Hi all, I didn't know I'd have to say this, but after getting so many comments upset with the fact that I leave out invertebrate animals 20 seconds into the video, I feel I should mention that THIS IS THE WHOLE POINT OF THE VIDEO! Please watch the whole video before you comment 'corrections'. My point 20 seconds in is that most people leave out invertebrates when they picture animals, and later in the video, I discuss how important and diverse invertebrates are as animals. I didn't want to say it right away because it kind of gives away the whole question the video ponders. I am sorry if I took too long to get to the point, but just watch the whole video, please! :) Thank you
@GEOGIRL I really do regularly call myself and oðer humans "fish". For example, at ðe breakfast table, I say stuff like "Ðe 📷 👀 of coleoids don't have a blindspot like ðose of us fish".
3:16 whales are mammals, mammals are synapsids, synapsids are tetrapods, tetrapods are lobe finned fish, and lobe finned fish are fish so whales are fish, but also we are fish, penguins are fish, giraffes are fish, etc
Shows what a know-nothing ignoramus my one-year-old daughter was when she corrected an adult who called a whale a fish. "It's not a fish, it's a mammal." Honestly, you'd think she'd have understood cladistics better by that age! (She didn't do too bad in the end, though - she just graduated with the top first in Marine Biology at her university. 🥰)
I'd be happy to see more videos on animal evolution and how it is preserved in the fossil record. Rocks are like little time capsules, and it's amazing how much information geologists have extracted from them. It's especially impressive when our DNA supports the fossil record. Along those lines, I'd like to see your take on the bottleneck our human ancestors hit about 900,000 years ago (if you haven't already discussed it). Keep up the good work. You rock, GeoGirl!
Animal evolution is not preserved in the fossil record. Animals found fossilized appear without precursors. Just because someone tells you one creature evolved from another doesn't make it true.
Moth Light Media is a decent channel for things about evolution from my experience. Otherwise PBS Eons, and Clint’s Reptiles have plenty of videos about evolution.
The thing that a lot of people may miss is that at any given time in our history, there could be a whole bunch of creatures that are wonderfully adapted to their environment with a wide range of features. We’re one of those creatures has one little tiny adaptation that the others don’t have like say a central nerve column seems to give them a slight advantage in organizing the way their body moves, and then a whole bunch of creatures branch out from that, and that original nerve column remains cause it never caused any real problem and then fin arise, and some of them and the fins. A lot of them have like five bony structures that later become our hands, but at each stage, a primitive version of one of these structures gives some creature some marginal success, and that remains in all the rest afterwards, so we’re really a hodgepodge of slowly accumulating character characteristics
I mean, you go back REALLY far, all life is a strand of RNA. :) (At least that was the prevailing theory when I took biology, which was when the periodic table only had 4 elements. Or so it feels sometimes.)
Great video, I've been listening to some audiobooks about early evolution recently and ran into some of these terms like the notochorb but your video helped me understand how that relates to vertebrates.
Thanks for another interesting video! I would love to see another video going into the origins of chordates. Maybe even something more in depth like the evolution from the earliest multicellular animals to chordates? I would also love to see a video about the origins of the arthropods.
I’m so happy that your videos aren’t filled with scientific mubo-jumbo, you break it down so that it’s easy to understand. I don’t know if anyone has thanked you for this, but here’s a big THANK YOU! And God bless!!
Howdy Rachel, thanks for your videos, always interesting and informative. One of my favorite phylum to learn about in early geology classes was Echinodermata. Their typical 5 fold symmetry seemed similar to our four limbs and a head (it’s a stretch I know). Looks like we tie back in the Precambrian, with all kinds of different phylum. Look forward to your deep dives into historical geology.
This video seemed to be so short - it was over too quickly! But then part of that is me enjoying the higher level of intellect in the content (than many other yt videos) while I have lunch. Thanks for another interesting video. Do you have time to dive down that rabbit hole tracing our lineage back to the first multi-celled organism, or even the first single-celled one that we're confident started to clump together for mutual benefit? You definitely have a strong time/task self-discipline.
Some on these concepts are explained in individual videos over on PBS Eons channel =) As we get more concepts together it becomes easier to follow a denser presentation like this one!
