How the Chalicothere Split In Two

  • Publicado el 24 abr 2018
  • Try CuriosityStream today:
    Two extinct relatives of horses and rhinos are closely related to each other but have strikingly different body plans. How did two of the same kind of animal, living in the same place, end up looking so different?
    Thanks to Ceri Thomas for the very cool Anisodon reconstruction. Check out more of Ceri's paleoart at and
    And thanks as always to Nobumichi Tamura for allowing us to use his wonderful paleoart:
    Finally, thanks to Dmitry Bogdanov, Roman Uchytel, Ryan Somma and Julio Lacerda for their excellent images as well.
    Produced in collaboration with PBS Digital Studios:
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    Prothero, D. R., & Schoch, R. M. (1989). The evolution of perissodactyls (Vol. 15). Oxford University Press, USA.
    Peters, N., & de Vos, J. (2012). First evidence of a chalicothere (Mammalia, Perissodactyla) in The Netherlands. Cainozoic research, 9(2), 141-144.
    Clauss, M., Frey, R., Kiefer, B., Lechner-Doll, M., Loehlein, W., Polster, C., ... & Streich, W. J. (2003). The maximum attainable body size of herbivorous mammals: morphophysiological constraints on foregut, and adaptations of hindgut fermenters. Oecologia, 136(1), 14-27.
    Heaney, L. R. (1991). A synopsis of climatic and vegetational change in Southeast Asia. In Tropical Forests and Climate (pp. 53-61). Springer, Dordrecht.
    Churcher, C. S. (2014). A vacant niche? The curious distributions of African Perissodactyla. Transactions of the Royal Society of South Africa, 69(1), 1-8.
    Werdelin, L., & Sanders, W. J. (2010). Cenozoic mammals of Africa. Univ of California Press.
    Colbert, H. (1935). Distributional and phylogenetic studies on Indian fossil mammals. III. A classification of the Chalicotherioidea. In American Museum Novitates.
    Bai, B., Wang, Y., & Meng, J. (2011). Early Eocene chalicothere Litolophus with hoof-like unguals. Journal of Vertebrate Paleontology, 31(6), 1387-1391.
    Peterson, O. A. (1907). Preliminary notes on some American chalicotheres. The American Naturalist, 41(492), 733-752.
    Munthe, J., & Coombs, M. C. (1979). Miocene dome-skulled chalicotheres (Mammalia, Perissodactyla) from the western United States: a preliminary discussion of a bizarre structure. Journal of Paleontology, 77-91.
    Janis, C. M., Scott, K. M., & Jacobs, L. L. (Eds.). (1998). Evolution of tertiary mammals of North America: Volume 1, terrestrial carnivores, ungulates, and ungulate like mammals (Vol. 1). Cambridge University Press.
    Coombs, M. C., & Rothschild, B. M. (1999). Phalangeal fusion in schizotheriine chalicotheres (Mammalia, Perissodactyla). Journal of Paleontology, 73(4), 682-690.
    Coombs, M. C., Hunt Jr, R. M., Stepleton, E., ALBRIGHT III, L. B., & Fremd, T. J. (2001). Stratigraphy, chronology, biogeography, and taxonomy of early Miocene small chalicotheres in North America. Journal of Vertebrate Paleontology, 21(3), 607-620.
    Coombs, M. C. (1979). Tylocephalonyx, a new genus of North American dome-skulled chalicotheres (Mammalia, Perissodactyla). Bulletin of the AMNH; v. 164, article 1.
    Coombs, M. C. (1975). Sexual dimorphism in chalicotheres (Mammalia, Perissodactyla). Systematic Biology, 24(1), 55-62.
    Semprebon, G. M., Sise, P. J., & Coombs, M. C. (2011). Potential bark and fruit browsing as revealed by stereomicrowear analysis of the peculiar clawed herbivores known as chalicotheres (Perissodactyla, Chalicotherioidea). Journal of Mammalian Evolution, 18(1), 33-55.
    Zapfe, H. 1976. "Die Fauna der miozanen Spaltenfiillung von Neudorf a. d. March (CSSR). Chalicotherium grande (Blv.)." Sitzungsberichte Osterreich Akad. Wissenschaften, Math.-na-turwiss. Klasse (Abt. I) 185: 91-112.
    Zapf 1979. "Chalicotherium grande (Blainv.) aus der miozanen Spaltenfiillung von Neudorf an der March (Devinska Nova Ves), Tschechoslowakei." Neue Denkschriften Naturhist. Mus. Wien 2: 1-282. Zhou, Mingzhun, Yu
    Munthe, J., & Coombs, M. C. (1979). Miocene dome-skulled chalicotheres (Mammalia, Perissodactyla) from the western United States: a preliminary discussion of a bizarre structure. Journal of Paleontology, 77-91.
    Wunderlich, R. E., and W. L. Jungers. "Manual digital pressures during knuckle-walking in chimpanzees (Pan troglodytes)." American journal of physical anthropology 139.3 (2009): 394-403.
  • Ciencia y tecnologíaCiencia y tecnología

Comentarios • 832

  • Heru Setiawan
    Heru Setiawan Hace un día

    Well talking about splitting.
    Look at dogs.

