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Why No Giant Mammals?

28006 ratings | 1772200 views
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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Text Comments (4124)
Prehistoric Creature (3 days ago)
Indricotherium is literally the size of a Sauropod. And Palaeoxolodon Namadicus is even Larger.
Malligrub 1 (14 days ago)
Wrong, relatively recently extinct straight tusked elephant was 6 metres tall and weighed over 22 tonnes
Sarah Leonard (19 days ago)
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 (19 days ago)
Wait how the blue whale is the largest animal with 25 metres if there is a 60 metres dinosaur
A FUCKING WHITE MALE (22 days ago)
This video is very racist.
dondodda don (23 days ago)
Humans kill everything... Justsayn lol
Sama Lass (1 month ago)
Here's a giant mammal https://i.ytimg.com/vi/aFKMZcr7ai4/hqdefault.jpg
Rigo Martinez (1 month ago)
Very likely there was a denser atmosphere back in those days
Rigo Martinez (1 month ago)
Yet intelligent design is out of the question. More whole in the theories of evolution than there is in Swiss cheese 🧀
Rigo Martinez (1 month ago)
I thought carbon was a product of human pollution
Air Conditioner (1 month ago)
If you think about it dinosaurs also had like 10 times the amount of time living to develop that big while mammals have only been around for like 60 million years ( as the dominant species)
Zeta Reticuli (1 month ago)
I recommend this video to people who still think humans grew to 60 meters tall and lived for 900 years.
Władca Wymiaru (1 month ago)
There is something that fit! Oxygen level! And warmth! Cretaceous period have up to 4000ppm of CO2 and 30% of oxygen! It was also longer and warmer than next period, by 4 °C than modern temperature! https://en.wikipedia.org/wiki/Cretaceous
viikmaqic (1 month ago)
smörgåsbord :D
Giant Sloths first died out 10,000 years ago.
Jasper Force (1 month ago)
But there were giant Wombats (the size roughly of At-At) in Australia fairly recently geologically speaking (within the last 100,000 years) and Australia has one of the warmest environments in the modern world... :s
Suhuyini Imoro (1 month ago)
i clicked on the vid just to comment BLUE WHALE then this guy ruins it .I guess it was a trap for people like me
TheLakabanzaichrg (1 month ago)
Today the largest mammals are the feminists.
Hans Hubner (1 month ago)
Global warming was good for the dinosaurs.
Prehistoric Matt (2 months ago)
And you think dinosaurs just laid eggs and walked away? Is your perception of caring parents stuck in the stone age?
Diana Snow (2 months ago)
Giraffes and elephants are pretty big
Kim Clayton (2 months ago)
I wished they still existed today.....providing they were vegetarians.  (gulp)!
Joshua davis (2 months ago)
I was waiting for him to say humans
Jagobot1 (3 months ago)
Does that mean that there is a possibility of these giant animals coming back if the environment allowed it???
PoopOnuGrave cameron (3 months ago)
What about roseane and oprah
PoopOnuGrave cameron (3 months ago)
What about rose and and oprah
tuffsmurfen96 (3 months ago)
The blue whale is a mammal! A better title would be "why no giant land animals", I think.
ApaProductions (3 months ago)
This is what you get when you have a non funny nerd reading jokes from a script
LGG (3 months ago)
Before even seeing it I said “Because they we’re too big to survive the Dinosaur’s Asteriod”
maximilianovvv (3 months ago)
ACKSHUALLY Amphicoelias fragillimus is of doubtful existance since "it's bones were lost" and only drawings remain...simply put there's no proof that it's the largest -and before you try to prove me wrong just google the history of why that is the case. So the confirmed largest species are the patagotitans.
polished x gamer gta 5 (3 months ago)
paleoloxodon is 24 tons and 17.1 feet tall at the shoulder making it the biggest land mammal
polished x gamer gta 5 (3 months ago)
blue whale is a mammal
brittany crawford (3 months ago)
Cause of humans
DGA2000 (3 months ago)
You're not making people smarter. More knowledgeable maybe
No B ucks (3 months ago)
Why u no like espicy foods?
Sniper_Kid_308 (3 months ago)
Well there are... Elephants
Holly Wood (4 months ago)
Whales are mammals
test (4 months ago)
younger dryas comet impact also wiped out the huge animals from the last ice age. like the dinosaur extinction, but for massive mammals.
