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Why No Giant Mammals?

Оценок: 29322 | Просмотров: 1829912
Hank gives a quick run-down of the reasons scientists think the land mammals of today are nowhere near the size of the largest sauropods. Some of them might surprise you! If you liked this video, check out more videos about natural history and paleontology on SciShow's sister channel, Eons: https://www.youtube.com/eons Like SciShow? Want to help support us, and also get things to put on your walls, cover your torso and hold your liquids? Check out our awesome products over at DFTBA Records: http://dftba.com/artist/52/SciShow -- Looking for SciShow elsewhere on the internet? Facebook: http://www.facebook.com/scishow Twitter: http://www.twitter.com/scishow Tumblr: http://scishow.tumblr.com SOURCES http://news.discovery.com/animals/how-dinosaurs-got-so-big-120131.html http://dinosaurs.about.com/od/dinosaurevolution/a/bigdinos.htm http://www.newscientist.com/article/dn19771-why-mammals-grew-big--and-then-stopped.html http://www.scientificamerican.com/article.cfm?id=land-size-limits-body-size http://ngm.nationalgeographic.com/ngm/0507/resources_who.html http://earthsky.org/earth/felisa-smith-why-mammals-havent-out-sized-biggest-dinosaurs http://www.sciencemag.org/content/330/6008/1216.abstract http://www.cam.ac.uk/research/features/mammals-vs-dinosaurs http://blogs.smithsonianmag.com/dinosaur/2012/06/when-mammals-ate-dinosaurs/ http://svpow.com/2013/02/19/personal-milestones-publishing-the-ph-d http://www.slate.com/articles/news_and_politics/explainer/2009/02/a_snake_the_size_of_a_plane.html http://www.dinodatabase.com/dinorcds.asp http://voices.yahoo.com/indricotherium-largest-land-mammal-ever-237482.html http://science.kqed.org/quest/2010/03/17/the-largest-land-mammal-that-ever-lived/ http://phenomena.nationalgeographic.com/2013/02/25/dinosaur-reproduction-not-ancient-gravity-made-sauropods-super-sized/ http://www.popsci.com/science/article/2012-02/hot-weather-makes-mammals-smaller-%E2%80%94%C2%A0what-does-mean-global-warming http://scienceline.ucsb.edu/getkey.php?key=427 http://www.smithsonianmag.com/science-nature/dinosaurs/How-to-Build-a-Giant-Dinosaur.html http://www.plosone.org/article/info:doi/10.1371/journal.pone.0028442 http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/bluewhale.htm
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Текстовые комментарии (3839)
B Z (4 дня назад)
Humans killed them and ate them.........never ignore the facts.
Osumanjin (7 дней назад)
1:50 so you say global warming was a good thing ?
Stephen Knizek (11 дней назад)
Why do I see more Hank Green on my YouTube than John?
William Jordan (11 дней назад)
And man would hunt them to extinction, which has happened.
Zach Dietrich (13 дней назад)
the North American Moose is currently experiencing a species crisis due to tick infestations. food for thought.
kris loist (25 дней назад)
2:15 Sounds like Steve Buscemi.
The JP (29 дней назад)
Bradley Thurmond (29 дней назад)
does this mean the universe is expanding?
President Togekiss (30 дней назад)
But why didnt birds grow back to being Utahraptor sized at least> I never undesrtood that.
Panzer Raven (1 месяц назад)
Ever heard of the Dutch? 😂
IamKingOfHearts (1 месяц назад)
Would that be possible in a very cold environment
alien collective (1 месяц назад)
yeah whales, giraffes, elephants, and sharks all no longer exist
maximaldinotrap (1 месяц назад)
Um there are land mammals the size of dinosaurs. We call them every mammal ever. Not all dinosaurs were massive and even Triceratops and Tyrannosaurus Rex were not much bigger than elephants in height. What you mean is none the size of sauropods.
LordOfThe Flightless (1 месяц назад)
Same reason less mammals fly. Bones aren't hollow, dinosaurs (Like birds) had highly efficient respiratory systems and various other adaptations for being big, the same adaptations that allow birds to fly so well and be pretty much the dominant aerial life forms on the planet. I mean bats are unlikely to outcompete birds in niches that birds fill. They may fill similar niches. But alot of hate are nocturnal, birds don't have echo location though. Good job bats.
