How the Chalicothere Split In Two
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- Опубліковано 23 кві 2018
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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 / alphynix and nixillustration.com
And thanks as always to Nobumichi Tamura for allowing us to use his wonderful paleoart: spinops.blogspot.com/
Finally, thanks to Dmitry Bogdanov, Roman Uchytel, Ryan Somma and Julio Lacerda for their excellent images as well.
Produced for PBS Digital Studios.
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References:
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. - Наука та технологія
It's always so fun to see the weird and "funky" body plans that eventually went extinct.
its also kind of sad, I wish they were still around
They are, through horses and rhinos. I know what you mean though.
Meh, they lasted for a long time. I wouldn't call them weird and funky if anything they were the norm. We are the weird and funky offshoots.
We humans love to pound our chests and proclaim ourselves the Pinnacle of evolution but the truth is we haven't been around very long at all. There are designs out there that have our highly lauded "intelligence" beat by tens of millions of years.
In fact I wouldn't be surprised to find out our intelligence becomes an evolutionary dead end when we invent something that inevitably wipes us out like a sterilization plague, nuclear war or AI or some other sci fi apocalypse.
Also explains why we haven't found any smart aliens yet, their evolutionary tracts determined intelligence was a bad idea long ago.
@@josephmatthews7698
Name just one. Humans have dominated earth.
We clone them
i wish we could go back in time and just send crews of national geographic to capture film and create documentaries of extinct species
The closest thing we have then is CGI (and somehow accurate models).
Agreed
Hey you can't change anything in the past if it affects you. You wouldn't be born so time fix's itself
The closest thing we’ll get is the walking with trilogy
@@Lumberjack_king Have you ever read the short story, "A Sound of Thunder," by Ray Bradbury, about the effects of time-travel? It's not always obvious what will change the future.
As somebody who is very interested in the origins of Earth and species, this series is absolutely everything I've ever wanted, so thank you for that. I have a few questions that I've not seen tackled in any other documentaries. Where did viruses come from? Do we have any clue as to when they appeared? Obviously you can't find fossils of them. Any ideas as to what causes them to pop up? Should we consider them alive or dead? Thanks again.
Fox Anders +
ua-cam.com/video/UmH5vUpufyA/v-deo.html
Fox Anders I LOVE the story of earth's different epochs and the worlds created over deep time...LOVE this channel...what I wouldn't give to be able to go back and experience those worlds....I starve for information..lol...the three things I can never get enough of..the evolutions of the universe...the earth...life on earth...I found your comment very interesting....hope your curiosity is satiated. :)
Fox Anders yeeee! My boi from the shark tank going in for the silicon ! 408 ESSJ
Fox Anders Well fancy seeing a sharks fan here
4:37 Domed, crested or even horned animals, besides displaying towards others were useful to getting around the forest. They worked like a helmet or to move objects out of the way, such as branches, leaves, and the like. The cassowary is a great example.
10/10 Didnt know this but makes sense. Love seeing additional info in the comments!
*splits*
"See you later Rhino"
"See you later Horse"
"Hey it was a long time, i can run faster"
"Nice, i evolved a horn to protect myself against other mammals"
Zebra: "hElLo''
Horse: ''who are you"
Zebra: "I'm your cousin"
Horse: "ah the striped extra agressive donkey"
Rhino: "I don't remember have ng a cousing with stripes"
Rhino: well the horn doesn't work, bunch of monkeys with exploding sticks are making us go extinct
I had no idea until just now, that horses and rhinos were related. Thanks for sharing!
All living things are related, just to varying degrees.
A mammal and another mammal are more closely related than a mammal and a reptile for example.
So horses and rhinos are closely related because they share a recent common ancestor, but humans are also related to rhinos and horses, but our common ancestor is a lot further back in time.
a crocodile is more closely related to a pigeon than it is a komodo dragon
and tapirs! I bet a family reunion would be weird to say the least!
I think hippos and whales are also related! THAT'S A WEIRD THANKSGIVING GET TOGETHER!
@@Jakeassimilate I think he means on the same branch in taxonomy. Like all birds get a section of a tree branch, all bugs get their branch. Yes all living things are related in the big picture, but for most of us, "related" means a common ancestor that we all recognize, hopefully one that is still around
Could you cover the evolution of blood?
Do you mean the evolution of a circulatory system? Or an evolution of hemoglobin or red blood cells in particular?