UnicornyBANG (4 months ago)
I don't know that thing?!?!?!?!
Rursus (4 months ago)
No pauses between sentences => unlike.
Yeoj Henrie Sayadi (4 months ago)
Hi
kala captain (4 months ago)
>Why No Giant Mammals? because we killed them all
pronob mondal (4 months ago)
Nope paraceratherium (BM-17t and height-4.8 max) is not the largest land mammal..it is the palaeloxodon namadicus (BM- 22T and height-5m max) which is the largest land mammal ever recorded
Il Papa Vitielo (4 months ago)
The Platypus gives birth to eggs, so a giant platypus could work!
Dany Varna (4 months ago)
He looks as a liberal beta cuckold :-/
J Mondragon (4 months ago)
Also, humans. Most of that mammal megafauna they mentioned went extinct at almost the same time as human settlements started in the region. We are making nature evolve smaller, for it to survive us.
hunter hornet (4 months ago)
i thought this might be interesting until i noticed who is the presenter. i cant stand his annoying voice. at least i dont have him subscribed.
Broockle (4 months ago)
Dinosaurs cold blooded....? The small ones could be similar to modern reptiles but the really big ones probably had some amount of body heat I would imagine..... And Big Mammels could like Elephants adapt and produce less heat... why is body heat such a problem?
Lou Perez (4 months ago)
he's cute
Adro Harv (4 months ago)
we're supposed to believe that animals as much as 120 tonnes existed on this earth. Really
Peter Smythe (4 months ago)
Dinosaurs were definitely warm-blooded, as were crocodiles. Look at the physiology of modern crocs and birds and the fact that birds are warm-blooded? And of course that other archosaur, pterosaurs, which were fuzzy, flying animals that could not possibly have functioned on reptilian-level metabolisms.
Suceava Gamer Boy (4 months ago)
The blue whale is a mammal
Mr Pro Gamer786 (4 months ago)
Wow a paractheruim actually lived on walked this planet a few years ago
Harsh Srivastava (4 months ago)
But what about marsupial mammals? They give birth to poorly developed ones.
But there are, right? Whales?
Athina Mohammed (1 month ago)
ShadowTron specimens of ichtyosaurs rival the blue whale in size
Władca Wymiaru (1 month ago)
They are comparable. Like blue whales ~120 tons average. 190 was really FAT one...like fat elephant 12 tons...not count.
ShadowTron (1 month ago)
Blue whales are over twice the weight of the very largest sauropods.... sauropods have nothing on whales
Władca Wymiaru (1 month ago)
Some Sauropoda reaches whales weight :\
ShadowTron (1 month ago)
No that's completely false. They're the biggest because the water helps to prevent them from collapsing under their own weight.
notquiteordinary (4 months ago)
So, you have no idea in otherwords
Explain paracertherium from your thumbnail then they were bigger than elephants at 4.8 meters at shoulder and 7.4 meters long and weighed 15 to 20 tons
San dro (4 months ago)
This is pretty much same video as you got on PBS Econs "How Did Dinosaurs Get So Huge?"
Robert Szymanski (4 months ago)
I say the reason why there's no giant insects is due to the oxygen level going down...down... really! You got the internet here...look it up! If I went in a time machine and bring a giant dragon fly back...it wouldn't survived our low oxygen levels.....
copyRtest1 (4 months ago)
1:45 So one effect of C02 and Global Warming is that there will be more plantlife and in turn larger animals
TheIvangallo (5 months ago)
Don’t really care about this but it was in my recommended so...
Tom Holland (5 months ago)
More oxygen in the air. Spiracles limiting giant insects according to the oxygen content in the air.
Ascaithe (5 months ago)
You may as well ask 'why aren't any land animals alive today as large as the biggest in the past?'
Phoenix Gaming (5 months ago)
Giraffe
Jared McCain (5 months ago)
Dinosaurs never died out 65 million years and they still exist today
Abiy BattleSpell (5 months ago)
so ima guess whales are warm blooded and ok cause the water cools em?
Glasses&Tea (5 months ago)
Wow i forgot how long sci-show has been around watching this video almost 5years after it came out.
Amy Patchi (5 months ago)
Whose watching in 2018?
Israel Diaz (5 months ago)
well, dinosaurs just were giant wingless birds with feathers and warm blood.