Marko Jotic (1 месяц назад)
blue whales are the largest animal ever, the largest living thing is a mushroom https://www.scientificamerican.com/article/strange-but-true-largest-organism-is-fungus/
INKY DROPKICK (1 месяц назад)
That's one big tapir
and ? (1 месяц назад)
How have you forgotten that great and glorious mammal, native to the united states? THE LAND WHALE.
Steve Smith (10 дней назад)
Hey, we aren't the fattest country anymore. So please focus your attention on the middle east, specifically those oil rich nations
Nicko Maleitzke (1 месяц назад)
I think another reason is likely because of the huge number of humans that live in any given area. We do take up a lot of space for a species that is relatively small due to our large numbers.
Nocturnal Recluse (1 месяц назад)
Dinosaurs weren't reptiles, they were warm blooded like us.
Nocturnal Recluse (1 месяц назад)
We killed them all... unless you're only reffering towards terrestrial mammals?
Nahidh Kurdi (1 месяц назад)
But accordingly, would not that indricotherium cook it's flesh through?
Metal Rules (1 месяц назад)
Being big is a bad thing because if a mass extinction happens big animals are the first to die off.
Metal Rules (1 месяц назад)
Blue whales lol
samiamrg7 (1 месяц назад)
Another thing about metabolisms is that whatever the metabolism of Dinosaurs was like, they were probably slower than most mammals, meaning they required less nutrition than an equivalent sized mammal.
Andrew Jackson (1 месяц назад)
Erm elephants whales elk moose polar bears grizzly bears all as big or bigger than most Dino's, get ya bollocks correct.
yoxredwolf (1 месяц назад)
Humans woulda killed anything bigger than elephants.
Bruno Kooij (1 месяц назад)
Robert Wadlow is offended.
Kilgore Trout (1 месяц назад)
2:25 That's a pretty bad reason. Animals evolve their metabolism along with everything else, and mammals have all different metabolic demands and body temperatures depending on their size. If selective pressures would be favorable for large mammals to exist, their metabolisms would adapt accordingly.
Alex West (1 месяц назад)
Everytime the camera moves into homeboys face for a closeup I start to feel uncomforatable and tab over to reddit
Dan Man (1 месяц назад)
blah blah blah
Jacob Thorpe (1 месяц назад)
So, attack on titan?
Fishfan 2 (1 месяц назад)
Was that a paraceritherium in the thumbnail
dreful blig (1 месяц назад)
We ate them and brought them to war
yo niha (1 месяц назад)
evolution; filling niches; optimization of energy according to how an animal lives
wood1155 (1 месяц назад)
What ? That sauropod was 60 m long ? Are we sure about that ? How accurate can this be ? This can't be right I've never heard of any that wee longer than 45 m
Marshall Banana (1 месяц назад)
Oxygen content is way, way lower now than it used to be. A huge body is terribly expensive in oxygen.
RainbowGotGud (1 месяц назад)
Blue whale
aol.com (1 месяц назад)
If are ancestors manage those big game properly and holding back on killing the entire herd or predators then, some of these animal would still exist, Wolly mammoths for example.
KingCosworth (1 месяц назад)
The size of animals tends to be a combination of sexual evolution and available food.
Fabster Cola (1 месяц назад)
Giant Monotremes?
Shaun Davids (1 месяц назад)
well let's see ,reduced oxygen content in the air ,reduced nutrients in foods ....and it's that simple !
sina zarinabady (1 месяц назад)
My suggestion: increase mammal size please
Kaleb Martin (1 месяц назад)
Amphicoelias fragillimus was given its own genus (Maraapunisaurus) in a 2018 study. So that's interesting
Mr.Devil Luciferian (1 месяц назад)
Ironic but there's no dino-sized reptiles amphibians invertebrates etc...
Article 69 (1 месяц назад)
And animals started to become faster instead of larger
Calamitoso 00 (1 месяц назад)
The answer is easy, oye ancestors eat them
Kyler Janovec (1 месяц назад)
Are cardiovascular system is not like other genus’s
Kyler Janovec (1 месяц назад)
The lungs
Papa Ang (1 месяц назад)
I wish we saw some giant ass animals again
Lars van Brakel (1 месяц назад)
If a large mammal cooks itself, how does a whale work?
Lewis Castles-Hyson (1 месяц назад)
BLUE WHALE. Biggest mammal to ever exist. That sentence alone destroys your whole title and thus video. All that work for nothing. All because you have made a drastic error in relation to the factual incorrectness of your statement title.
