Cambrian Explosion- More like PREcambrian Explosion & Cambrian Skeletonization | GEO GIRL

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Does the term 'Cambrian Explosion' still hold up? Was it really an 'explosion' of life?
We've learned a lot since naming the Cambrian Explosion, such as the fact that animals not only existed but became quite complex before the Cambrian. We now know that Ediacaran Fauna (animals that characterize the Ediacaran period just before the Cambrian boundary) as well as early representatives of major animal groups on modern Earth predate the Cambrian boundary. However, the evolution of the latter may have contributed to the extinction of the Ediacaran Fauna. However, we don't yet know whether it was abiotic climate and environmental changes or biological competition and predation that caused the Ediacaran mass extinction. All we know for sure is that the extinction of these early 'experimental' animals paved the way for the evolution of the modern animal groups.
Ediacaran and Cambrian fauna differ in many ways, but the major differences were the larger size and greater abudance & complexity of shells and skeletons in Cambrian animals. Cambrian fauna was also much more diverse than Ediacaran fauna with many more animal phyla evolving in the Cambrian compared to the lonely soft bodied corals, jellies, and sponges of the Ediacaran. However, some of the major reef building organisms in the Cambrian underwent mysterious extinctions throughout the period, suggesting that the trend of experimental evolution & abrupt extinction of certain animal groups was not over.
So what was the major cause of the Cambrian Explosion (or the increase in diversity, complexity, and skeletonization in the Pre- and Early Cambrian)? Likely, increased oxygen concentrations [O2]. However, other factors, like increased predation and calcium & phosphate flux to the ocean also contributed to increased skeletonization in benthic animals.
References: Geomicrobiology: amzn.to/2WAloTR
Earth System History: amzn.to/3v1Iy0G
(1) doi.org/10.1016/j.tree.2018.0...
(2) doi.org/10.1126/sciadv.aan8983
(3) doi.org/10.1098/rspb.2015.1003
(4) doi.org/10.1038%2Fnature07072
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Non-textbook books I recommend:
Oxygen by D. Canfield: amzn.to/3gffbCL
Brief history of Earth by A. Knoll: amzn.to/3w3hC1I
Life on young planet by A. Knoll: amzn.to/2RBMpny
Some assembly required by N. Shubin: amzn.to/3w1Ezm2
Your inner fish by N. Shubin: amzn.to/3cpw3Wb
Oxygen by N. Lane: amzn.to/3z4FgwZ
Alien Oceans by K. Hand: amzn.to/3clMx1l
Life's Engines: amzn.to/3w1Nhke
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0:00 Was it really an Explosion?
1:45 Since Naming the Cambrian Explosion…
4:06 Ediacaran Fauna
5:39 Major Animal Groups Predate Cambrian
6:26 Mass Extinction of Ediacaran Fauna
7:32 What Caused Ediacaran Extinction?
9:18 Patchy Fossil Record Makes it Difficult…
11:27 Ediacaran vs Cambrian Fauna
15:05 New Cambrian Life
17:26 Huge Cambrian Predators
18:01 Mysterious Cambrian Extinctions
19:36 Major Cause of Cambrian Explosion
20:43 Why Low Diversity for First 4 ~Billion Yrs on Earth?
23:38 Why High Diversity After ~600 Ma?
25:55 What Caused O2 increase ~600 Ma?
27:10 Summary of Ediacaran to Cambrian Events
28:08 Related Videos & References
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9 июн 2024

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Комментарии : 248

@tedetienne7639 2 года назад

When I try to wrap my head around just how long ago these times were, and how delicate these creatures were, I’m amazing we know anything about them at all. It’s a real testament to the hard work of geologists to find these facts out!

@GEOGIRL 2 года назад

So true! It is quite amazing the information we have gained from examining the rock record! ;D

@LuisAldamiz 2 года назад

Homo sapiens time span: less than 7000 generations (30 years each). Overall human time span: ten times that: c. 70,000 generations. To the Cambrian... a thousand times that: 70,000,000 generations (of human standard). I believe it feels a bit less overwhelming to think it that way: "only" a thousand times to the Cambrian as to Homo habilis. I'm pretty sure that it looks like a thousand times all of human evolution is necessary for primates to evolve out of those dubious fragmentary fish-like remains GeoGirl mentioned. You need a lot of evolutionary time to climb to a non-watery landscape and then to trees (which also needed to evolve). It seems it was much easier to go back down to the ground... but the dream of Cousteau of colonizing the depths of the seas remains a no-no for us so far. In any case, 70 million generations doesn't sound that distant to me when you need to account for evolution happening so dramatically (from dubious proto-fish to computer typing ape with mostly correct grammar and spelling, amazing!)

@phadrus Год назад

It’s sheer speculation and guesswork. Nobody was there, so nobody knows.

@theshadedofinnsmouth6243 Год назад

@@phadrus I was.

@jenelyngalindez4192 Год назад

@@phadrus egads...yet another 'you werent there SFB (pooh between ears) Fun how sooooo many crimes are solved, with no witnesses...just based on evidense and what it tells us

@donaldbrizzolara7720 2 года назад

Rachel: Excellent review of this fascinating subject, a subject that has always intrigued me. What I always love about your videos is how in a vey short period you get me current on most every topic. In the 1960s I actually started out as a zoology/ paleontology student at UC Berkeley when the Burgess Shale fauna was pretty much all we knew about this period and it was also at this time that we first received early lectures on a radical new ideology…plate tectonics. Then for me a hiatus…the Vietnam War. Upon my return I pursued a geology degree followed by grad school at UC Davis. It was then in the mid-1970s that we first learned of the Ediacaran fauna and more refined concepts of the Cambrian explosion. So much has been learned since but still only the surface has been scratched. Thanks once more for recharging my old brain with new knowledge. You provide a wonderful service.