After analysis, the ancestor of all fish (including lancelets, lampreys, hagfish and conodonts) was a tiny marine nematode, like Enoplus, in the Ediacaran. That’s where the circle of teeth (or buccal cirri) around the oral cavity came from. Oral tentacles and rasping teeth in hagfish became rasping teeth and tentacles in nautiloids. Lancelets were ancestral to tunicates and echinoderms (like sea cucumbers and starfish, where buccal cirri become arms as they lost their initial bilateral symmetry). Conodonts are derived from lampreys, so they are fish, too. On that note: bony fish had two origins… conodonts gave rise to one branch, the one that extended the jaws as conodonts ectended their tooth rows. Some members, including tetrapods, later developed simple jaws. The other branch began with ostracoderms that evolved into sturgeons. This other branch also gave rise to jawless placoderms which gave rise to a second set of gnathostomes: sharks and catfish + spiny sharks, which evolved to sailfish, salmon, etc. all with simple open-close jaws. So jaws developed at least three times. Cladogram here: reptileevolution.com/reptile-tree.htm
Always excellent, thank you. Conodonts are a fascinating group - so successful for so long, now gone. Were they close relatives or a 'pruned' branch of the chordate tree? A bugbear of mine is I strongly suspect the standard reconstruction with big eyes is wrong... considering their simple neurology large complex eyes would be useless, and what powered their 'extensible mouths'? More likely those 'eyes' were some form of cartridge and they only had eye spots. Some particularly interesting issues surround 'our' early and earliest ancestors. From 'Jawless fish' one seemingly sees three groups arising more-or-less together: Cartilaginous fish, later exemplified by sharks. Placoderms, the first 'jawed' predators that also had a cartilaginous. The Armored bony fish, from which 'we' seem to have arisen... But there in lays a problem: If this is the case that suggests jaws must have arisen more than once; once in the basal cartilaginous fish, and once in the armored fish as they started out without jaws... given how 'novel' real jaws are that seems hard to credit. That also means Placoderms left no descendants. But it seems it is the bony Armored fish that left no descendants, so where did 'we' come from? It seems 'we' are Placoderms who got rid of our skin plates, reengineered our jaws to function without them, and ossified our skeletons. Going much further back it gets 'really' interesting. We are Bilaterians, to which all animals more 'complex' than the likes of sea anemones belong. Bilaterians may be grouped in to Protostomes (mouth-first) and Deuterostomes (anus-first) groups. The latter includes anything with a notochord and starfish-like creatures. The difference lays in the very early embryo, called the blastocyst - what is that first hole going to become? So in a fly that first hole is the mouth, and in 'us' it is our bum! Now comes the fun bit: If Bilaterians evolved before making up their minds; mouth or bum first, then one presumes 'Urbilateria' must have been darn simple creature, as surely for anything remotely complicated changing which end is which is going to be pretty darn catastrophic! But you and I share basic genes for positioning all sorts of complex organs, like eyes with Protostomes like flies and octopuses! How can this be as surely 'changing ends' for a complex Urbilateria would mean it's death? So which is it? Simple, in which case how come Protostomes and Deuterostomes have 'homologous' organs. Or complex, in which case how on Earth could such a creature survive 'changing ends'? I subscribe to the 'Complex Urbilaterian' camp - The trick being prior to the Protostome / Deuterostome spilt the creature was still 'simple' enough not to be reliant on the position of it's blastocyst. So it 'wandered', only becoming necessarily fixed as each lineage got much more complicated - this is the highly simplified version! (One has to consider the evolution of Hox genes hand-in-hand with the relative importance of having an early defined end when considering having a very basic organ vs a more complex one...) More fun? How come creatures with five-pointed symmetry are Deuterostomes when all animals more complex than a coral which has radial symmetry are bilaterians? No, it's not because Deuterostomey is the 'basal' condition - as a 'wandering blastocyst' is the 'basal' condition! It turns out 'starfish' and their kin are 'proper' Deuterostome bilaterians - their embryos swim about like happy little chordates until it's time to 'grow up', at which point they undergo the most amazing game of Twister: Mouth down, bum up, they twist around and loose their notochord along with any other evidence of having been a bilaterian, including their head and brain! Ok, ok, sea lilies are the other way up. I've probably rambled more than enough!
I am really fascinated by the really, really early start to life and where it led, ending at about the Cambrian, so yeah, I'd love a video on where invertebrates came from! Very nice video - thanks!
No, no. You don't have to kid around. Cladistics would forgive you for saying that later fish technically diversified into whales as well as we tetrapods and mammals are all "fish" 😂. But I'd absolutely love a video on the details around the branches between echinoderms, hemichordates, cephalochordates and urochordates before getting to the jawless fish. What blew my mind was realizing how current evidence has vertebrates being more related to things like sea squirts than lancelets based on genetics. This likely meant that a free swimming lancelet-like ancestor must have at some point found it more advantageous to stick its head into the ground reverting to filter feeding as an adult where we could mistake it for a sponge or a sessile cnidarian.
I would absolutely love a video exploring early Deuterostomes! I was actually figuring that was what this video would cover. That seems like one of the most fascinating and mysterious transitions, would love to know the scientific thoughts on it!
This is the interesting thing in astrobiology and speculative biology - they almost always take it as a given that life on other planets or in other worlds would evolve a backbone, even though that is no guarantee. What would life be like on Earth if Notochords never evolved? An interesting thought to ponder.
Yes, I would enjoy a video about that. 570MY ago is soooo far back though. Crazy stuff. I was in Morocco a couple of months back and walking in rocks between 400 and 700MY old. Blew my mind just how old they are. Good Trilobite zone! I do love a sand dollar for your future topic. (Clypeaster reticulatus) Sand dollar is what we called them in UAE. Grew up with lots of them about as a child. I'm from UK but we lived there and I loved finding stuff on the beaches.)