  • Keys879
    Keys879 Hace 2 días

    All I can think while watching this is: "Damn, Spore could have been so cool..."

  • pizza 4breakfast
    pizza 4breakfast Hace 4 días +1

    Long-armed knuckle-walker, my new favorite insult

  • vin 950
    vin 950 Hace 11 días

    but why didn't each type reproduce together? Was there an eventual geographical split?

  • God Of War
    God Of War Hace 14 días

    Evolution is key to our survival

  • luciables
    luciables Hace 15 días

    Cooooool!! Can you also do a video on rumens and the mammals that have four stomachs and how that came to be? Is there already one?

  • Comic Book Guy
    Comic Book Guy Hace 16 días

    So how the heck did ancestor of deer, cattle, hippos, etc evolve four stomachs? How do you go from one stomach to four, in small increments of mutational change which, in themselves, aren't really advantageous?

    • worfoz
      worfoz Hace un día +1

      It's more like the stomach decided into four compartments.
      But now having these ruminants is a huge is advantage because they produce huge amounts of greenhouse gas.
      They should be outlawed.

  • Bmh
    Bmh Hace 16 días


  • cacadodo666
    cacadodo666 Hace 16 días

    'How the Chalicothere MIGHT HAVE Split In Two'

  • Decembirth
    Decembirth Hace 16 días

    Honestly thought this would be about trees.

  • C B
    C B Hace 19 días

    Hank, I'm confused. Did the Chalicos die out, while horses and rhinos, which existed cotemporaly with Chalicos, carried on in their place? (This seems to be what your closing remarks imply.) Or did the Chalicos evolve into horses (one strain) and rhinos (the other strain)? If the latter, then why use the phrase "they couldn't survive"? They did survive, but only the horsey or rhino-y ones, didn't they? Evolution did "get them out of" their situation (i.e. changing habitat). Am I missing something?

  • GhostlyGhille
    GhostlyGhille Hace 20 días +1

    This show deserves primetime spotlight, not reality show B's. Not even discovery channel teaches anymore.

  • Shin Nightwood
    Shin Nightwood Hace 20 días

    Did these two types interbred?

  • 5chr4pn3ll
    5chr4pn3ll Hace 21 un día

    These are really good videos. Great balance of accessibility and information, if only the videos were longer

  • Rebecca Conn
    Rebecca Conn Hace 23 días

    What about urbanization such that human beings do not know what is edible in their own environment?

  • Marcel Klein
    Marcel Klein Hace 26 días

    Do an episode about Andrewsarchus, an enormous carnivorous pig that looked like a wolf but was bigger than a bear.

  • Robert Chavez
    Robert Chavez Hace 26 días

    Humans are specialized in depending on electricity and our technology let's see how long we last

  • Sharof S.
    Sharof S. Hace 27 días

    So, they should have evolved their intestines instead of developing claws?

  • Ariana Negron
    Ariana Negron Hace 27 días +1

    i love eons and might consider the things that sponsor it
    but too bad im a poor american college student

  • The Mr. Jones Show
    The Mr. Jones Show Hace un mes

    I'm here because I was looking up how to tame a Chalico in Ark

  • Conrado Javier
    Conrado Javier Hace un mes

    My Little Ponilla.

  • luke towner
    luke towner Hace un mes

    This guy reminds me of Paul Gilbert.

  • Derrick Bonsell
    Derrick Bonsell Hace un mes

    People always forget the poor Tapir.

  • HenryManson
    HenryManson Hace un mes

    someone had to say it:
    Life finds a way!ídeo.html

  • Bold - Spirit
    Bold - Spirit Hace un mes

    that's mean it is possible to find unecorn.

  • Deepmalya Chakraborty
    Deepmalya Chakraborty Hace un mes

    Sir the reason they probably got bigger acc to me is because of gymnosperms like sequoia trees which were demandind that kind of height to exploit their leaves.
    When angiosperms came and almost wiped out the giagantic trees the larger dinos were starved to death.
    I think if angiosperms were toxic to dinos as presently vegetarian reptiles are still very very rare.