@GEOGIRL 2 года назад

Of course, and thank you again for sharing your amazing experiences here! They are all so inspiring :D

@havellsgec4578 Год назад

@@GEOGIRL I love you 💙💙💙💙💙💙💙🍎💔💔💔💔💚💚🧡🧡🧡🧡🧡🧡🧡🍎

@nomdeguerre7265 Год назад

Back in the late 60s and early 70s I found the Ediacaran fauna fascinating because it was so obviously complex, but also so mysterious and poorly understood. I remember during my first visit to the American Museum of Natural History during that period finding one rather small and abbreviated display, at the very beginning of the hall containing the history of life on Earth. Its paucity and ambiguity made it compellingly interesting to me. Over the years it has been interesting to follow the advance of our knowledge and understanding of this distant period, its life and role in the process leading to the diversity of complex life. While the rarity of a complete fossil record may prevent as comprehensive knowledge as some other earlier periods that only makes it more persistently compelling. Science, after all, isn't really about what we know. Science is about what we do not know. Thank you for publishing this excellent overview of recent scholarship on this fascinating area of scientific exploration.

@JoesFirewoodVideos 2 года назад

This is what I needed to watch tonight, thanks for making it. I ❤️ GEO GIRL

@GEOGIRL 2 года назад

So glad to hear that, hope you enjoy it ;)

@charlesjmouse Год назад

Thank you again for another excellent run-through. Among the interacting influences that led to the Cambrian explosion something I find enlightening when it comes to how much of an influence oxygen (or it's lack) has is when considering trophic levels and so the potential for diversity that implies. As I understand it anaerobic metabolism will support something like 2-3 trophic levels while aerobic metabolism will support 4-5. Not a huge difference? Consider: As a rough and ready estimation for the complexity of food webs your trophic levels can support raise the number of 'dimensions' your environment possesses, say 3 for simplicity, by the power of your potential trophic levels... 3 gives 27 and 5 gives 243... so roughly 9 times the potential niches to occupy and all the extra diversity that allows. For just a little oxygenation!

@ArturdeSousaRocha Год назад

I love the deep dive. First time on your channel, I subscribed before the 10 minute mark.

@ketonshaw4809 2 года назад

This video was quite the gem. Thanks for all you do. 🤘🏻

@GEOGIRL Год назад

Thank you so much! This is one of my favorite videos I've ever made, so I am very glad to hear that you think it is good as well :D

@KAZVorpal 11 месяцев назад

Earlier, I made a comment on your "Boring Billion" video saying just what you say here. In my defense, I'm used to being disappointed by "science" channels. You are an exception. Thank you.

@rovanderby759 Год назад

Interesting video. I fear that the term 'Cambrian Explosion' will always remain one of those scientific misnomers we can't get rid of anymore, just like the 'Big Bang' or the 'Fall of Rome'. But it would be a great name for a Welsh show wrestler 😄

@GEOGIRL Год назад

Haha yea, I agree, scientists will try and change terms but it never works once something has stuck ;)

@pacotaco1246 Год назад

I propose: The Cambrian Bonification

@Alberad08 Год назад

Thoroughly researched and well-presented video - thanks a lot for sharing. BTW I never thought of Opabina as an Anomalocarid, but I instantly could see this connection when looking at the presentation board in 17:30.

@jaisonbasumatary9519 2 года назад

I'm currently doing my Masters in Geology since I did not have anything in my mind after my Bachelors. When I started Masters thinking to quit came in my head but while in RU-vid I happened to encounter this channel and it has totally changed my mind. I am gaining interest in the subject and this credit goes to you Ma'am. Thank you. I thank you for keeping such videos which are really helpful for me as I am starting from scratch again. Love you and this Channel.

@GEOGIRL 2 года назад

Oh my gosh, thank you so much for this comment, Jaison! This made my day :D I am so happy that you didn't quit and I am so honored to have helped you regain interest! Best of luck with your Masters, I have no doubt you will be a great geologist! ;)

@jaisonbasumatary9519 2 года назад

@@GEOGIRL Thank you Ma'am 😊

@justinjackson2588 Год назад

Why are your videos better than the documentaries I see on major channels? Keep it up lady. I am binging your videos.

@GEOGIRL Год назад

Thank you so much! Hope you enjoy the other videos ;D

@briseboy Год назад

Australians pronounce the place: EE-Dee- AAck[a]ra. Geogirl, your videos constitute an outstanding curriculum, seminar series, book for students of ALL ages from primary right through postgrad overviews, and reviewing! Thank you! Those who have never touched live sponges, by the way, they are considerably stiffer than the boiled remnant with which those who have not dived, understand sponges to be. Greater understanding of evolutionary process can be had in the evolutionary development literature, with its easy explanations of repetitive expression of HOX genes and the ways in which very specific epigenetic shutting off occurs. Body shapes of Precambrian and Cambrian organisms show most clearly the simple repetition that , elaborated, contribute to the enormous diversity Chuck Darwin commented on, that we see everywhere, even though we ourselves live during a period of biotically-driven mass extinction.

@barbaradurfee645 Год назад

Thanks for insights

@EvilSnips Год назад

This is my favorite time period! Thank you for being a woman covering science topics, it is very rare to find. I am a young woman as well interested in studying biology and paleontology to it is nice to know there are others out there!

@oker59 2 года назад

Going from single cell to multicellular life was almost as great an accomplishment for life as going from the sea to land! That's kind of what I'm taking from this - thanks and good job as usual Geo Girl!

@oker59 2 года назад

The question I've always had about the Cambrian is how many different body plans were there? I found it very hard to get a number on this. I think I saw one count was forty. Today, I think it's four or five. Stephen Jay Gould makes is sound like there was thousands!

@GEOGIRL 2 года назад

@@oker59 Thanks for the comment, so glad you enjoyed the video ;D Also, what an interesting question! I think this would be a hard question to answer because how do you define 'body plan'? Maybe reword it to say 'species' and you might find more estimates... although getting a species number for so long ago would also be difficult and mostly based on mathimatical model estimations.

@oker59 2 года назад

@@GEOGIRL I'm thinking phylum is the more scientific name. But, even that definition looks to be made more rigorous; or, at least some think even phylum isn't rigorous enough. They're still working on that!

@GEOGIRL 2 года назад

@@oker59 Oh well determining the number of phyla from the Cambrian would be much easier than determining number of species! But the problem is that phylum is such a large taxonomic group that the phyla list from the Cambrian would not be that different than the list of modern phyla. For example, modern phyla, like porifera (sponges) mollusks, cnidaria (corals & jellies), annelids, echinoderms, arthropods, etc. were all already present by the Cambrian period. So if your interested in 'body plans' I would suggest using a term more specific than phylum, especially because many body plans can be found in one phyla (example: humans belong to the chordata phylum which also includes things like fish and birds, which definitely have different body plans haha). The good news is the number of body plans in the Cambrian would be much less since large multicellular organisms hadn't been diversifying for that long and there weren't any terrestrial forms yet. Anyway, sorry to ramble on, but it is a intriguing question you pose! I love the curiosity! Hopefully someday we will have more definitive answers ;D

@oker59 2 года назад

@@GEOGIRL Sounds like the Cambrian explosion puzzle is being solved by showing the question "wasn't properly posed!"