Dustin Cordell (1 месяц назад)
because the earth has less Oxygen then it did 65 million years ago https://biology.stackexchange.com/questions/24336/bigger-animals-needs-bigger-amount-of-oxygen
Devin McCourty (1 месяц назад)
0:55 Palaeoloxodon namadicus (a straight tusked elephant) was larger than Paraceratherium
DesertScorpionKSA (1 месяц назад)
How long does a blue whale pregnancy last? Answer: 10 – 12 months. There's one reason that didn't make sense.
Womp Womp (1 месяц назад)
No giant mammals? Idk, I saw a pretty fat Mexican woman the other day.
G Nk (1 месяц назад)
It has only been around 65 million years since dinos went extinct. In the Triassic era which lasted for 50 million years the largest land animal only weighed 3 tons. Vs the larges land mammal that weighed 18 tons. So it isnt that surprising. If people didn't come along and wipe out the mega fauna you'd expect that they'd slowly get bigger and bigger when conditions allowed. So we're sorta the reason mammals wont get bigger... hurray humanity!
RTS (1 месяц назад)
"A warmer, muggy climate with a higher carbon content in the air made the vegetation grow off the hook." I wonder how many global warming alarmists chose to ignore that?
xXxSkyViperxXx (1 месяц назад)
arent whales giant mammals?
Battery Exhausted (1 месяц назад)
Elephants are giant
Arijit Kundu (1 месяц назад)
Thank u. It was quite interesting and educative too.
Lag Swag (1 месяц назад)
We killed them all and ate them.
zac figg (1 месяц назад)
palaeoloxodon namadicus was likely bigger the the indrocotherium, not in height, it would be roughly the same but in weight. up to 22 tonnes, the largest elephant to ever exist
Sonny Skye (1 месяц назад)
What about the giant humans?
Zacimus the master Shooter (1 месяц назад)
Wait 60 meters that’s twice the size of the blue whale 🐋 that would make it not the largest animal 🦓 on earth 🌎
Greatest Ever (1 месяц назад)
Well if I may interject, mmh mmh (clears throat). The moon is the reason we don't have giants anymore. Gravity. The moon is spinning away from the earth increasing the distance, scientists say one day the moon will spin so far away it'll wonder of into space. Even pangea broke up because of this spinning away of the moon. Imagine the moon a few kilometers closer to earth, this would ultimately affect the gravity on earth making it weaker. I think the low gravity made it easier for them to grow high as they were. But I don't have a degree so no one will believe me...
John DC (1 месяц назад)
You don't need to have a degree for people to believe you, you just need evidence.
Pedro Romano (1 месяц назад)
Your mom is the biggest mammal. (surprised nobody made this joke)
Themarenda (1 месяц назад)
I think due to lack of food, animal population grew over millions of years and it is easier to survive when you need less food, especially if ice age kicks in
Yoshi Tax-fraud-o-saurus (1 месяц назад)
Dinosaurs sued them for copying their size.
Ben Quinney (1 месяц назад)
Steve Taylor (1 месяц назад)
Not enough vegetation to support them
N D (1 месяц назад)
Some mammals lay eggs, mammals could develop air sacs over time, and blue whales don't cook themselves; how then is our size limited?
James Athersmith (1 месяц назад)
N D only monotremes lay eggs, air sacs aren’t a likely adaptation in mammals since they don’t really need them and whales live in the water which helps them to cool down.
irishbreakfast (1 месяц назад)
we hunted them to extinction biggest first and worked our way down the line. the African elephant and giraffe are the last giant mammals we haven't yet made extinct. but were working on it quickly.
Yup Tub (1 месяц назад)
Paleodoxon Namadicus reached up to 20 tons of weight.
Leonardo Feitosa (1 месяц назад)
Not to mention that elephant cells and mitochondria are already in cell terms doing everything on slow motion to compensaste for an elephants large size, so imagine whow slow the metabolism of a mammal the size of anphicocelias would have to be.
Titan Slayer (1 месяц назад)
Mammals suck! They have advanced brains, but still the way how they improve suck. Human can get only few babies when a crab can lay thousands of eggs once. The bigger the animal, worse the improving.
Tarbtano (1 месяц назад)
One thing to also take into account is aside from Sauropods, most dinosaurs didn't get over 2 or 3 tons. This means the African and Asian elephant are actually about the same size of many dinosaurs.