This one is kinda interesting
water bear um, care to expand on that "no"? If you mean neither of those, then you mean the evolution of an interstitial fluid in general? Beginning with the first multicellular organisms?
Or this could be the evolution of cold/warm blood. So many good options here.
Why not both?
Please make a video about the evolution of Ratita(flightless birds). 307 people supported this request by giving their like to my comment last video. People are interested, I will insist until the end
João Pedro Yes!
Wow 307!? Of the 100s of thousands that watched that last video das amazing
Tasty Treats Actually, although the 307 are a small percentage, they ARE a percentage. I will represent them while I can. I am not saying "Hey my comment got famous", I am showing that people have interest in the subject and they deserve attention
YES
João Pedro I thought you were talking about a Pokémon at first!
when i watch videos about highly specialised animals i sometimes realise how extraordinarily adaptive humans are.
Other species must rely on evolution just to slowly adapt to new conditions or die out, while we are capable of adapting in a fraction of our lifetime to almost anything and can live nearly everywhere around the globe, even without our advanced technology . gives me a little sciencegasm
One of our tricks is that we cook our food. Removes toxins and makes practically everything edible. No other animal can do that!
Then again we might just be clever enough to create our own extinction event.
I think it's important to stress something you mentioned in passing in the video, the idea that evolution doesn't mean "progressively better", it simply means better-fit for a particular environment. The Chalicotheres adapted in two different ways to the same environment, but when their environment changed too much, or they faced too much competition in their environment, they were no longer better-fit and were unable to successfully adapt to the changes.
Wait. A non primate knuckle walker? I didn’t know they existed 😳 Retractable claws? 😳 Horse cats?
Can you go over trilobite evolution in an episode?
We did that! I was one of our first. (BdeP)
ua-cam.com/video/Aji2VnQFUCs/v-deo.html
Steven Baumann horse cat gorilla tapir?
PBS Eons excellent! I don’t remember it. I may have forgotten. Old age and all.
Are sloths related to calicopheres (sorry for the name butchering)
There are some non primate knuckle walkers that still exist today - anteaters.
There must have been a reproductive isolating mechanism to block gene flow to allow them to evolve in parallel. If the dome heads were used for mating displays, it might suggest that changes in mating behavior is what started the split. Interesting stuff.
These are my favorite prehistoric mammals. They're so unique!
I think there is a lot more to these strange looking creatures. They look like they were put together by a committee.
i don't think they're that unique tbh. I could see those types of animals living today, and they kinda still do. Just look at Giraffes and Tapirs.
But their hoofs didn't become claws, and they didn't walk around like a deer was forced into a gorilla mold.
Moose are built like that.
"Unique" is not a continuum so "so unique" doesn't make sense. "Unique" is binary; something stands alone and thus is unique, or it's not. But your usage is becoming more common. Who knows, but we might be seeing word evolution :)
“Long neck dome headed” go easy on them damn
If Chalicothere continued to evolve, it would end up walking around on two legs, eating salad from trees
EONS is so awesome!
Glad I found this channel. Nature is one of my interest
Game Head hi. I'm also fellow human. Definitely not computer. I have many life interest
if you like this you will love Scishow. there is also Scishow Space and Scishow Psych (:
ya and BBC Earth
Game Head me too
Same :)
“ Long necked horse like dome head things” Best description ever. Lol!
What's wrong with Dome-headed Long-necked horse like things ?
I loved this video! No one seems to talk about the ancestors of equines all that much, so this was pretty interesting, along with learning about the pros and cons of specialization through evolutionary history. I think some videos I'd love to see you guys do in the future would be more videos on primate evolution, since we have such an interesting branch on the tree of life. Learning about ancient lemurs, when monkeys and apes became a thing and how humans came to be the most successful primate of all time would be super interesting.
I love how they always give this take away lesson after every video. Continue doing your thing PBS Eons!
Can you talk about our evolution, the bizarre Deinocheirus, tyrannosaur integument and why therizinosaurs become plant eaters?
On therizinosaurs: New studies are finding that coelosaurs were ancestrally omnivorous, and that hypercarnivores like velociraptor and tyrannosaurus were the exceptions. From there I would imagine they took a similar path to the chalicotheres, evolving traits from both groups like claws and long necks.
OUR ☭
I would like to see something on hummingbird evolution. I know they're specialized, but from where did their brilliant colours, their abilities to fly upside down, backwards, etc, and their other abilities come? What did their ancestors look like? Thanks so much for all of the great videos!!