@toughenupfluffy7294 6 месяцев назад

Rachel, your content is top-notch, well presented, scientifically accurate, and very entertaining! Congratulations for such a high quality channel!

@darth856 Год назад

Very nice presentation. You held my interest the whole way through, which is an accomplishment in itself since I'm easily distracted (internet has ruined me lol). Well done.

@GEOGIRL Год назад

Thank you! So glad to hear that ;D

@ripdoggie Год назад

Finally! Been waiting for this video… the ediacaran fauna is soooo interesting.

@krinklesofmadness Год назад

YESSS first channel I’ve seen bring up dickinsonia and other Precambrian fellas. Thank you for spreading the word of our Proterozoic ancestors

@AlEndo01 2 дня назад

You're a smart and very gifted communicator. Congrats on your doctorate!

@TheGloriousLobsterEmperor 7 месяцев назад

This was insanely fascinating, thank you! Ediacaran life is unfortunately so under reported on!

@ellenmcgowen 2 года назад

A great presentation on one of the most interesting topics in paleontology (I think), with a lot more substance than I've encountered previously. Unfortunately two of the papers are behind paywalls :-( but I look forward to reading the other two. Thank you!

@GEOGIRL 2 года назад

Thank you for the comment! And oh no, I wish they weren't unaccesible for you. Well, I hope you enjoy the other two and I also hope that someday everything will be open access, but that may be a bit in the future unfortunately. :/

@unstoppableExodia Год назад

Wild Geo Gurl appeared in my recommended feed. Wild Geo Gurl wants to educate, she used paleo-biology. It’s super effective !!

@punditgi 7 месяцев назад

Geo Girl provides us with an explosion of knowledge! ❤🎉😊

@johncarr7212 Год назад

An amazingly well done, and researched video. Keep up the good work.

@wedgewizard5429 Год назад

I would really like to see a good 3D aproximation of what life must have been like back then (most of the ones I've seen so far have been underdeveloped). It must have been a hoot. How did the Hallucigenia move around? Who were the big predators and how did animals hunt and hide from each other? It must be difficult extrapolating that from limited fossil data. Also when you said skeletonization I thought you meant animals eating each other and leaving the bones and not just evolving to have skeletons! Now I feel like a silly person! 😂

@wcdeich4 Год назад

Hi. You requested comments about chordates. Myllokunmingia & Haikouichthys are 2 of the oldest Cambrian fossils that are almost certainly chordates. Pikaia is a slightly younger fossil, but appears even more basal; then again, it is so basal, some people debate if it is even a chordate at all. But interestingly, genetics suggest the closest living relatives to chordates are tunicates, so maybe the ancestors of chordates were tunicates that never settled down, maybe something like Xidazoon stphanus.

@GEOGIRL Год назад

Wow, that's awesome information! Thanks so much for sharing this :D Now I have to go look up what all these funny named organisms looked like haha

@sydhenderson6753 Год назад

Lancelets figure in there, too. I usually see them and tunicates put in Chordata since they have notochords for all (lancelets) or part (tunicates) of their lives, though some biologists want to split them off.

@josephfeldman-peterson1148 10 месяцев назад

Working on an undergrad mini-grant proposal and this video has been super useful for understanding the importance of and what determines the Precambrian-Cambrian boundary! Basically, there are some inconsistently young dates that tantalizingly point to the possibility of moving the boundary younger still from the most recently agreed upon 539Ma...

@takashitamagawa5881 Год назад

Excellent video. The discussion of the Ediacaran fauna bring to mind a decades old essay by evolutionary biologist Stephen J. Gould about this topic. He presented the view that those animals were a branch of complex life that followed a path not taken by modern animals. The vital functions of metabolism such as digestion, respiration, and excretion depend on surface area of the metabolic systems. Because surface area relative to volume decreases as the animal size increases it is necessary to form complex structures in the gut and in the respiratory organs (gills or lungs) to maintain a sufficiently large area to carry out the needed level of function. Ediacaran fauna on the other hand may have gone the path of increasing the functioning area simply by maintaining a flattened form while increasing in size. It may be, Gould suggested in his essay, that an alternate evolutionary pathway was explored by the Ediacaran fauna and it came to an end just before what is now referred to as the Cambrian explosion took hold.

@mikesnyder1788 Год назад

The late Stephen J. Gould first introduced me to these early Cambrian creatures in his astounding monograph "Wonderful Life." I am sure his findings have been reviewed and possibly corrected by later researchers but for me it was a great introduction to the wonders of The Burgess Shale.

@takashitamagawa5881 Год назад

@@mikesnyder1788 Yes, I also read “Wonderful Life” years ago. I think that the late Stephen Jay Gould is very much missed in this century. He wasn’t always right about what he discussed in his essays and books but among other things he was someone who could present the ideas of “deep time” in biology and geology to the general public in an understandable way. I don’t have Gould’s particular essay about the Ediacaran fauna that I previously brought up in front of me but if I remember correctly he was discussing the work of German paleontologist Adolf Seilacher, also now deceased. His theory of the dead-ended evolutionary pathway of that fauna is intriguing, if controversial.

@mikesnyder1788 Год назад

@@takashitamagawa5881 Yes, he is very much missed! I enjoyed reading his essays even if he loved bringing up non-related topics to prove a point that he wanted to make. I even had an opportunity to see him give a live presentation in the mid-1990's. I was unaware of his essay about the Ediacaran fauna and I just became aware of this era a few years back. All good stuff. Regards!

@kylemacleod4653 2 года назад

Love your videos! Would've loved to hear a mention of the Mistaken Point Ediacaran Fossils in Newfoundland Canada

@GEOGIRL 2 года назад

Thanks so much, so glad you enjoy my videos! Thanks also for the suggestion, I will look into that ;D

@numericalcode 4 месяца назад

Great job on the references! Very useful!