A video is always exciting when it talks about Pikaia. 🥰 This reminds me: have you heard of a classic Super Nintendo RPG called _EVO_ ? It takes many artistic liberties, but in its creation, the game's developers did talk to science teachers about what was known at the time about prehistoric creatures. In it, you start as a fish and, as you gain points, you can use them to purchase "evolutions" such as a bigger horn. Rather than have a child or descendants with mutations unlike yours, you as an individual are what change into an amphibian and then a reptile and then a mammal. You definitely don't want kids to take such depictions literally, especially in how the evolution seems to be portrayed as teleological -- working toward a goal -- which is misleading. But as long as kids are reminded not to take the depiction literally, the classic video game still has aspects that can inspire curiosity about the real science behind evolution. 🥰
I would love a deep dive into the base of bilateria. There are all these worm groups that are the base of every major phylum, mollusks, arthropods and chordates, and both groups have sessile and mobile forms, its a real jumble that is insane to think about.
Yes, a jumble that is insane to think about! That's a great way to describe it ;) Haha But yes, I will absolutely try to do a follow up video on that ;D
so the contradiction of "no such thing as a fish" is "all animals are fish" since the deep ancestor is a fish? (and thus all mammals are fish and *obviously* whales are fish)
Ahh! awsome.. how have you gone under the radar? Love the huge refference lists. Hate writing them, but love seeing that folks have done the research :) Upto now, the only other channels ive liked is Trey, And 7DOS.. and some of Kailys stuff.
I learned about the fishes from the old TV series "Lucky Louis" by Louis CK. In one episode a character named Norton explains the origin of species. Found on YT still. An explanation of the origin of every living thing.
3:16 Whales are mammals but mammals are fishes (because the last common ancestor off all fishes is also the ancestor of all terrestrial vertebrates), so whales are fish. It's the same reason why apes are monkeys and birds are dinosaurs: you can't evolve out of a clade. In fact most fishes that swim in the ocean are more closely related to whales than they are to sharks.
You guys will discover that evolution largely occurs during early developmental stages, see the amazing work of Mary Jane West-Eberhard about 21 and more years ago. The embryonic forms of chordates are similar in development, and we are more like the others than too many will admit, including in brains, behaviors, and specific genes that control genes. In spite of HER screenname, Geogirl will likely 'splain all this and more over time. i stand, due to my vertebrae, in awe..
When I first saw the first few words of the title, "If We All Came From Fish," I thought the rest of the title was going to be "Then Why Are There Still Fish?" 😉 As my uncle used to say, "If we all came from fishes, then why are there still fishes?" 😉🐟
I was going to ask that as a joke. It’s a common trope with creationists. There goes for us being apes, which Erica Gutsick Gibbon and others bat away regularly.
Paleobiologists tell us that modern fish are not the same fish as fish from millions of years ago. To call a modern animals that resemble it's ancient ancestors "living fossils" is misleading because they have evolved from other fish while still looking like their ancestors.
Always nice to sit back and take a look at our ancestors. We have come so far. Where will we be in another 500 million years? Perhaps we will have wings and will fly.
1:28 ✅️ 👍 At last, someone points out on YT ðat conodonts are likely no 🐟. Specifically, conodont teeþ are unrelated to 🐟 teeþ, as shown by S. Turner et al. in *False teeth: conodont-vertebrate phylogenetic relationships revisited* . Þank you for anoðer informative video! 😃
@@GEOGIRL by win i meant like dominant. It seems vertebrates are higher up on the food chain than invertebrates. Unless i don't understand it properly.
What do you mean, do we want to see another video, extending the subject matter of this one?? Of course we do! Plus, you suggested it, so we're already waiting for it ... Thanks in advance! 👾
If I could choose a sea creature to be related to, it would be the sea horse. Strong childhood memories of La Jolla summers and the sea horses on display in the Marine Room next to the La Jolla Beach & Tennis Club of the 1950s.
Haikouichtys and Myllokunmingia are craniates, that is cephalocordates, like the modern hagfish and lampreys, but Pikaia appears to be more primitive, although it is roughly contemporary with the other two, and it may not be a true craniate and anyway not the ancestor of all vertebrates as was previously thought by some. Fascinating topic dear Rachel!
monophyletically speaking, if you're saying that cartilogenous fish are "fish", and also bony fish are "fish", then mammals are also fish (since every bony fish is more closely related to any mammal than to any cartiologenous fish). yes, whales are fish. so are we. there's even books written about it: Neil Shubin : Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body. it's just that the word "fish" is normally not used as a phylum. anyway, monophyly is the single most coherent way to categorize life, so either we stop using the word "fish" (just like the "berry" in strawberry doesn't mean anything), or we count ourselves in (obviously, the preferred way forward).