Emmanuel Araujo (2 месяца назад)
_Amphicoelias fragillimus_ didn't had 60m in lenght, it was an over-estimated measurement based on the original 1878 description. New studies show that he could be a rebbachisaurid and not a diplodocid sauropod, so they changed his species name to _Maraapunisaurus_ and did a new measured of his lenght that turned up to be around 30m. If we acknowledge the surviving evidence (which is very poor and could have typographical errors) and the biological plausibility of such a large land animal, I think we can agree on the point that the most recent studies are the ones we should rely on or at least we should discard the old ones. The biggest dinosaur we know of still is _Argentinosaurus huinculensis_ that could reach 30-35m in lenght and 80-100 tons of weight.
dynomax101 (2 месяца назад)
Information out of date, even for 2013. This video needs to be done over.
Nobushi Kensei (2 месяца назад)
Cause evolution sucks...
Randy Lee (2 месяца назад)
Lol just wait, rise in co2 nowadays relates to the beginning of life in history.
ATMOSK1234 (2 месяца назад)
Why would a bigger mammal have a higher body temp then a small one? If anything I'd think it would be lower since it has more mass to heat.
John DC (1 месяц назад)
A bigger mammal would have a higher core body temp because all of that heat generated from the mammal's center will be more difficult to dissipate, as opposed to small mammals in which the heat quickly disperses out. This is why some of the mammalian megafauna survived in the cold, it was because they were warmer and they stayed warm for longer
Opal Dust (2 месяца назад)
Reeee look how cute he looks with his braces
Andulvar (2 месяца назад)
So what I got from this is that this channel doesn't do research.
T.A.C (2 месяца назад)
Well I don’t think sauropods were exactly cold blooded, personally I think all Dino’s were warm blooded. I just think the sauropods produced less heat as they got bigger, gradually re-evolving a slower metabolism, and lower natural body heat.
Thom (2 месяца назад)
Saying "Erbivores" instead of "Herivores." Come on. I realise you might want to use the French pronunciation when talking about cooking, but other than that, these dinosaurs were not eating rosemary and thyme.
LitGeekSquad Official (2 месяца назад)
Because humans like big trophies
hunter hornet (2 месяца назад)
I thought the idea of superheavy dinosaurs had faded away. Some even suggesting that they may not have even weighed a third of the previous estimates.
piccolo Daimaku (2 месяца назад)
The big rhino lost his throne
Jack Doyle (3 месяца назад)
Isn't the most limiting factor humans? all the megafauna in the Americas and Australia was hunted to extinction when humans arrived.
seriously? really? (3 месяца назад)
So there are no large land MAMMALS but why arent there giant land REPTILES in the equatorial regions of the planet where vegetation is plentiful and so is the heat? We know the catastrophe that caused the mass extinction of just about all land creatures 64 m yrs ago. but the survivors were mostly of the reptilian sort, crocks, komodos stuff like that so why didnt they re-evolve to giants?
John DC (1 месяц назад)
Well one thing to know is that evolution doesn't just make and animal adapt if there are any free niches, if the animal populations are stable with the way they are they probably aren't gonna change. There's also probably too much competition if they wanna get biggger
Noob Saibot (3 месяца назад)
Its not carbon in the atmosphere, but oxygen saturation and pressure. There have been numerous experiments on plants (increased co2) and animals (o2 mainly with fish) to demonstrate this.
Nykko Smith (3 месяца назад)
Dinosaurs aren't real
8Bit.Jay (4 месяца назад)
This is alot more bareable if you watch it at 0.75 speed. Chill out Hank, what's the rush?
Prehistoric Creature (4 месяца назад)
Indricotherium is literally the size of a Sauropod. And Palaeoxolodon Namadicus is even Larger.
Malligrub 1 (4 месяца назад)
Wrong, relatively recently extinct straight tusked elephant was 6 metres tall and weighed over 22 tonnes
Sarah Leonard (4 месяца назад)
I'm a little confused. Most of the reasons stated in this video would also have applied to the giant mammals of the past, who DIDN'T cook themselves, or crush themselves under their own weight, or die out immediately due to low birth rates. So the reasons are rather severely flawed. The only one that appears to hold up is the reduction in food supply.
paco ramon (4 месяца назад)
Wait how the blue whale is the largest animal with 25 metres if there is a 60 metres dinosaur
A FUCKING WHITE MALE (4 месяца назад)
This video is very racist.
dondodda don (4 месяца назад)
Humans kill everything... Justsayn lol
Sama Lass (5 месяцев назад)
Here's a giant mammal https://i.ytimg.com/vi/aFKMZcr7ai4/hqdefault.jpg

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