@praveenl9655 2 года назад

Thank u for taking up this topic. Had lots of doubts. Its cleared now✌️

@GEOGIRL 2 года назад

Thank you! So glad I was able to clear things up about this topic for you ;D

@Hellbender8574 2 года назад

Hi, I really appreciate your videos, especially the ones about fossils. My son and I found a shale bed near our home chock full of fossils and your vids have tons of easily accessible info to learn about them.

@GEOGIRL 2 года назад

Oh my gosh, how exciting! A shale bed should have some great finds since that type of environment likely preserved organisms in a more gentle way than many other environments, meaning that you may be able to find some delicate parts of organisms like leaves for example! I'd be curious to hear what kinds of organims you've found! ;D Also, thank you for the comment and support, I am so glad my videos have been helpful for you and your son ;)

@Hellbender8574 2 года назад

@@GEOGIRL The gray shale is in the Appalachian mountain region. So far, we found sea life: big clumps of brachiopods, horn coral (rugosa), branched-shaped bryozoans, little snails, larger mussel-shaped shells (maybe a bivalve). And one I haven't identified yet that looks like thin bunches of roots or stems covered in a thin layer of shiny graphite-colored material (could it be another bryozoan, soft coral sea whip thing, seaweed, maybe a trace fossil?). Plus a crinoid stem in a nearby gravel bed by a stream. The more we look the more we find. You can just picture the busy ancient reef ecosystem. Again, thank you for the informative videos, and thanks for the response!

@GEOGIRL 2 года назад

@@Hellbender8574 Wow, what great finds! yes, the reef system must have been marvelous there! Thanks for sharing and happy hunting ;D

@Smilo-the-Sabertooth 2 года назад

Well you know what they say, Life will find a way. We learn something new everyday but sometimes the things we learn need double checking. Just by digging a little deeper, we will gain a better understanding about the things that fascinate us the most and who knows what astounding new discoveries we’ll uncover next. And as a big time Earth enthusiast, I personally know that this big crazy world is nothing short of remarkable. 💚🌎💙🌍💚🌏💙

@GEOGIRL 2 года назад

Couldn't agree MORE! Earth and it's biosphere is quite incredible and has clearly been incredble for millions of years! 🌏🌎🌍😍

@a.randomjack6661 2 года назад

@@GEOGIRL If there was a god or preferably a goddess of randomness, I likely would not be an atheist 😁 Love tour educational videos 🤓

@Smilo-the-Sabertooth 2 года назад

@@GEOGIRL Very true. And there is no better place to learn about this big crazy world than here with you on your amazing channel. Nobody knows that better than me which is why I’m always more than willing to give my full support to you and your channel that I really love. ❤️😊👍

@Smilo-the-Sabertooth 2 года назад

@@GEOGIRL And as usual, it’s always such a tremendous pleasure for me to learn with someone as beautifully gifted and intelligent with a bright and promising future like you my favorite teacher and I look forward to learning more with you as I continue to give you and your amazing channel all of the support you more than deserve my friend. You’re truly amazing Rachel. 😉❤️😊👍

@GEOGIRL 2 года назад

@@Smilo-the-Sabertooth Thank you my friend! As always, you are giving my a bigger head than I deserve hahaha, but I appreciate your support and encouragement so so much! ;) And I am so glad you enjoyed today's video :D

@uncleanunicorn4571 Год назад

20:50 Some call the Neo-proterozoic the 'Boring Billion', but I wonder how many questions about endosymbiosis we could answer to sample the waters back then?

@user-sh4nn2bv6j 7 месяцев назад

Love your videos! Well made! Very informative! Very impressive! I am an earth history buff.

@sezersekmen5826 2 года назад

thank you teacher. Can you upload slides in PDF format?

@GEOGIRL 2 года назад

Thanks! I hope you found it helpful :) I am sorry though, unfortunately due to copyright law I cannot upload the raw pdf or ppt files because I don't think it is 'transformative' enough to be considered 'fair use' since many of the figures and images I use are not my own. But you can always take screenshots if you need ;)

@thhseeking Год назад

Poor Stromatolites :P They're still just hanging on in Shark Bay on the west coast of Australia. I think that they're somewhere else, too. Just. :P

@barbaradurfee645 Год назад

Love this content!

@OLIV3R_YT Год назад

I'd lie if I said I understood everything here, but I find it super interesting and fascinating nevertheless :) Thank you!

@geoscilove6609 2 года назад

Thanks for this video geo girl!

@geoscilove6609 2 года назад

Looks interesting, gonna watch tonight!

@GEOGIRL 2 года назад

@@geoscilove6609 Thanks! I hope you'll enjoy it, it is one of my favorites so far :D

@ediacaran630 Год назад

Excellent

@dustinfindsrocks Год назад

More like the Cambrian skeletal explosion, fascinating! Great video!

@mymom1462 Год назад

Thanks for your videos! I have a dumb question: If we know that what we assumed to be the Cambrian Explosion was more like a Precambrian explosion, why don't the Geologists shift the Cambrian back by ~50-100 Ma or back to whenever we can observe what we initially assumed to have only begun in the Cambrian? I know that I am asking this with not a lot of knowledge in this field but I assume that these boundaries were stratified and labelled based on the observation that on this (Cambrian boundary) specific index is where we see more diversity while before it we see less, right?

@GEOGIRL Год назад

Not a dumb question at all! A very valid question actually! You are correct that we base the boundaries in the timescale off of major events in the rock record. But the Cambrian boundary was initially set because all of the new hard bodied organisms found right above it. Even though we now know that diversity had increased before the Cambrian, this boundary is still the first widespread increase in hard bodies/skeletons, so we still use the same age for the E/C boundary. AKA: Ediacaran now marks the diversification, but the Cambrian still marks the skeletonization. Does that make sense?

@dmbeaster Год назад

The boundary lines for many (but not all) of the geologic ages have always had an arbitrary quality, and were established long ago based on much less information than we have now. There is a tendency to keep the existing boundaries rather than move them around. One non-arbitrary basis for boundaries have been what we now know were major extinction events. And one of the current theories trying to explain the difference between Ediacaran and Cambrian life is that there was an extinction event such that most forms of Ediacaran life did not make into the Cambrian, and the newer forms of Cambrian life proliferated. In other words, still an "explosion," but just not the beginning of multicellular life. Also, predation seems to be a key thing that differentiates the Cambrian from the Ediacaran, and promoted the evolution of hard body parts that made the Cambrian so different. The boundary still makes sense, but the nature of and reason for the boundary is what has been redefined.