Yes, please explore the subject of developing the cordage ancestors. I have found very little about the gap between worms and early cordates. Another interesting subject would be the difference between the invertebrate cordates and invertebrates like arthropods. It looks like the main difference is the position of digestive tract and notocord/ganglia. In cordates the notocord is on the back and the colon on the belly, while in arthropods it is vice versa. Another major difference seems to be that arthropods do not appear to have a circulatory system or a dedicated gas exchange organ like gills or lungs. Is that correct? When did these gas exchange organs develop in cordates? A lot ofquedtions that I hope we might see some knteresting vids of soon. Thank you for your excellent content.
Most arthropods have a linear multi-chambered heart along the abdomen that pumps blood forward toward the thorax and head. They have an "open" circulatory system, meaning there are no capillaries. Instead the blood flows in the spaces around the internal organs and back to the heart. Land arthropods (insects and arachnids) do have a respiratory system in the form of "trachea", short tubes that run in pairs along the abdomen and allow gas exchange with the air. If you watch a wasp up close you can see its abdomen pulsating, pumping air in and out of its trachea. Chordate gills were originally for filter feeding, but as the body size increased, it became convenient to use the constant flow of water over the gills for gas exchange, so they became specialized for respiration. Lungs probably evolved as thin-skinned pouches in the back of the throat of fish that lived in shallow, poorly oxidized water that developed the habit of gulping a mouthful of air for extra oxygen. As this way of respiration became more important the pouches would branch and grow down into the chest, becoming lungs. The air-gulping reflex still exists inside us as the hiccup.
From a phylogeny standpoint, there is nothing wrong with calling whales - or any other tetrapod - a fish. Whales are more closely related to trout, than trout are to sharks.
What is your opinion on species that evolve into an invasive position being sub-categorized differently? House Sparrows have 4 genes- adaptations that derived from humans inventing farming 20,000 years ago; I was hesitant in a recent presentation to my professor (also Rachel) to call them "invasive" and not a "rotation of natural order".
Hi all, I didn't know I'd have to say this, but after getting so many comments upset with the fact that I leave out invertebrate animals 20 seconds into the video, I feel I should mention that THIS IS THE WHOLE POINT OF THE VIDEO! Please watch the whole video before you comment 'corrections'. My point 20 seconds in is that most people leave out invertebrates when they picture animals, and later in the video, I discuss how important and diverse invertebrates are as animals. I didn't want to say it right away because it kind of gives away the whole question the video ponders. I am sorry if I took too long to get to the point, but just watch the whole video, please! :) Thank you
@GEOGIRL I really do regularly call myself and oðer humans "fish". For example, at ðe breakfast table, I say stuff like "Ðe 📷 👀 of coleoids don't have a blindspot like ðose of us fish".
@@GEOGIRL 👍
@@GEOGIRL wohoo
most people are stupid.
@ GEOGIRL. I just discovered your channel. Awesome video
3:16 whales are mammals, mammals are synapsids, synapsids are tetrapods, tetrapods are lobe finned fish, and lobe finned fish are fish
so whales are fish, but also we are fish, penguins are fish, giraffes are fish, etc
I don't know, sounds fishy to me...
Shows what a know-nothing ignoramus my one-year-old daughter was when she corrected an adult who called a whale a fish. "It's not a fish, it's a mammal." Honestly, you'd think she'd have understood cladistics better by that age! (She didn't do too bad in the end, though - she just graduated with the top first in Marine Biology at her university. 🥰)
@@elvwood Trying to evolove out of a clade ... or did whales try to evolve back because they thought they evolved out of it? We will never know...
@@twipameyer1210 But evolution is not about "trying" or "wanting".
@@Szejski Evolution does not but whales did. Think about it. Or don't, it doesn't make much sense anyway.
As a land fish myself, I have to say I really like this video.
Finally someone who uses ðe same terminology I do 👏! I routinely call myself "a land 🐟 ".
I'd be happy to see more videos on animal evolution and how it is preserved in the fossil record. Rocks are like little time capsules, and it's amazing how much information geologists have extracted from them. It's especially impressive when our DNA supports the fossil record. Along those lines, I'd like to see your take on the bottleneck our human ancestors hit about 900,000 years ago (if you haven't already discussed it). Keep up the good work. You rock, GeoGirl!
Animal evolution is not preserved in the fossil record. Animals found fossilized appear without precursors. Just because someone tells you one creature evolved from another doesn't make it true.
Moth Light Media is a decent channel for things about evolution from my experience. Otherwise PBS Eons, and Clint’s Reptiles have plenty of videos about evolution.
😊
Prefish: I may lack jaws and a skeleton, but my googly eyes r pretty cute.
Haha so true 😂
I just woke up and relate so much to the Conodont on the right at 1:08 currently
😂
This was highly educational and fascinating. Great work!
The thing that a lot of people may miss is that at any given time in our history, there could be a whole bunch of creatures that are wonderfully adapted to their environment with a wide range of features. We’re one of those creatures has one little tiny adaptation that the others don’t have like say a central nerve column seems to give them a slight advantage in organizing the way their body moves, and then a whole bunch of creatures branch out from that, and that original nerve column remains cause it never caused any real problem and then fin arise, and some of them and the fins. A lot of them have like five bony structures that later become our hands, but at each stage, a primitive version of one of these structures gives some creature some marginal success, and that remains in all the rest afterwards, so we’re really a hodgepodge of slowly accumulating character characteristics
That's true. The periodic oxia-anoxia and predator-prey chains probably "selected for" the best adapted fish.