Giannis Kalantzis (5 months ago)
The only issue I have is that Amphicoelis fragillimus was only speculated to be that big from a single fossil. However, a better example to say was the largest dinosaur would be an argentinasaurus, patagotitan or even bruhathkayakosaurus. Which grew to an estimated 37m long, not nearly as long as Amphicoelis. This is why many palaeontologist doubt the legitimacy of the fossil, as all we have that remains are sketches from it and sizes as given by the palaeontologist at the site.
Sailor Barsoom (5 months ago)
That's great, but what was NOT answered was: how do blue whales manage to be so big? I can get behind "they don't need the light bones because they're in the water" but what about long pregnancy and cooking themselves?
Hmmm Hmmm (5 months ago)
*PARACERATHERIUM*
WorldCitizen83 (5 months ago)
Because most mammals adapted to their habitat, that was getting smaller and smaller, because of the stupidest mammal of them all; ........? 50 points for the right answer.
maybe we go smaller by the time almost all of middle schools have short and average...kinda short people MAYBE WE GET SHORTER BY TIME
Mull M (5 months ago)
I always thought higher levels of oxygen in the time of the dinosaurs played a factor in their large size.
William Martínez (5 months ago)
Well the blue whales are massive
pokenei (5 months ago)
All speculations. Thumbs down.
Paul Mathew (5 months ago)
Yo mama so big....She is scishow topic....
Luke Schroeder (5 months ago)
Elephants?
Rum Mug the Orc (5 months ago)
Damn metric system!!!!!! 🤬 still a great video anyway!!!!
The Jurassic Warewolf (5 months ago)
customy units please
Hammerhead Monkey (5 months ago)
I'm happy with my size. Thank you.
whiteknightcat (6 months ago)
Why are there no megafauna? Because Noah couldn't get them on the Ark while the dinosaurs were stored as eggs. Ahahahahaha! (Now waiting for the Ken Ham wannabes to jump on this.)
Wasteland Wonderer (6 months ago)
But what about your momma?
Neil Coss (6 months ago)
What about whales (dozens of breeds) elephants (at least two breeds) bears, rhinoceros, hippopotamus, condors, etc. They're all pretty friggin' big.
Ross Catto (6 months ago)
Why dont whales cook themselves then?
Eleeth Tahgra (5 months ago)
Because of the massive volume of water around it.
whiteknightcat (6 months ago)
Ooh, good one!
Will-I-Am-Not (6 months ago)
No walking mammals? I can fix that. *grabs stapler and random bucket of horse legs*
Robert Tauzer (6 months ago)
When will this dino-reptile comparison finally die out? T rex was an animal much closer to eagle then to lizzard. Scientifically proven.
TheBestArOuNd (6 months ago)
Nice try, Blue Whales are estimated to be the biggest animals to ever exist; and you guessed it they are mammals
were they on the ark
Isaiah Naegi (6 months ago)
You forgot about Humans
proudblackjynx (6 months ago)
How do they estimate weight of dinosaurs
derR08IN (6 months ago)
Why do you always say metric tons? Isn't the ton already metric? 😅
derR08IN (6 months ago)
Thank you :)
whiteknightcat (6 months ago)
No. A metric ton (aka tonne) is the equivalent weight of a mass of 1000 kilograms. The common English unit of weight known as a ton (2,000 pounds) is by comparison a "short ton".
HD Campbell (6 months ago)
Amphicoelias never existed, it is no more real than Ultrasaurus. The largest real dinosaur is Argentinosaurus. The Sauroposeidon (which is probably just a huge Brachiosaurus) is also among the largest fossils. Use real science not hearsay.
kadir olav (6 months ago)
The big dangerous animals were shrunk so humans can live peacefully.
dave parga (6 months ago)
What I got from this is that ginat dragon are more plausible than like, horses.
Conner Alford (6 months ago)
Technically, the offspring housed in eggs are alive too.
Kur Norock (6 months ago)
Dinosaurs weren't reptiles. How do you not know that?
Ben H (6 months ago)
No mention of the fact that humans basically caused two extinction events which wiped out megafauna across the Americas and Australasia?
King Le (6 months ago)
Was that a paracer
David Stinnett (6 months ago)
This was the last chance for elephants to revolt and throw off the chains of their human oppressors and form an elephant society with elephant cars and elephant planes

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