@kevinrussell1144 Год назад

@@dmbeaster DB: I would rather say the boundaries (that all geologists have learned to work with) were recognized and defined rather than being "arbitrarily chosen". The rock record is episodic and non-uniform. Classification has "progressed" from simple to very complex. Cambria identified a region (and an extinct tribe of savages who once lived there) in Wales where geologists first described and began to understand the true significance of bedded rocks. We owe much to these early UK scientists. Cambrian rocks (some containing fossils) were differentiated from slightly younger sections that ultimately became the Ordovician and Silurian "series", also named for extinct tribes. The set up and principles of stratigraphy IS an endlessly fascinating topic and has remained a lifelong interest of mine. I see no problem at all with the use of "Cambrian Explosion" . Carbonate rocks appear in the record more than a billion years prior to the Cambrian, and by their existence they prove the presence of life, but the diversity of forms (the four Phylla she mentions as appearing at the boundary are THE major elements of Paleozoic invertebrate life) and the shear volume of trilobite, echinoderm, brachiopod, and coral forms and their eroded debris that suddenly appears in the record is in overwhelming contrast to what came before, even though we can guess their precursors must have existed in the NP. In passing, it's good to note, too, that not ALL geologists buy the snowball earth story for the Neoproterozoic. I look upon the time period between ~800MY and the Cambrian Explosion as an incredibly curious time span, a one-off sequence of events that could be modified and interrupted but not really repeated, because the game fundamentally changed. It is a dance time between oxygen levels, CO2, and tectonics, and abundant complex life was the major gift. I think what we're talking about is the breakup of the older supercontinent "Rodinia". This breakup created highlands and rifts, and the history of this is preserved in NP rocks. The abundance of terrigenous rocks (sandstones and siltstones) in late PC sedimentary sections speak of relief and highlands (and their weathering and erosion), whereas the gradual eclipsing of these rocks (in the upper NP and LCambrian section) with carbonates speaks of broader continental shelves, warmer conditions, and increasing atmospheric O2 and CO2.

@mymom1462 Год назад

@@GEOGIRL It does make more sense now. Thanks for the response!

@nomdeguerre7265 Год назад

@@kevinrussell1144 Careful there. You wouldn't want many a 'Fluellen' to assail you for inadvertent insult to their forebears. "I beseech you now, will you voutsafe me, look you, a few disputations with you..." ;)

@omeryalcnsar2391 2 года назад

Ediacaran faunası sonrası bu popülasyon sırlarla dolu ...neşriyatlarından istifade ediyoruz...çok teşekkürler Rachel..

@duhduhvesta Год назад

Thank you

@christopher3d475 2 года назад

It's my understanding that the Cambrian explosion period was unique in its soft-body preservation relative to later fossil periods. I was watching a documentary about the Burgess Shale and they mentioned that fact.

@GEOGIRL 2 года назад

Yes, you are right, the Burgess Shale is a wonderful rock formation that preserved many Cambiran-aged soft bodied organisms (and soft parts of hard bodied organisms) in a perfect preservation environment, but in general, the defining characteristic of the Cambrian Explosion is the appearance of more skeletonized and shelled organisms (but obviously, there were still plently of soft ones out there to get preserved in the Burgess Shale) ;)

@christopher3d475 2 года назад

@@GEOGIRL Ok, thanks. I have a fascination with this time period and I wonder a lot about creatures like anomalocaris, they seem to just appear in the fossil record. Is it possible their predecessors were creatures with softer body parts? Were they also evolved from much smaller creatures that existed at such sizes because of the lower oxygen content? We know that creatures got big during the Carboniferous period precisely because of the oxygen levels. So many questions.

@GEOGIRL 2 года назад

@@christopher3d475 So many great questions! I would say absolutely to all the 'is it possible' questions haha! To the thrid point about the Carboniferous, the huge animals were due to the oxygen levels in the atmosphere that increased the growing ability of arthropods specifically (such as insects, spiders, crustaceans, milli and centipedes), but other animals would not have been affected because oxygen does not play as vital a role in their growth process. However, in terms of the lower oxygen levels before the Cambrian, that would have inhibited both size and functionality (due to the increase in energy required by larger sizes and more complex functions) because oxygen was required for a more energetically yielding metabolism, but the rise in oxygen in the Cambrian led more so to an increase in diversity and animal complexity than an increase in size. For example, large animals were possible at lower oxygen levels before the Cambrian, but they would have had to be simple like sponges and jellies because those dont require super high energy yields, whereas more complex swimmers, burrowers, predators, etc. could evolve once more oxygen (and thus, energy) was available.

@darkgeologist Год назад

hi geo girl , i m very happy there is a channel in you tube that talks about geology

@GEOGIRL Год назад

Thank you so much! I am glad you like my channel, I hope you find it helpful :D

@TheRazagen Год назад

Shout out to all my Ediacaran fauna who made all this possible.

@criticalbasedtheory 9 месяцев назад

I just made a video on this subject as well! Just wanted to say I’m a huge fan of what you do and can appreciate the time and effort you put into your content!

@GEOGIRL 9 месяцев назад

Thanks so much! You're channel looks awesome too, keep up the good work! ;D

@platzhirsch4275 Год назад

scientists have attributed the eyes of a trilobite to be, "the greatest living lens. The trilobites' eyes were different than most creatures' eyes because they were composed of materials that could be studied even after being fossilized. Most creatures' eyes dissolve after death: tilobites eyes did not. When scientists began studying these eyes, they were amazed at what they found. Humans have only one lens in each eye. But trilobites had two lenses in each of their many eyes. In order to see clearly under water, it was necessary for them to have this "double lens" in each eye. If their eyes did not have two lenses, things would probably have appeared distorted. The scientists discovered that the lenses were so perfect that there would have been no distortion at all. Since trilobites are considered to have been one of the first creatures to evolve, it would make sense (from an evolutionary point of view) to suggest that they possessed fairly primitive features. Yet the eye of the trilobite is anything but primitive! How could this "perfect eye" be found in an "early" animal like trilobite?

@alexjackson9997 Год назад

That was quite a lot to take in....approx 3.5 billion years :)

@fungi8460 Год назад

19:00 "rock record" 💿🎸🤟

@trilobite3120 4 месяца назад

5:59 Also Yilingia if I remember correctly.