Another excellent session that Koda and I listened to together ❤🐕
Another great video from Geo Girl. What a fascinating topic. Thanks, as always, for sharing your knowledge with us.
As always great video GeoGirl, thanks!
Gotta love the notochord. I always look forward to a GeoGirl video.
Fabulous stuff as always Geo Girl! Thanks so much for the wonderful channel. Great topic. Loved that. So interesting.
I do enjoy the fact that if you go far back enough, all earths rich biodiversity is just different types of worms
I mean, you go back REALLY far, all life is a strand of RNA. :) (At least that was the prevailing theory when I took biology, which was when the periodic table only had 4 elements. Or so it feels sometimes.)
Even farther: viruses.
I really enjoy researching about prehistoric life and understanding the origins of different species
Good Morning Rachel 🌄,
This is a super clever video! Fascinating! 🙏.
I'd vote for more please.
👏👏👏👏👏
Thank you so much! Glad to hear that ;D
Yes, please do continue. I am quite interested in this topic, going all the way back to the beginning with choanoflagellates.
Great video, I've been listening to some audiobooks about early evolution recently and ran into some of these terms like the notochorb but your video helped me understand how that relates to vertebrates.
Thanks for another interesting video! I would love to see another video going into the origins of chordates. Maybe even something more in depth like the evolution from the earliest multicellular animals to chordates? I would also love to see a video about the origins of the arthropods.
Amazing video Rachel 👏. I got into geology because I love fossils.
Thanks! That's awesome ;D Fossils are so cool (both alone just as structures, but also because of the stories they tell!)
3:13 „Whales“ - Technically true, the best kind of true.
They're also even-toed ungulates. Which makes sense, because zero is an even number.
Just subscribed. Great video.
You're the best Geo-Girl, and I definitely vote for the follow up on invertebrate evolution! It's such a fascinating topic😊
I’m so happy that your videos aren’t filled with scientific mubo-jumbo, you break it down so that it’s easy to understand. I don’t know if anyone has thanked you for this, but here’s a big THANK YOU! And God bless!!
Thank you so much! So glad to hear that ;D
great video Dr geo girl thank you
Love this video Rachel. I love geology & evolution...so this hits the spot v well 🙂😘
Howdy Rachel, thanks for your videos, always interesting and informative. One of my favorite phylum to learn about in early geology classes was Echinodermata. Their typical 5 fold symmetry seemed similar to our four limbs and a head (it’s a stretch I know). Looks like we tie back in the Precambrian, with all kinds of different phylum. Look forward to your deep dives into historical geology.
Love this topic! More please!
This video seemed to be so short - it was over too quickly! But then part of that is me enjoying the higher level of intellect in the content (than many other yt videos) while I have lunch. Thanks for another interesting video. Do you have time to dive down that rabbit hole tracing our lineage back to the first multi-celled organism, or even the first single-celled one that we're confident started to clump together for mutual benefit? You definitely have a strong time/task self-discipline.
Geo Girl is so fascinating just like her videos! ❤🎉😊
Please do it. You do great work on everything you dive into. Thanks!
Lots of information, I couldn't keep up. Still, it is fascinating. Thanks.
Some on these concepts are explained in individual videos over on PBS Eons channel =)
As we get more concepts together it becomes easier to follow a denser presentation like this one!
Very interesting and educational, thank you 🌹
After analysis, the ancestor of all fish (including lancelets, lampreys, hagfish and conodonts) was a tiny marine nematode, like Enoplus, in the Ediacaran. That’s where the circle of teeth (or buccal cirri) around the oral cavity came from. Oral tentacles and rasping teeth in hagfish became rasping teeth and tentacles in nautiloids. Lancelets were ancestral to tunicates and echinoderms (like sea cucumbers and starfish, where buccal cirri become arms as they lost their initial bilateral symmetry). Conodonts are derived from lampreys, so they are fish, too.
On that note: bony fish had two origins… conodonts gave rise to one branch, the one that extended the jaws as conodonts ectended their tooth rows. Some members, including tetrapods, later developed simple jaws.
The other branch began with ostracoderms that evolved into sturgeons. This other branch also gave rise to jawless placoderms which gave rise to a second set of gnathostomes: sharks and catfish + spiny sharks, which evolved to sailfish, salmon, etc. all with simple open-close jaws. So jaws developed at least three times.
Cladogram here: reptileevolution.com/reptile-tree.htm
A new Geo Girl video - made my Sunday, Rachel! 🐟🪨🌺
Yay! So glad to hear that ;)
Always excellent, thank you.