Great episode! This is a lovely example of evolution that we don't hear about often. Thanks, PBS Eons.
Do an episode on elephant evolution (including mastodons and mammoths)!
Fun fact: Get a Chalicotherium drunk on home brew and it'll love you forever, so much so that it will fling its poo at people you don't like on command.
Pbs is so underrated. You can learn so much.
I love this channel. I didn't get to learn this stuff in school growing up so I'm so happy this channel exists to help me learn. Beautifully done, everyone. Keep up the great work.
I swear every episode on this channel I watch I didn't know I was interested until I started watching. Learning about animals and stuff is always enjoyable.
thanks to you I now have an idea what parallel evolution is!
I knew nothing about these animals. Thanks for the video.
I've always found Chalicothere's fascinating, so thank you so much for making this video! I learnt so much from it.
Please do a video on the hypothesis of proto-pterosaurs!
Not sure if it's too contemporary for PBS Eons but I'd love an episode on the megafauna that humanity encountered as it spread out of Africa and into the Americas and how our ancestors interacted with them. There were wooly rhinos and mammoths in the North, armadillos the size of a car and Sloths the size of a bus in the Americas. In New Zealand there were Haast Eagles with 9 foot wingspans preying on 10 foot tall Moa birds as late as the year 1300. It's so cool to think that people just like us were once hunting, and even being hunted by these kinds of giants.
Id love to see this episode!
I'd love to see something about the common ancestor of vertebrades and arthropods! :D
Worms, it's always worms
I know... but what KIND of worms, what made them SPLIT, what was the conditions it lived in... etc.
Enthused Norseman +
Seeing as vertebrates and arthropods are on opposite branches of the bilaterian tree of life the last common ancestor was probably back in the early Ediacaran as the major clades of protostomes (the group including annelids arthropods mollusks nematodes etc) and deuterostomes(echinoderms, chordates etc.), had to have at least diverged by 555 million years ago. Summarizing the techno-jargon of several papers the last common ancestor was most likely a microscopic "worm" that lived in ocean sediment "swimming" between sediment grains. when the split occurred seems up for debate but it probably happened at least 600+ million years ago if techniques to trace back genetically when organisms diverted are accurate.
The last common group of these organisms is called Nephrozoa so it would probably be something like a Nephrozoan worm?
I would recomend looking for david Attenborough and the age of vertebrates
This was a great video on parallel evolution, definitely going to recommend it.
Ilove this channel, so informative and at the same time fun to watch.
Whoa! I learned something new again! All the creatures I know now are spectacular! Thanks EONS!
Love this channel
thank you for all these interesting videos, i dreamt so much about this kind of documentaries !
These are really good videos. Great balance of accessibility and information, if only the videos were longer
Anyone who has played ARK knows the terror of chalicotheriums
I love these underrated anmals, thank you for covering them Hank.
I always show your videos to my school students . They are really helpful
So cool to see something on these fascinating animals at last!
If they survived longer, they could have gave rise to a species of humanoid horses, like Bojac.
One of the best parts of these videos is going into the comments and reading about the things people are suggesting for future videos.
Sympatric speciation at work!
Excellent video!
Nice video, penguin evolution could be interesting next ;)
Little known fact: Chalicotherium was great at throwing boulders at enemy tribes. It also really likes beer.
I like beer . . .
David Squires ✌️Ark✌️
Liar liar
Lol ark
Yep and those beer barrels are way too expensive...
Great presentation
Another great video!
But what stops them from cross breeding?
Two main factors:
Firstly, animals tend to mate with animals that look similar to them. The ones who were willing to mate with radically differently looking animals probably mated outside their species and produced no offspring.
Secondly, long necks and long arms were helpful. However, if they interbred the offspring may have had just medium sized necks and arms, meaning they were less likely to survive.
no tindr
Upcycle Electronics There had to be some period of separation between two populations that allowed enough divergence to prevent later mating or fertile hybridization.
This difference may not have been something that fossilized. For example, the human lineage experienced a merger of two distinct chromosomes present in our shared primate relatives.
en.m.wikipedia.org/wiki/Chromosome_2#Evolution
A chromosomal change of this type would likely make subsequent hybridization extremely unlikely, even before any outward differences got in the way.
+larthallor, not necessarily, speciation can occur when two different extremes of a trait: (long neck, short front legs vs short neck, long arms) are winning body plans but intermediate traits (medium neck, medium arms) do not work as well. Over time there will be more on either end of the spectrum and less in the middle until they're different species.