@mandobob Год назад

I have never been a fan of the Cambrian Explosion term. I find it a bit too "golly gee wizy" pop culture for my taste. Although I admit it is a bit more catchy than Cambrian radiation or Cambrian diversification and anything that gets the general public interested and enthused about Geology is a good thing. I have always considered the extensive unconformity at the PC - Cambrian boundary (whether enhanced by world-wide glaciation or not) undoubtedly increased ocean nutrient input and that coupled with increased shallow marine environments set the stage for rapid organism radiation.

@slappy8941 Год назад

🎶🎶 _The Cambrian explosion!_ 🎶🎶

@edgeeffect Год назад

I get the feeling that you should be saying "maybe", "perhaps", "probably" far more often when describing the Ediacaran biota.

@kerriemckinstry-jett8625 2 года назад

Thank you for scratching a serious wanting to learn more about Ediacarans itch. 🙂

@GEOGIRL 2 года назад

Of course! So glad you enjoyed it ;D This is probably one of my favorite videos I have ever gotten to make, it is such a fun and interesting topic in my opinion :D

@kerriemckinstry-jett8625 2 года назад

@@GEOGIRL I love geeking out on this stuff. If I hadn't gone into astronomy/astrophysics, I would have probably become a paleontologist or something. 😀 I may be referring some of my students to your videos. They always give me such incredulous looks when I tell them Earth's atmosphere didn't really have much O2 until about 2.5-2 Gya, and not really even a "normal" (by our standards) composition until the Precambrian fauna really got going. They also tend to overlook that O2 isn't enough... you need O3 (which is easier to obtain once you have O2). I have had to explain to my students why you don't want to spend a lot of time on the surface of a planet without any atmospheric protection from the higher energy light from the parent star... It's so cool that life forms initially had to be protected by the ocean & managed to radiate into all of the life forms we see today. 🙂 Thank you!

@GEOGIRL 2 года назад

@@kerriemckinstry-jett8625 Oooh! You are an astronomer?! That is so awesome! Much of my research is geared toward astrobiology, and I am currently doing a NASA internship that is giving me so much appreciation for astronomers & astrophysicists and all that they have to consider in their research! Also, that's so funny about your students giving you funny looks about the lack of oxygen on early Earth, I get those too! I hope they enjoy the videos, and if there's anything that I haven't covered that you or they would like to see, let me know and I'll try to make a future video about it ;) Thanks again for your support! I am so honored by the fact that I have extremely knowlegable people in my audience like you! ;D

@kerriemckinstry-jett8625 2 года назад

@@GEOGIRL Hi! 🙂 Yes, I teach astronomy, physics, & physical science as an adjunct at a couple of colleges in my area. That is so awesome, that you're interning at NASA! I hope that's an amazing experience! My students also look surprised when I tell them how much life alters the atmosphere of a planet. They know that we breathe O2 & produce CO2, but they don't really make the connection that it makes a difference to Earth's atmosphere. I just found your channel today because I'm trying to put together resources for the Pioneer Valley STEM Network. Basically, the network's mission is to support teachers with STEM education & encourage students to go into STEM fields. We also foster partnerships with local companies in the STEM fields & schools. MA has a special STEM week every year, and teachers need resources, inspiration, etc. I haven't watched all of your videos, yet, but plan to. Please keep up the good work! 🙂👍

@GEOGIRL 2 года назад

@@kerriemckinstry-jett8625 Wow! What important work you do! I know in academia it's hard to find the time and effort for outreach but sounds like you are doing that as well, which is so inspiring! I am currently working on my PhD and hope to someday be teach as a professor as well ;D Hopefully someday we can make it common knowledge that life alters the Earth's major atmospheric and oceanic cycles! ;) Thank you so much for your support and for everything you do, it means the world, and I hope you enjoy the rest of my videos!

@nicholasmaude6906 Год назад

It would be interesting with the advances in genetic-engineering if scientist could create Trilobite analogues by genetically modifying Horseshoe crabs.

@wcdeich4 Год назад

BTW @Jackson Wheat said Charnia is not actually a Sea Pen, but Cloudina turned out to be an annelid word, maybe even related to Polychaetes.

@GEOGIRL Год назад

Wow so cool! Thanks for sharing that ;D

@erlgunslinger7344 Год назад

Is it possible spriggina is an ancestor to trilobites? I’ve always been struck by the morphological similarity.

@GEOGIRL Год назад

I have always wondered the same thing since they look so similar! But from what I've read it seems it's difficult to say because they are separated by a bit of time and the only leg to stand on is morphological similarities and those can always be due to convergent evolution. So it depends on whether the separation between them in the fossil record is due to different evolutionary timing or incomplete fossil record. So only time and more paleontologists will tell ;)

@ChemEDan Год назад

@@GEOGIRL Triops! There are some that live in pools at "The Wave" outside of Kanab UT. Probably the closest thing on Earth to experiencing another planet; I'll never forget it.

@dmbeaster Год назад

One big difference is the lack of leg structures, which is a defining characteristic of trilobites. But that could also just be a consequence of their preservation as body molds in sandstone

@kaileaugust4980 2 года назад

I really enjoyed that

@GEOGIRL 2 года назад

Thanks! I am so glad to hear that ;D

@omeryalcnsar2391 2 года назад

Tebrikler Rachel....♥️

@sent4dc Год назад

I'm wondering why didn't the first oxygenation event (the one that happened almost a billion years prior to the Cambrian explosion) did not cause such a diversification of life? It seemed like it generated way more oxygen back then.

@GEOGIRL Год назад

Actually my most recent video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-nhKYFjNpDLM.html is one that discusses this exact point! Well it's about whether oxygen triggered animal evolution, so I talk about the GOE and NOE in that video and how the GOE raised oxygen to near-modern levels, but then it quickly rebounded to only about 1-10% modern levels and remained very low for the next billion or so years until the NOE, which finally allowed oxygen levels to not only rise but also stabilize at higher levels and that likely allowed animals to evolve. However, I should mention that eukaryotis evolution occured almost directly after the GOE, so at least unicellular eukaryote evolution might have been 'triggered' by the GOE, whereas multicellular complex eukaryotes like animals required the NOE. Hope that makes sense ;)

@sent4dc Год назад

@@GEOGIRL hmm, yes and no. It makes sense what you said. It is probably the graph in your slide that had a horizontal line for the Oxygen from the GOE to the NOE event that made me ask that question. But now I'm wondering what made the O2 drop so precipitously after the GOE event - was it also in that other video? I'm asking like we know everything. ;) Thanks for doing these videos btw. I was always fascinated by the subject of deep time, and also always dreamed about how cool it would be to witness at least one of those global events in the Sagan's "ship of imagination." probably collision with the protoplanet that formed the moon would be my pick.