Conodonts are a fascinating group - so successful for so long, now gone. Were they close relatives or a 'pruned' branch of the chordate tree? A bugbear of mine is I strongly suspect the standard reconstruction with big eyes is wrong... considering their simple neurology large complex eyes would be useless, and what powered their 'extensible mouths'? More likely those 'eyes' were some form of cartridge and they only had eye spots.
Some particularly interesting issues surround 'our' early and earliest ancestors.
From 'Jawless fish' one seemingly sees three groups arising more-or-less together: Cartilaginous fish, later exemplified by sharks. Placoderms, the first 'jawed' predators that also had a cartilaginous. The Armored bony fish, from which 'we' seem to have arisen... But there in lays a problem:
If this is the case that suggests jaws must have arisen more than once; once in the basal cartilaginous fish, and once in the armored fish as they started out without jaws... given how 'novel' real jaws are that seems hard to credit. That also means Placoderms left no descendants.
But it seems it is the bony Armored fish that left no descendants, so where did 'we' come from? It seems 'we' are Placoderms who got rid of our skin plates, reengineered our jaws to function without them, and ossified our skeletons.
Going much further back it gets 'really' interesting. We are Bilaterians, to which all animals more 'complex' than the likes of sea anemones belong. Bilaterians may be grouped in to Protostomes (mouth-first) and Deuterostomes (anus-first) groups. The latter includes anything with a notochord and starfish-like creatures. The difference lays in the very early embryo, called the blastocyst - what is that first hole going to become? So in a fly that first hole is the mouth, and in 'us' it is our bum! Now comes the fun bit:
If Bilaterians evolved before making up their minds; mouth or bum first, then one presumes 'Urbilateria' must have been darn simple creature, as surely for anything remotely complicated changing which end is which is going to be pretty darn catastrophic! But you and I share basic genes for positioning all sorts of complex organs, like eyes with Protostomes like flies and octopuses! How can this be as surely 'changing ends' for a complex Urbilateria would mean it's death?
So which is it? Simple, in which case how come Protostomes and Deuterostomes have 'homologous' organs. Or complex, in which case how on Earth could such a creature survive 'changing ends'?
I subscribe to the 'Complex Urbilaterian' camp - The trick being prior to the Protostome / Deuterostome spilt the creature was still 'simple' enough not to be reliant on the position of it's blastocyst. So it 'wandered', only becoming necessarily fixed as each lineage got much more complicated - this is the highly simplified version! (One has to consider the evolution of Hox genes hand-in-hand with the relative importance of having an early defined end when considering having a very basic organ vs a more complex one...)
More fun? How come creatures with five-pointed symmetry are Deuterostomes when all animals more complex than a coral which has radial symmetry are bilaterians? No, it's not because Deuterostomey is the 'basal' condition - as a 'wandering blastocyst' is the 'basal' condition!
It turns out 'starfish' and their kin are 'proper' Deuterostome bilaterians - their embryos swim about like happy little chordates until it's time to 'grow up', at which point they undergo the most amazing game of Twister: Mouth down, bum up, they twist around and loose their notochord along with any other evidence of having been a bilaterian, including their head and brain! Ok, ok, sea lilies are the other way up.
I've probably rambled more than enough!
I would love to see another video like this.
I am really fascinated by the really, really early start to life and where it led, ending at about the Cambrian, so yeah, I'd love a video on where invertebrates came from! Very nice video - thanks!
I like the summarization you present. You make it easy to understand. You are establishing a channel well worth listening to. 😊
This is why I follow GEO GIRL. GEO GIRL talks are original to me.
No, no. You don't have to kid around. Cladistics would forgive you for saying that later fish technically diversified into whales as well as we tetrapods and mammals are all "fish" 😂.
But I'd absolutely love a video on the details around the branches between echinoderms, hemichordates, cephalochordates and urochordates before getting to the jawless fish. What blew my mind was realizing how current evidence has vertebrates being more related to things like sea squirts than lancelets based on genetics. This likely meant that a free swimming lancelet-like ancestor must have at some point found it more advantageous to stick its head into the ground reverting to filter feeding as an adult where we could mistake it for a sponge or a sessile cnidarian.
Thanks for the video!
Good video. Geo girl needs to present more videos. Much more thought inspiring than politics
As a highly derived lobe finned fish myself, I approve this video.
Please do explore the whole deuterostoma development, what might be the last common ancestor to both prostoma and deyterostoma.
So I'm more closely related to a starfish than a bumblebee. Wild!
I know right! :D So cool!!
I would absolutely love a video exploring early Deuterostomes! I was actually figuring that was what this video would cover. That seems like one of the most fascinating and mysterious transitions, would love to know the scientific thoughts on it!
Geogirl is my favorite bony fish on RUclips ❤
Best compliment I've ever recieved ;)
0:21 invertebrates: am I a joke to you?
Haha, that's the point I am trying to make with that slide (I just kinda delayed the answer til later in the video ;)
@@GEOGIRL yeah, I made that comment when I just started the vid lol
Thanks for the education!
Thank you for the video ! Very interesting
This is the interesting thing in astrobiology and speculative biology - they almost always take it as a given that life on other planets or in other worlds would evolve a backbone, even though that is no guarantee. What would life be like on Earth if Notochords never evolved? An interesting thought to ponder.