  • Nick de windt
    Nick de windt Hace un mes

    A video on the development of dinoflagellates would be pretty cool

  • Nw wing
    Nw wing Hace un mes


  • Nabil Zeghli
    Nabil Zeghli Hace un mes

    why they didnt interbreed with each other ?!

  • Gemma Prefumo
    Gemma Prefumo Hace un mes

    On the same note as niche mammals, it would be so interesting to hear about Australian megafauna!

  • SomeoneCommenting
    SomeoneCommenting Hace un mes

    If there were two different things to eat, one group simply evolved to fill the niche of eating the other stuff that the main group was not eating. Simple strategy to take advantage of resources and diminish having to compete for the same food in hard times. That's why pandas ended up eating bamboo. Nobody else was eating that junk.

  • Kat The Nerdfighter
    Kat The Nerdfighter Hace un mes

    I did not know how closely related rhinos and horses were. Huh.

  • Carl Kaufman
    Carl Kaufman Hace un mes

    But wouldn't the 2 different groups not diverge unless the longer necked ones bred with other longer necked ones and the same for the others? Why would that happen?

  • Tap Gaming
    Tap Gaming Hace un mes

    How the chalichothere split in half

  • Jerri Kangasniemi
    Jerri Kangasniemi Hace un mes

    Video just started; Am I hearing Hank Green?? OMFG RANDOM HAPPINESS

  • Aunty Googol
    Aunty Googol Hace un mes

    Maybe they became horses.

  • Tyronicus Vids
    Tyronicus Vids Hace un mes

    I think the dome is for storing nutrients or fats kinda like a camel

    • Hunter Smith
      Hunter Smith Hace un mes

      Tyronicus Vids a bony dome wouldn’t likely be good for that.

  • Eric Maldonado
    Eric Maldonado Hace un mes

    Could this be the a similar path humanity might take in the near future? Seeing as different groups of people attract similar groups of people. Seeing alot of incredibly fit, hard physical working people seek each other out, and very intelligent people seek out other intelligent people. Just like in "The Time Machine"

  • Dylan Geltzeiler
    Dylan Geltzeiler Hace un mes

    5:25 I have seen this Illustration in some Dinosaur Book. Right at the few pages of the Age of Mammals from almost the last 3rd of the Book. Mmm, what was the name of that Book again? Oh! "Eyes On Nature: Dinosaurs."


    Imagine if we were riding rhinos instead of horses 😂

    ALAM_ ILMUKU Hace un mes

    Pleace subtitel indonesia

  • Frost Dragon King
    Frost Dragon King Hace un mes


  • Melissa
    Melissa Hace un mes

    Do a video on Therezinosaurus please!!! (:

  • SphereSquared
    SphereSquared Hace un mes

    I always wonder how a animal worked or looked between while evolving into a state. Like the four chambered digestive system, I understand it makes sense that they evolved into that, but how did their digestive system work along the way? For lack of knowledge or imagination I always imagine it to be an imperfect system for a while. But that doesn’t make sense because it would be a disadvantage..

  • Jan Kapera
    Jan Kapera Hace un mes

    ...because they were two different species? doh. Theory of evolution remains only a theory.

    • Jan Kapera
      Jan Kapera Hace un mes

      Why someone find bones burred (violently) in ground and say: evolution? I don't know why. Fossil bone is a fossil bone - nothing more.

    • Hunter Smith
      Hunter Smith Hace un mes +1

      Jan Kapera Why though? Why is mass attracted to other mass?

    • Jan Kapera
      Jan Kapera Hace un mes

      Ok. How to check theory of gravity? just trow a rock. And i can measure it. How to check theory of evolution? Waiting 1 million years? :D Its impossible - no one can live for so long ;) Big difference here...

    • Hunter Smith
      Hunter Smith Hace un mes +1

      Jan Kapera Just like the theory of gravity. Science uses ‘theory’ differently then mainstream society.

  • zam rose
    zam rose Hace un mes +1

    Imagine getting punched by those animals

  • Daniel Ocampo Daza
    Daniel Ocampo Daza Hace un mes

    Say chalicothere again, I dare you.

  • OneMaleHuman
    OneMaleHuman Hace un mes

    As your main statement in answering the question, "How did they split in two?" You said both sets of traits existed because they were both useful in their own way and "slowly, over time" they drifted apart. These sentences do not seem to answer the question of why they would not continuously blend with their own kind, eventually causing a single set of useful characteristics. They're eating the same food, unlike my understanding of the cause of separation of Galapagos finches. Basically, I don't think you said the answer to the title of the video. Maybe the actual reason is more like a genetic theoretical math solution, which you did not include in the video?