@girishkumarverma5863 2 года назад

You make geology beautiful like you❤

@royaleblizzard2460 2 года назад

This part.....Love it 😜

@ohgodthatdude1395 Месяц назад

Is there any links to an increase in Barite & Pyrite?

@bornnaked2928 Год назад

Ctenophora is pronounced "Teeno-fora". The c is silent. (Ive watched alot of live deep dive videos, and they encounter ctenophores frequently)

@rebeccawinter472 25 дней назад

Which Ediacaran fauna did the Cambrian phyla (and the phyla extant today) evolve from, I wonder? I know that the link isn’t clear, about how it’s all connected. It’s super fascinating.

@thesjkexperience Год назад

Maybe a video on tectonics and nutrient flux?

@LuisAldamiz 2 года назад

Great one, thanks to you. It has to be a geologist who sets biological evolution up straight? Not really too surprised: you guys know a lot about the Earth's past and not just extracting shale gas. Cheers.

@GEOGIRL 2 года назад

Thanks! Glad you liked this one as much as I do :D And yes, I think every major discovery or breakthrough involves a group effort of scientists from many fields, so I am sure geologists were and still are heavily involved in understanding biological evolution :)

@LuisAldamiz 2 года назад

@@GEOGIRL Yeah, multidisciplinarity is soooooo underrated! And yet so much necessary...

@TonyQinMc Год назад

Are Ediacaran arthropods the ancestors of early trilobites (the Redlichiidas)?

@GEOGIRL Год назад

Yep! :D

@TonyQinMc Год назад

Thank you for your response. You make awesome videos, I real enjoyed watching many of them, especially the ones regarding Paleozoic Era and anything about the Trilobites!

@visvivalaw 9 месяцев назад

Is it accurate to say the survivors of the Cambrian Explosion/Extinction determined (very roughly) the animal body plan of most forms of life on Earth? And if the survivors had been different life here would look very different?

@philochristos Год назад

How do we know that less than 10% of fossils survive? It seems like all we can know about is how many survive, but to know what percentage that amounted to, we would also have to know how many did NOT survive. How could we know that if they didn't survive?

@ramchauhan5238 2 года назад

Very nice prasiontation ..and also best video 😇😇

@GEOGIRL 2 года назад

Thank you! I love this one too, which makes me even happier that you like it as well ;D

@ramchauhan5238 2 года назад

@@GEOGIRL most welcome D😇😇

@isaacfraser4082 Год назад

Do you believe that Intellect of all these Organisms evolved on earth or in The Infinitely old great unknown?

@oqsy Год назад

There certainly seems to be an explosion of “hard parts” if that’s when they first show up. Play whatever word games are needed with the names of the time periods.

@oker59 2 года назад

every time I watch something about ancient life is how many fossils are gone because of plate tectonics!?

@dmbeaster Год назад

A vast number have been destroyed over time. Every time you read about a fossil discovery that has just eroded out so as to become visible to us, countless others have previously eroded out and were destroyed over the vast eons of time.

@oker59 Год назад

@@dmbeaster I learned of nanotechnology in the 80s. Drexler concentrates on the medical, energy, and other benefits of nanotechnology. I've often thought what you could do for Archaeology, Paleontology. One could really analyze all of the Earth to molecular detail

@oker59 Год назад

The orginal nanotech pioneers thought they'd see nano-manufacturing developed in the 1990s, or 2000's at the latest. But, each pathway had "unobtaineum" in their way. Electron microscopes couldn't quite see atoms. Proteins had the protein folding problem. Scanning Tunneling Microscopes could only pick up one atom at a time. I don't think S.T.M's have overcome their problems. But, electron microscopes and proteins have made tremendous breakthroughs! Electrons microscopes have metamaterial optics that overcomes what physical law says they should not do - overcome the electron(and even light) diffraction limit(these metamaterials even have the ability to cloak objects!). The protein folding problem has been practically solved. It hasn't been theoretically solved. There's no deductive proof of protein folding, but they've created A.I. programs that can approximate how amino acids fold into proteins, and to atomic precision!

@oker59 Год назад

I think there could be a surprise from the electron microscope guys(the Oak Ridge boys), but everyone is rightly excited about the protein folding. It's going through the roof! They've gone from taking years to solve a single protein, to, at first ten minutes, now to seconds! They've gone from predicting protein folding, to designing them in the last few months. Alexis Courbet gave a five year timeline to go from proteins, or wet nanotech to a second generation nano-manufacturing. I'm thinking that's a conservative estimate!

@oker59 Год назад

Sorry to go off on a tangent. Hopefully, you found it interesting!

@scambammer6102 Год назад

"cambrian explosion" is what happened after I ate that last tamale

@williamchamberlain2263 Год назад

Primordial ooze

@Svensk7119 10 месяцев назад

Interesting, how you pronounce Ediacaran.

@neddyladdy Год назад

Moving in only one direction is more advanced? By advanced do you mean more modern?

@GEOGIRL Год назад

Not moving in one direction, but being able to direct your movements in a specific direction rather than just kind of going with the waves, sorry if I mispoke ;)

@neddyladdy Год назад

@@GEOGIRL Not moving in one direction? I hope that'a not our favoured direction ! Or maybe you meant moving in all directions but one, all at the same time. Oh aren't I a tease.

@myhatmyseat9924 9 месяцев назад

yep

@erlgunslinger7344 Год назад

Additionally, why do we only find trace fossils of these early burrowers? It seems to me that we should find them in abundance but we only have traces.