Please do a video on Garstang's hypothesis.
Thanks again GG......that was illuminating.
Thanks! So glad you enjoyed it :)
Very interesting and educational. Well done. Thank you. Made me want to hear more.
Yes, I would enjoy a video about that. 570MY ago is soooo far back though. Crazy stuff. I was in Morocco a couple of months back and walking in rocks between 400 and 700MY old. Blew my mind just how old they are. Good Trilobite zone! I do love a sand dollar for your future topic. (Clypeaster reticulatus) Sand dollar is what we called them in UAE. Grew up with lots of them about as a child. I'm from UK but we lived there and I loved finding stuff on the beaches.)
Great vid! Looking forward to more early animal evolution videos
A video is always exciting when it talks about Pikaia. 🥰
This reminds me: have you heard of a classic Super Nintendo RPG called _EVO_ ? It takes many artistic liberties, but in its creation, the game's developers did talk to science teachers about what was known at the time about prehistoric creatures. In it, you start as a fish and, as you gain points, you can use them to purchase "evolutions" such as a bigger horn. Rather than have a child or descendants with mutations unlike yours, you as an individual are what change into an amphibian and then a reptile and then a mammal. You definitely don't want kids to take such depictions literally, especially in how the evolution seems to be portrayed as teleological -- working toward a goal -- which is misleading. But as long as kids are reminded not to take the depiction literally, the classic video game still has aspects that can inspire curiosity about the real science behind evolution. 🥰
Yes, please do a video on what has been discovered about the earliest ancestral lineages bridging the phyla. I know there are recent breakthroughs.
I would love a deep dive into the base of bilateria. There are all these worm groups that are the base of every major phylum, mollusks, arthropods and chordates, and both groups have sessile and mobile forms, its a real jumble that is insane to think about.
Yes, a jumble that is insane to think about! That's a great way to describe it ;) Haha But yes, I will absolutely try to do a follow up video on that ;D
PSB should start a show with you
Omg that’s been my dream for eons (pun intended) 😍
@@GEOGIRL loool, imma send them an email 🫠👍
so the contradiction of "no such thing as a fish" is "all animals are fish" since the deep ancestor is a fish? (and thus all mammals are fish and *obviously* whales are fish)
Whales are indeed mammals. . . but surely mammals are fish?
Ahh! awsome.. how have you gone under the radar? Love the huge refference lists. Hate writing them, but love seeing that folks have done the research :)
Upto now, the only other channels ive liked is Trey, And 7DOS.. and some of Kailys stuff.
It's interesting hearing someone mention grades rather than just clades.
I learned about the fishes from the old TV series "Lucky Louis" by Louis CK. In one episode a character named Norton explains the origin of species. Found on YT still. An explanation of the origin of every living thing.
3:16
Whales are mammals but mammals are fishes (because the last common ancestor off all fishes is also the ancestor of all terrestrial vertebrates), so whales are fish. It's the same reason why apes are monkeys and birds are dinosaurs: you can't evolve out of a clade.
In fact most fishes that swim in the ocean are more closely related to whales than they are to sharks.
You guys will discover that evolution largely occurs during early developmental stages, see the amazing work of Mary Jane West-Eberhard about 21 and more years ago.
The embryonic forms of chordates are similar in development, and we are more like the others than too many will admit, including in brains, behaviors, and specific genes that control genes.
In spite of HER screenname, Geogirl will likely 'splain all this and more over time. i stand, due to my vertebrae, in awe..
Good video!👌👏🔝💯
When I first saw the first few words of the title, "If We All Came From Fish," I thought the rest of the title was going to be "Then Why Are There Still Fish?" 😉
As my uncle used to say, "If we all came from fishes, then why are there still fishes?" 😉🐟
I was going to ask that as a joke. It’s a common trope with creationists. There goes for us being apes, which Erica Gutsick Gibbon and others bat away regularly.
@@bf99ls You explained why I thought my joke was funny. 😅
Paleobiologists tell us that modern fish are not the same fish as fish from millions of years ago. To call a modern animals that resemble it's ancient ancestors "living fossils" is misleading because they have evolved from other fish while still looking like their ancestors.
3:17 I mean technically whales are a type of highly derived lobe finned fish (like all tetrapods) so is it a lie?
You got me with that Whales mention , I was like "what? whales!?"
Always nice to sit back and take a look at our ancestors. We have come so far. Where will we be in another 500 million years? Perhaps we will have wings and will fly.
Always fun to think what adaptations may come in the future! ;D
Awesome video! Have the nasal sacs in Haikouichthys been confirmed?
1:28 ✅️ 👍 At last, someone points out on YT ðat conodonts are likely no 🐟. Specifically, conodont teeþ are unrelated to 🐟 teeþ, as shown by S. Turner et al. in *False teeth: conodont-vertebrate phylogenetic relationships revisited* . Þank you for anoðer informative video! 😃
hi i am from somalia and i just take this lesson today from university and when i came to home at night you just posted this video thanks
Seeing the evolution of ideas among a team of genetic engineers in labcoats now millions of years old and feeling underrated, oh well
So why did vertebrates win? It seems an exoskeleton is more protective.
