverworts! hurray! but you know what, it didn't have stomata! the next two seedless nonvascular plants, hornworts and bryophyta (mosses) now had stomata!!! stomata are like, pores in the leaves that, with the help of guard cells, allow for carbon dioxide to diffuse into the interior of the leaves and stems, and allow the waste product oxygen to be released as well! wow!! amazing!!!!
the plants are miiiiiiiighty interesting, but gotta continue with the epik high paced exciting story of the history of life right??
here's the mesozoic era! I can easily remember mesozoic because there are ... roughly Five periods, right? it started with the archaean, then the proterzoic. those are the two eras that had very minimal life form activity. because next came the three eras that started booming with life over a period of billions of years. the permian era began with the cambrian period! but anyway, since there are only three (permian, mesozoic, and cenozoic) mesozoic is easily remembered as the middle one because it starts with the same letter as middle. hah.. haa... NICE!
in the triassic period, we meet our first mammal. I have no idea what he/she/it looked like. probably rat-ly. the it was the jurassic period! yuuuuuup you know it! we've got our first dinosaurs! btw, did you know that birds are thought to be descendents to dinosaurs? i knoww crazy right! you'd think that they'd be mammally, because they've got a four chambered heart like we do, and it's nice and warm and not scaly at all! it wasn't easy for scientists to accept this until they found evidence in the form of transitional fossils (also known as missing link). it turns out that some dinosaurs ALSO had feathers!!! omfgg wtff right??
then in the cretaceous period, there came to be flowering plants!!!!! "WHAAAT" you're probably thinking. "HOW DID PLANTS EVOLVED FROM THE PRIMITIVE SEEDLESS NONVASCULAR PLANTS INTO ANGIOSPERMS (flowering plants)?" sorry i didn't fill you in. but after the hornworts and mosses, the green terrestrial plant came to have vascular tissue (water conducting tissue). now they can grow higher!! forget gravity! all of the plant needn't be exposed to be water now, due to the vascular tissue! wahoo!
some might helpful stuff called lignin, a molecule built with 6-carbon rings, thickened the walls of the cells! thanks to lignin and the vascular tissue, the early plants could support erect stems and transport water from roots to aboveground tissues! hurray! but it doesn't stop there! vascular tissue became even more complex with tracheids, long thing tapering cells, they've got secondary cell walls and a cellulose based primary cell wall. nice!!! gaps in those walls also increased water transportation efficiency. the most advanced vascular tissue improvement was called vessel elements. even more amazing than the prior ones! and even more so, the extremely strong support material called wood made it possible for plants to stand up straight up tall and proud! all right! way to go for early plants!
lastly, the cenozoic era came, and here in the paleocene period we see mammal radiation! look at all the mammals that diversified and started becoming separate species-s. (plural form of species?) AND FINALLY!! the answer to which you've been oh so eagerly reading this exciting ..memoir for, finally, homosapiens FINALLY came into existence in the neocene period!!!!! HURRAYYYYYYYYYYY!!!! yayy!!
and that concludes this lesson in biology. thanks for reading.
it has been.. evelina. B]