  • sharkfinbite
    sharkfinbite Hace un mes

    4 chambered=v4 engine. haha

  • sharkfinbite
    sharkfinbite Hace un mes

    Knuckle walker

  • Geoffrey Lee
    Geoffrey Lee Hace un mes

    Could they cross breed?

  • Vennom Scandi
    Vennom Scandi Hace un mes

    bipedal equines wouldve been really cool

  • Steve W
    Steve W Hace un mes

    Horses with claws!?!

  • Andre Vieira
    Andre Vieira Hace un mes

    Nice blazer

  • Lol Go1
    Lol Go1 Hace un mes

    yo where my boy yutharanus at

  • Loudmouth Reviews
    Loudmouth Reviews Hace un mes +3

    Such an odd looking animal so different than anything alive today. Fascinating

  • جيري ساينفيلد

    Please make a video about the Evolution of both of Tyrannosaurs and Ceratopsain Dinosaurs

  • JackCain
    JackCain Hace un mes

    Please do an episode on the evolution of Bats!

  • Ric C del P
    Ric C del P Hace un mes

    Please do a video on the first parasites and how parasites evolved !

  • Plipp the First
    Plipp the First Hace un mes

    I want to know more about lakes. Just give me anything about lakes. I know next to nothing and it’s embarrassing.

  • Rebel Ivy
    Rebel Ivy Hace un mes

    Would it be kinda the same thing for giant sloth which split in anteaters and sloths?

  • Deathbrewer
    Deathbrewer Hace un mes

    The bony dome reminded me of a mythical "unicorn" that didn't quite develop all the way, lol.

  • A
    A Hace un mes

    rip these weird homies

  • k98killer
    k98killer Hace un mes

    Do the evolutionary history of the unicorn next.

  • culwin
    culwin Hace un mes

    I remember this expansion

  • Hei Chan
    Hei Chan Hace un mes


  • Robin Chesterfield
    Robin Chesterfield Hace un mes

    This has nothing to do with the actual science, but: That painting of the mama chalicothere showing the baby how to browse is freakin' adorable. :)

  • Hannah and Hugh
    Hannah and Hugh Hace un mes

    Is there much evidence in the fossil record of extreme weather events?
    What was the worst known storm in history? Or the largest known tsunami?
    Or is there only evidence for long periods which involved more extreme weather?

  • Jack Arthur
    Jack Arthur Hace un mes

    to what extent can we call a bird a reptile?!?!?! I cant find that answer anywhere! I know they're descended from reptiles but birds are still classified in the class Reptilia , so would it be corret to call a bird a reptile?

    • Afif Brian
      Afif Brian Hace un mes

      yes, but it doesn't matter if birds are reptile or not, it just semantics

    • Jack Arthur
      Jack Arthur Hace un mes

      I know about cladistics and paraphyletic grouping, but I read an article on a website run by the University of Michigan that called birds reptiles. I haven't actually seen a credible article that said that birds were not reptiles, and some of them (like the one mentioned before) talked about birds as unusual reptiles.

    • Afif Brian
      Afif Brian Hace un mes

      read about cladistics, reptile is called paraphyletic group, it means that not all their descendant can be called reptile, like mammal and bird.
      Just like all vertebrate are descendant of fish, but we're not fish

  • reluctantlydancing
    reluctantlydancing Hace un mes +1

    Id like to know: warm blooded vs cold blooded. Which came first( i assume cold blooded?) Has it only evolved once? What was the first warm blooded animal?

    • Hunter Smith
      Hunter Smith Hace un mes +1

      Cold bloodedness came first. Warm bloodedness, as the other guy stated, evolved at least twice. I don’t think we know for sure which was the first creature to be warm blooded.

    • Abahrelghazali
      Abahrelghazali Hace un mes +2

      Hey, I can answer that! Warm bloodedness evolved at least twice - once in mammals and once in dinosaurs (including birds). Maybe more than that.

  • R. J. Amado
    R. J. Amado Hace un mes that SciShow's Hank Green??? Waits for end credits. It is!!!!

  • wcdeich4
    wcdeich4 Hace un mes

    If they evolved in the same location, why didn't they cross breed producing only 1 species w/ both long arms & long necks?

  • AlexdoesSwag
    AlexdoesSwag Hace un mes

    So.... they were pre-unicorns?

  • Jason Thornton
    Jason Thornton Hace un mes

    so horses are an ancestor of theirs, and your last line is "some things evolution can't get you out of" um these two facts seem incongruous

  • The All Seeing Eye
    The All Seeing Eye Hace un mes

    Calicotherium skipped leg day ?

  • MLaak86
    MLaak86 Hace un mes +1

    Specialisation carries a huge risk given the constantly changing nature of earth.