No sure what you mean 'win'? Invertebrates were and still are much more diverse than vertebrates :)
@@GEOGIRL by win i meant like dominant. It seems vertebrates are higher up on the food chain than invertebrates. Unless i don't understand it properly.
Ðe first *mineralized* and hard vertebrate skeleton *was* exo.
What do you mean, do we want to see another video, extending the subject matter of this one?? Of course we do! Plus, you suggested it, so we're already waiting for it ... Thanks in advance! 👾
On the way! ;D
If I saw an ostracoderms fish while swimming , I wouldn’t get within a mile of the ocean ever again. 😮
If I could choose a sea creature to be related to, it would be the sea horse. Strong childhood memories of La Jolla summers and the sea horses on display in the Marine Room next to the La Jolla Beach & Tennis Club of the 1950s.
4:30 This looks like a future graphic of living things discovered in Europa.
thanks for the content :D
Of course! Glad you enjoyed it ;D
That conodont somehow looks goofy and terrifying at the same time.
I'll listen and watch to what ever your heart wants to talk about, to educate us
yes. future vid on non-verts to verts, please.
Lancelet or amphioxus is a living animal, where you can see it as the precursor of fish.
Please tell me youre doing the evolution of jaws next.... The way I explain Deuterosome taxonomy is the progress to a full chordate body plan
@GEOGIRL - If you had some sort of time-travel machine, Rachel, would travel to the Devonian for a bit of fishing😉😁?
Modern evidence of evolution in mammals: seals, sea lions, manatees, dugongs,
Nice video. May I request a topic. Deep large reservoirs of water in our planet. Thank you.
Haikouichtys and Myllokunmingia are craniates, that is cephalocordates, like the modern hagfish and lampreys, but Pikaia appears to be more primitive, although it is roughly contemporary with the other two, and it may not be a true craniate and anyway not the ancestor of all vertebrates as was previously thought by some. Fascinating topic dear Rachel!
monophyletically speaking, if you're saying that cartilogenous fish are "fish", and also bony fish are "fish", then mammals are also fish (since every bony fish is more closely related to any mammal than to any cartiologenous fish).
yes, whales are fish. so are we. there's even books written about it: Neil Shubin : Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body.
it's just that the word "fish" is normally not used as a phylum. anyway, monophyly is the single most coherent way to categorize life, so either we stop using the word "fish" (just like the "berry" in strawberry doesn't mean anything), or we count ourselves in (obviously, the preferred way forward).
"then mammals are also fish "
Yes, please explore the subject of developing the cordage ancestors. I have found very little about the gap between worms and early cordates.
Another interesting subject would be the difference between the invertebrate cordates and invertebrates like arthropods. It looks like the main difference is the position of digestive tract and notocord/ganglia. In cordates the notocord is on the back and the colon on the belly, while in arthropods it is vice versa.
Another major difference seems to be that arthropods do not appear to have a circulatory system or a dedicated gas exchange organ like gills or lungs. Is that correct?
When did these gas exchange organs develop in cordates?
A lot ofquedtions that I hope we might see some knteresting vids of soon.
Thank you for your excellent content.
Most arthropods have a linear multi-chambered heart along the abdomen that pumps blood forward toward the thorax and head. They have an "open" circulatory system, meaning there are no capillaries. Instead the blood flows in the spaces around the internal organs and back to the heart.
Land arthropods (insects and arachnids) do have a respiratory system in the form of "trachea", short tubes that run in pairs along the abdomen and allow gas exchange with the air. If you watch a wasp up close you can see its abdomen pulsating, pumping air in and out of its trachea.
Chordate gills were originally for filter feeding, but as the body size increased, it became convenient to use the constant flow of water over the gills for gas exchange, so they became specialized for respiration.
Lungs probably evolved as thin-skinned pouches in the back of the throat of fish that lived in shallow, poorly oxidized water that developed the habit of gulping a mouthful of air for extra oxygen. As this way of respiration became more important the pouches would branch and grow down into the chest, becoming lungs. The air-gulping reflex still exists inside us as the hiccup.
@@mosquitobight Yhank you for this detailed answer. That is great info.
From a phylogeny standpoint, there is nothing wrong with calling whales - or any other tetrapod - a fish. Whales are more closely related to trout, than trout are to sharks.
What is your opinion on species that evolve into an invasive position being sub-categorized differently? House Sparrows have 4 genes- adaptations that derived from humans inventing farming 20,000 years ago; I was hesitant in a recent presentation to my professor (also Rachel) to call them "invasive" and not a "rotation of natural order".
Super interesting🤓👍🏻👏🏻
Fish comes from fish egg.
Fish egg comes from mommy fish.
Yes please, further back in the history of life!
Oh great . She used my DMV photo for the conodonts example
😂