@@kellydees1938 mules are absolutely not exclusively female I happen to ride a male one. Fertile mules are a great rarity but they do exist Those are exclusively female
Maybe the dome was used to knock down trees to get at those high leaves?
I don't think they would've needed the long necks then, but similar animals like ground sloths knocked down trees.
The one's with the domed heads were the ones who didn't develop the longer more flexible necks; seems to me they'd need shorter, sturdier ones to support the pressure of using it to bend/knock over trees to get at the leaves. The shorter legs would also keep their center of gravity lower to give them a sturdier base.
Pretty sure the dome was for professional sports.
I had thought this as well.
dude what?
That moment at the end was genuine gold
Great information. Thanks for update.
If Rhinos and Horses are related, this so means the Unicorn was their cousin
Alex Rossouw actually the word unicorn used to refer to rhinos until fairly tales corrupted the world.
Neptune where did that came from?
Out of Uranus.
Elasmotherium.
Ayush Sharma but rhinos have two horns?
Question- isn't the process of one species evolving into two different ones called divergent evolution, not parallel evolution?
coryman125 Divergent evolution is where members of the same species evolve to suit different lifestyles or habitats ..Darwins finches for instance..same critter. Different adaptation for different niche. Parallel evolution. As here. Is where different methods are evolved to exploit the same niche. At least that is what I understand by the terms 🙂
That would make sense actually. I thought parallel evolution was two different species evolving in similar ways- for example, a species diverges into two different species with, say, differently shaped feet, but the two species end up evolving similar mouths.
I'm not great with biology though (truth be told, I'm more into chem and physics) so I could be wrong
coryman125 when two species from different branches accumulate similar adaptations it is called convergent evolution.
Divergent evolution is when a single species evolves into many other species because they have to adapt and survive into the new environment they have moved into. Parallel evolution is when a single species, in a single habitat with unchanging conditions manage to evolve differently.
I asked the author of this script, paleontologist Dr. Meaghan Wetherell, and she points out that divergent evolution and parallel evolution are easily confused. She says:
"Parallel and divergent evolution both define groups that start out closely related. Divergent evolution leads to two different ecologies and morphologies; parallel leads to similar ecologies and morphologies.
Chalicotheres diverged in their morphology, but remained parallel in ecology. They are doing the exact same thing, and both groups are evolving morphologies to become better at doing that one thing - this is parallel evolution.
At the same time, the things they’re doing are different structures, so you could also argue that lengthening a neck versus lengthening a forearm is divergent. But since both things are for height, and the height is for the same reason (high browsing), parallel is a better term in this case.
Divergent evolution tends to be described as species changing traits to adapt to different niches - here, their niche is the same, they’re just accomplishing it in slightly different manners."
Hope this helps! (BdeP)
This channel is great!
I could watch 100 more videos on this type of evolution. So fascinating. 👍
I’m so excited about these animals and also supremely disappointed I’ve never heard of them previously
Could you make a video on viruses in the history of evolution?
Excellent!!! Especially noting the adaptations of some claws being retractable.
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!
Why didn't both groups not mix before they became two species? I mean I understand if they lived at different places, but at the same place but did not mix? Doesn't make any sense to me.
Why didn't the different types continue to mate and blend their genes?
This is the third comment I've copy-pasted this on, but this is a pretty big question the video never addressed: Animals tend to choose mates that look somewhat similar to them morphologically, it's mainly a species recognition thing. The moose that tried to mate with the deer didn't have any offspring, you know?
Christian Schiller I suppose that is one possible explanation.
I had a thought after commenting. What do you think?
Perhaps the combined genetics simply were not as strong as the separate distinct genetics. And thus the animals who combined did not last long enough to leave much of a fossil record.
Perhaps something about the combination of long neck and bump on head is not as useful as the genetics separately. Terrible example, but the point remains.
I've heard evolution explained as a species climbing a mountain, where each upward step is a favorable adaptation. What you are suggesting is that the "mountain" "splits" toward two separate peaks. You might call this a saddle point. I would expect such splits to be rare compared to all the other points in the mountain. And even if they weren't I would not expect the gene pool to split. It's not like the members of the species could know not to breed together.
Edit: After watching again I think there may have been separation at the beginning of the split. This isn't explained, and the title is a little misleading. In that case it'd be like the two chalicothere strains took separate uphill paths. Which sounds reasonable.