@GEOGIRL Год назад

Before skeletons, there is nothing to preserve other than traces ;) The organic material of the actual animal does not get preserved, so we just get the imprints, tracks, and burrows. If you are asking about the skeletonized animals, we do see many body and trace fossils so we have both types because skeletons mineralize and preserve :)

@williamchamberlain2263 Год назад

Plus, maybe (I am entirely unqualified) because the early burrowers were burrowing through the middle and bottom of the pervasive bacterial mats they were covered and continually exposed to bacterial communities which were evolved to deal with anoxic conditions. (Sorry for that horrible sentence structure) So when they died, even within the mud, the bacteria they were carrying on them were happy to decompose the corpse anoxically.

@erlgunslinger7344 Год назад

@@williamchamberlain2263 Makes a lot of sense 👍🏼

@Enkaptaton 2 года назад

What do you mean with "less than 10% of organisms become preserved"? Species?

@GEOGIRL 2 года назад

I think the stat I read was just refering to individual organisms, so if one species is present in a certain environment, 10% of those individuals will become preserved in the rock record. Or I think you can also think of it as refering to biomass, so less than 10% of total biomass becomes preserved in the rock record. Hope that makes sense ;)

@Enkaptaton 2 года назад

@@GEOGIRL So every 10th trilobite became a fossil? Or every 10th one that died I a very special certain environment? It is both kind hard to imagine...

@GEOGIRL 2 года назад

@@Enkaptaton Yes, exactly, about every 10th trilobite would become a fossil, the rest were subject to fragmentation, scavenging, and/or poor preservation conditions. Something that can increase this percentage is the lifestyle of the organism. For example, aquatic organisms have greater preservation potential because those conditions favor preservation more than air-exposed terrestrial environments (aka: a bunny has a lower chance of becoming a fossil than a fish). Another example is humans. Because we bury our dead, we have raised our preservation potential drastically (this is also the reason that more Neanderthals were preserved than other Homo species, because they were one of the only other Homo species that buried their dead). Hope that helps ;)

@Enkaptaton 2 года назад

@@GEOGIRL Thx it helps indeed. I could not believe that the percentage was so high o.O

@LuisAldamiz 2 года назад

@@GEOGIRL - What about different niches being much more or less favorable to preservation? Today we have serious issues re. finding primate or even human remains in places like jungle regions, which are horrible for fossilization but are very important in our paleo-history, I did wonder, as you mentioned this, wether this problem of "enviromental bias" for preservation is considered also for the periods mentioned here like Ediacaran or Cambrian. For example I can imagine that muddy deep sea floor environments would preserve much better than rocky wave-battered coastlines, where however a greater diversity may have been present... but was hard to preserve. Seems like a major issue potentially.

@jbbeiser983 Год назад

Dr.Stephen Meyer wrote THE EXPLOSIVE ORIGIN OF ANIMAL LIFE AND THE CASE FOR INTELLIGENT DESIGN. I did enjoy your video very much thank you .

@duhduhvesta Год назад

Can you give us more examples please ❤

@GEOGIRL Год назад

Sure, examples of what?? haha ;)

@bigwoodvlogs Год назад

I love it when the cute ones are smart

@nicholasmaude6906 Год назад

I thought the Cambrian started 542 MYA?

@GEOGIRL Год назад

I tihnk it used to be defined as 542, and now it is 541 (but I could be getting that backwards) haha ;)

@eaudesolero5631 Год назад

you mispelled explosion in the title

@GEOGIRL Год назад

WOW hahaha I cannot believe you are the first person to point this out to me, THANK YOU! Now it's fixed ;) At least I had it spelled right in the thumbnail lol! 😅

@eaudesolero5631 Год назад

@@GEOGIRL you're welcome. :)

@KoalaMeatPie 2 года назад

CAMBRIAN! YEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEES. Soo. Cool.

@GEOGIRL 2 года назад

I see you like this topic almost as much as I do!! hahaha ;D

@KoalaMeatPie 2 года назад

@@GEOGIRL DUDE! THE DICKINSONIA LIPID STUDIES!?

@petersmythe6462 11 месяцев назад

One wonders if the Cryogenian killed off a lot of stuff that must've been alive during the proterozoic. Perhaps even entire kingdoms of "protist" Eukaryotes.

@sussekind9717 Год назад

4:33 - I don't know if you did that on purpose, or if it was just a fluke, but it's funny either way. "Big dickinsonia", 😉 🤣 Sorry, I can be very juvenile sometimes.

@GEOGIRL Год назад

LOL I did not even notice that until you mentioned it hahaha Now I wish I hadn't said it like that, but oh well 🤣😅

@sussekind9717 Год назад

@@GEOGIRL Don't be too "hard" on yourself. You made me laugh out loud, and that's not easy to do. Professional standup comics, have difficulty doing it. Thanx for making me laugh and smile.😊

@barbaradurfee645 Год назад

Snicker😊

@nomdeguerre7265 Год назад

Vigor is inherent in the fundamental. You might take a look at the Etymology of that relationship too. ;)

@erictaylor5462 Год назад

Could the largest anomalocarids have been a threat to humans if they were extant today?

@GEOGIRL Год назад

Hmm, that's a great question! My guess would be no because they were built to feed on much smaller organisms like trilobites, and they didn't have big mouths like sharks for eating large things, so I doubt they would pose a threat to humans. :)

@ansfridaeyowulfsdottir8095 Год назад

@@GEOGIRL It's pronounced *eddy-AK-a-ran,* not ee-dee-a-KAREN. I'm 9 minutes in, I don't think I can stay the distance if you mispronounce it again too many times. *Edit:* it's OK, I made it! {:o:O:}

@thomaswayneward Год назад

Actually there were many "explosions" where life changed dramatically and suddenly, not just the Cambrian. The origin of life was the first explosion. I am surprised to hear you talk about chemicals being involved or causing the origin of life, as most top scientists have dropped that theory. You do realize that the first replicating life had to be a cell or be made up of cells; since the cell is the most complicated thing in the universe, that we know of, it would have been awfully hard for a bunch of chemicals to form a living cell.

@view1st Год назад

And yet it would appear that they did else we wouldn't be here talking about it.

@thomaswayneward Год назад

@@view1st And your scientific proof is? All you gave is a funny book reply

@danmentink3256 Год назад

So the absorption of calcium carbonate changed the pH of the ocean and plants evolved because of a lack of carbon dioxide.

@toughenupfluffy7294 6 месяцев назад

Dang, I hate it when I do this, but complexation is a chemical reaction process. I believe you mean 'complexification' rather than 'complexation.' Okay, not a grammar Nazi, just trying to be informative...