  • waffleless
    waffleless Hace un mes

    I want to ride a Chalicothere.

  • postshift19
    postshift19 Hace un mes

    But if they lived in the same place at the same time, why didn't they interbreed, thus preventing them from becoming two different animals?

  • theicedragon248
    theicedragon248 Hace un mes

    I'd love to see an episode on red algae, and the first plant life on earth!

  • Sven Sedric
    Sven Sedric Hace un mes

    I'd love a video about clarifying who was the biggest land mammal out of Paraceratherium, Palaeoloxodon namadicus or Mammuthus trogontherii

  • David King
    David King Hace un mes

    sorry not convinced. If the long necked and long limbed types were living together then there would have to be some form of sexual selection going on. Long necked preferentially mating with long necked etc otherwise the characteristics would average out and differences dissapear rather than being amplified.

  • Petra44YT Nein!
    Petra44YT Nein! Hace un mes

    Just imagine, you wake up somewhere with a couple of these critters around. And you know that a time machine has sent you millions of years into the past, and you'll have to outlive your life there, and you'll never speak to another human being again.

  • HanyouxFromxHell
    HanyouxFromxHell Hace un mes

    okay, related to equines but *did not* turn into horses. gotcha.

  • John Hightower
    John Hightower Hace un mes

    Aww... evolution really takes no prisoners.

  • Poramut Thamprechavai
    Poramut Thamprechavai Hace un mes

    I'm a paleontology enthusiast and know Chalicothere since I was child but I didn't know before that they split to two subgroups due to parallel evolution! Thanks Eons!

  • Senefen
    Senefen Hace un mes

    Hey! I'd love to see some videos on the extinct Australian megafauna. Most people don't even know they existed and there were some really interesting creatures.

  • Apex
    Apex Hace un mes

    do about the evolution of seals and walrusses

  • Om King
    Om King Hace un mes

    Great information. Thanks for update.

  • Omar Omokhodion
    Omar Omokhodion Hace un mes

    Who was the first animal to taste and enjoy the sanguinity of blood?
    Of rugged steel his savage soul was made.

  • Rogelio Victoria
    Rogelio Victoria Hace un mes

    How many times can you say Chalicothere?

  • RowenBarbary
    RowenBarbary Hace un mes

    If you don't mind my saying, I think the study of evolution has progressed beyond the main point in this video. This still holds to the textbook story of how the giraffe got it's next. Natural selection is more complicated than that. I highly recommend reading up on the theory of punctuated equilibrium. Gradualistic evolutionary change is very limited. There are plenty of Steven Jay Gould essays that can explain this more deeply.

  • camo jorel
    camo jorel Hace un mes

    Show idea?
    Marsupials and mammals both shared many traits...
    What if marsupials evolved their own "humans".
    Bi pedal marsupial humanoids that learned to control fire too...
    Nevermind, this is getting too LOTR, somebody'll probably make a tin foil conspiracy religion out of this... lol

  • Peter Houle
    Peter Houle Hace un mes

    ha, "as you do"

  • Chimera
    Chimera Hace un mes

    Hank! You are the best!

  • Me and I
    Me and I Hace un mes

    Schizerotherinae? Doesn't that mean something like...split animal? If so, that sort of makes sense.

  • ed denz
    ed denz Hace un mes

    Thx beauty of evolutionary theory is .....
    No words

  • Omar Dominguez
    Omar Dominguez Hace un mes

    Let me get this straight,
    Our Earth had the same EXACT geographical mapping 55 million years ago???

  • Gabriel
    Gabriel Hace un mes

    Amazing video again. But i would argue this is not exactly parallel evolution: parallel evolution is the development of similar traits in distinct species. The way you tell it the traits were already present in the ancestral species and developed further in the diverging species. That does not sound like textbook parallel evolution to me. But maybe I am nitpicking here. I really love the videos you guys make, even as a biologist I learn a lot every video.

    • Abahrelghazali
      Abahrelghazali Hace un mes

      It's not nitpicking if its a main point of their video! Thanks for the correction :)
      (And as a fellow biologist, this also annoyed me. Still learn a lot every video as you say!)

  • William Clore IV
    William Clore IV Hace un mes

    Hey, was wondering if you guys could do a video on the tendency of paleoartists to shrink wrap fossils? Like how you see pictures of dinosaurs with jutting bony parts or all lithe and skinny? Unless you guys already have... Sorry, just found this channel recently tho I've been watching a bunch of the videos.But love the content you guys make! :)

  • Jc Deleon
    Jc Deleon Hace un mes

    Which animal had the first umbilical cord?