One identifier of "species" is the inability to have offspring, or viable offspring. For instance, a cat and a dog cannot interbreed. Different dog breeds can since they are really just varieties of the same species. A horse and a donkey can produce a mule offspring, yet it is sterile, so donkeys and horses are different species.
The different pterosaurs were all different species, so they could not interbreed.
Awesome video !
Im assembling an Ikea forniture and listening to these videos at the same time.
Great experience.
please make a video about significances of the teeth in paleontology or about evolution of teeth...
For those of you who don't know teeth are extremely useful in paleontology.
First of all, they're the hardest parts of an animal, so it's not uncommon for them to be the only parts to fossilize.
Second of all, the teeth can tell us a lot about the animal's daily life. The diet is one of the biggest, if not the biggest, factor in how animals evolve, and looking at them can tell us if the animal ate leaves, grass, larger animals, smaller animals, fish, and plenty of other unique diets.
thanks Christian
It's my pleasure, I love helping out people who want to learn more about how the world works.
I'm here cause of the game ark survival 😅
Favorite tame by far, but I always called pronounced it like
kal ic O th or e um
Beautiful!
my addiction to eons is stronger than any addiction known to mankind! keep up the great work !!!
How did complete insect metamorphosis come about? It doesn't quite make sense to me how a sequence of larva -> pupa -> adult would arise in the first place, much less how its initial development be beneficial to insects of any era. In particular, I am considering the development of ant and butterfly species, but I'm aware many, many (many) other species undergo pupation. Thanks for reading!
You can put it under one of the many strange permutations that ended up working. Evolution is not a person, and it does not choose what makes sense and what doesn't, organisms develop in all kinds of odd directions and those that can survive keep on living and evolving in their direction.
My theory: unicorns
Maggie Kollar but where is the pegasus :(
water bear i think he means a kind of chalicothere is a unicorn....I don’t understand it either
Maggie Kollar unicorns are not real
Unicorns leaked in from an alternate timeline where calicotheres never differentiated
I like the bony dome. Looks like a crown fit for a king.
Fascinating evolution.
I am surprised that there was no reference to wolverine when "retracting claws was mentioned."
Migrated here from TierZoo :)
James Bernadette
Yep
James Bernadette Same dude
nice
I might be bad at remembering names and terms, but it's rare to watch one of these that I know nothing about. Good job.
Thank you for using the correct terminology . Me being an educated person in the feild of nature i appreciate the attention to detail and pronunciation of the terms... Many, and i mean many other youtube channels claiming to be showing accurate nature content are pethetic .. From a nature guid and conservationist . I thank you
do therizinosaurus
Clawed gorrila horses.
Why haven't I seen these magnificent creatures in a fantasy novel series yet?
Omg i love you guys. So great.
Ayy, finally a video about one of my favorite extinct mammal groups
but why did they seperate into two species? like, if they could interbreed, why did they diverge so much? in the examples of evolution from school there is always a geographical thing which splits the population, but this video fails to offer an explanation for why this was not nessecary here, and i am having a confuse.
Animals tend to choose mates that look somewhat similar to them anatomy wise, I think it's a species recognition thing. The moose that tried to mate with the deer didn't have any offspring, you know?
Yep, this. Wolves and coyotes can mate but rarely do. It's a matter of taste.
I also find this confusing. Without something to prevent interbreeding I'd expect them to drift toward a longer necked longer forearmed animal. You can't just say, well they looked somewhat different, because evolution is so gradual that normal interbreeding prevents significant differences within the gene pool. Before any major differences happen something usually has to split the gene pool
Stephen Johns well it did happen fairly early on in their evolution and I’m going to guess that all the later species of chalicotheres didn’t come from one ancestral form so this basically meant that no interbreeding would occur because the two ancestors were to separate species already
So you're suggesting they were separated at the beginning of the split. That makes sense given the wide geographical distribution, but this was not mentioned in the video. The video title is also misleading. This is more an explanation of why they continued to diverge
I didn't know that cows are "artiodactyls."
But seriously, your explanation why they split into two different species doesn't really add up. If they all lived on the same continent with easy access to each other, interbreeding would have prevented creation of new species. There's something more to it. (A good example is when a single species of animals is separated on an island, or on different land-masses, etc. which over time creates new species.)
Speciation doesn't just require a physical barrier. That's a form of speciation called Allopatric speciation. There is also peripatric and parapatric speciation (like what is happening with polar bears - no geographic barrier, but animals on the outskirts become different) or sympatric speciation (organisms spontaneously become unable to breed without a barrier - this happened with genome reduction multiple times in Muntjaks, for example). Also, physical isolation does not have to be an entire continent difference, it can be a mountain barrier we don't have evidence for in the fossil record, etc.
Thanks. You make a good point.
Wow! That's so cool! Life never ceases to amaze me!
I really like these episodes about weird animals.
Ouch. He used the words "different kinds". Creationists everywhere collectively said, "Ah ha!"
Only here to see how you pronounce chalicothere
Can we have more of these videos more often ?! Love what you guys are doing!!
I love your channel.
I love these things in Ark
jasminhook96 I thought they were gonna mention Paraceratherium because they have similar genus names
Ah, Indrocotheres.
You are describing divergent evolution, not parallel evolution. Parallel would be two related animals, separated by distance, evolving similar adaptations to deal with similar niches.
divergent evolution exploit different niche, parallel evolution deal with similar niche, this video is right
Steve O'Brien what you are talking about is called convergent evolution.
Let's go to Wikipedia. Parallel evolution is the development of a similar trait in related, but distinct, species descending from the same ancestor, but from different clades.[1][2]
en.wikipedia.org/wiki/Parallel_evolution
What's the similar trait here? They started off from the same ancestor or related ancestors, then *diverged.*
Steve O'Brien
"Convergent evolution is where two different species adapt to the same or similar ecological niches. ", "Parallel evolution is where a population diverges, yet they continue to evolve similarly."
~ _S. B. Carroll, Evolutionary biologist in his book Endless forms most beautiful._
In my opinion the definition of parrellel evolution they used is consistent with this one...
The use of the term parallel evolution in this video is inconsistent with the general biological usage of the term, which refers to INDEPENDENT acquisition of traits that were absent in the last common ancestor. Depending on who you ask, the difference between parallel evolution and convergent evolution is either that parallel evolution uses the same developmental pathways while convergent evolution uses different developmental pathways, parallel evolution involves closely related species while convergent evolution involves distantly related species, or they are interchangeable terms. See Arendt, J., Reznick, D., 2008. Convergence and parallelism reconsidered: what have we learned about the genetics of adaptation? Trends in Ecology & Evolution. 23, 26-32.
Fascinating!
I loved the video.
Could you guys do a video on ocean acidification, Earth's history with higher avidity oceans, and what species tend to do better than others?
...sorta like the different races of humans?
*covers head in defense*
you are correct. you are also correct to cover your head in defense. the pelting is coming i'm sure...
Nah, those developed in different areas, and maybe even through interbreeding with different " Human " species.
Physical differences between people were based on geographic separation unlike these animals. For instance, everyone with genetic roots mainly in sub-Saharan Africa has dark skin and hair (other than albinos), while everyone with genetic origins mainly in northern European is paler. The separate characteristics didn't develop within a single group living together. And with humans there aren't actually separate discrete groups. Instead, as you move from one region to another, the people you encounter in between gradually look less like those of the first region and more like those in the second.
to Nouvellecosse
you can also consider it parallel evolution if some of the differences in regional environmental qualities are considered insufficient to cause differentiation of that magnitude on its own. and/or if the groups often occupy the same regions OR regions that overlap or are in close proximity. all but the first detail are definitely true of most of the major ethnic groups of humans for most of recent history (before anyone says it, i used the word "most". there are exceptions here.). that said, the first detail is less close to being unilaterally correct. indeed, its not unilaterally correct. BUUUUUT, its correct at least a lot of the time as well. just not to the point of being nearly an "all statement" like the other details nearly are.
Different races of humans have mostly only evolved in different areas, and the differences are quite small, as we've only quite recently emerged from a very, very unusually tight genetic bottleneck as a species (we almost went extinct). They exist though, Tibetan lung capacity and Kalenjin (Kenyan tribe) running capabilities being two great examples, both possibly having some of their origin in breeding with earlier human species. Probably important to note right away that we've never proven any kind of superior/inferior cognitive abilities between any human races by force of genetics alone using modern, peer reviewed, reproducible science, but that doesn't mean there's no way it exists or that we'll never find any.
Fascinating, keep up the good work #PBSESONSISLOVE
One thing you might have mentioned in addition is that animals may tend to diversify into specialized niches more when there is greater competition ie a great abundance of animals may create greater evolutionary pressure to diversify. great presentation thank you
MORPUS are wonderful , wish they were still here . I saw the bones in a museum , they are so great