/sci/ - Science & Math

>>15913947
I mean, look at the size of this thing, that's a rear foot!

Humans killed then all
Look at the Giant Ground Sloth and the Short Faced Bear in the Americas
Shortly after humans started to dominate these creatures vanished in favor of smaller versions

>>15913959

>>15913960

So many giants back then, never again has convergent evolution brought something like this back.
Very dissapointed with nature, I must say, very dissapointed.

>>15913947
too tasty

>>15913947
We are in a post-flood world.

The oxygen composition was much different back then that allowed these things to get real big. Too many trees died off over time, so now we got a lot more nitrogen than the dinos.

what was even the point of life if there were no humans?
i mean, think about it. humans are the only creatures with real intelligence and critical self-awareness. we are capable of learning and adapting, and that has allowed us to conquer the planet, and to advance science to the point where we even sent humans to the moon, and soon perhaps to other planets. humans are the most important species to have ever existed. and i would go even further and argue we are the only important species. every other species just kind of exists and lives a meaningless life. eat, breed, die.
what the fuck was the point life before humans existed?
at least modern animals have a reason to exist because they co-exist with humans. but back then, dinosaurs were just kind of "there".

>>15914113
You really thought you sounded smart typing that out huh

>>15914193
you could say that to anyone on /sci/

>>15913947
Oxygen levels.

We need megaflora to have megafauna.

About dinosaurs, the meteor fucked with all the giant animals, they are in a sense more fragile to these catastrophes, they need more energy, more food. Small animals can thrive and multiply much easier.

About the more recent megafauna that lived alongisde humans (mammoths, giant sloths, etc), they were all hunted down to extinction.

>>15914217
Yes but I find that post particularly offensive. He genuinely thinks he is saying something insightful and thought-provoking.

>>15913947
clearly their bone were made of something else, nothing could absorb enough calcium to become that big.

>>15913960
>Humans killed then all
probably white people did it

>>15914557
>Meaning of life
>Not thought provoking

>>15913947
earth is bigger, gravity is bigger

>>15914113
>what was even the point of life if there were no humans?
Off-topic

>>15914296
>Oxygen levels.
>We need megaflora to have megafauna.
Is that really the reason?

>>15914588
>clearly their bone were made of something else
I've never seen evidence of that, and plants contain plenty of calcium.

>>15914588
>>15914666
Their bones were hollow, they had air sacs inside them to lighten them up and allow them to move about at the size they got. A mastodon or an elephant is far more solidly built than any titanosaurs.
As to why organisms don’t get nearly as big anymore is partly because it’s really expensive, elephants need 500 pounds of food a day and argentinasaurus needed upwards of a ton of food a day. We don’t have massive continents with mostly the same biome everywhere like in the Mesozoic that could support these massive migrations needed to support them. Plus, grug saw big plant eaters and they had a lot of meat, hide and bone that could support his band for a moon cycle. Multiply this by upwards of 750,000 people and you get the idea,

The size of some of these vertebrae is just incredible.

>>15913947
more food.
the entire planet back then was either tropical or temperate.

>>15914708
>Their bones were hollow, they had air sacs inside them to lighten them up and allow them to move about at the size they got.
Yes, but convergent evolution would have taken care of that by now.
>We don’t have massive continents with mostly the same biome everywhere
Pagea was huge, it had plenty of geographical variation, it reached from the arctic to the antarctic circles, it had much topographical variation, and just as much coastal diversity, and the Jurassic + Cretaceous ages lasted for 145M years. It's simply impossible for the climate to remajn stable over such a vast continent, and such long duration.
What I am reading, and it makes some sense is that grasses had not yet evolved in the Jurassic, and vegetation seems to have beem mostly trees and tree-like plants, and in lacking competition from grasses, tress might have had the opportunity grow truly large, providing a large supply of plant matter for gigaherbivores to evolve. Plus, size is defense, yet another evolutionary force vector.
But, again, too vast of a time period, too vast of a continent for such broad statements.
Something very, very strange indeed happened in the Jurassic for giant sauropoda to evolve, very unique conditions permitted such evolutionary excesses. The Cretaceous doesn't surprise me as much since once that megafauna had evolved, it could have diversified and adapted to many different other environments over the many tens of millions of years.
Pity, it'd be so awesome to see something like that walk around nowadays.
Picture unrelated.

>>15914728
See
>>15914731

There was a lot of food back then. Giant trees covered the whole planet.

>>15914751
>Giant trees covered the whole planet.
Not true:
>The megamonsoon would have led to immensely arid regions along the interior regions of the continent. Those areas would have been nearly uninhabitable, with extremely hot days and frigid nights
>The evaporites in the geologic record suggested vast and extensive regions of persistent dry conditions near the Pangean centre
https://en.wikipedia.org/wiki/Pangean_megamonsoon
The vast geographical variability was also adressed here:
>>15914731

>>15914731
>Yes, but convergent evolution would have taken care of that by now
Birds have them because they are descendants of therapsids. Lung and airsacs evolved during the late Permian/early Triassic because the air was starved of oxygen by the great dying eruptions, which also caused synapsids to evolve a diaphragm.
>size is defense
Yes, sauropods were fuckhuge to deal with large, powerful predators like tyrannosaurus, but is still very expensive. Mammoths were huge enough to deal with most predators around, and even by the time humans came to North America, the predators they faced like homotherium and smilodon were already on the decline, so there was no need to get any bigger.
Earth was also much hotter and had more CO2 that fueled plant growth more than the cooler, drier climate of the Pleistocene which made plant food more available across a lot more of the earth’s surface

>>15914788
I'm not saying they were all over retard. I'm saying there was a lot more tree cover with massive trees than there is today.

>>15914805
>Birds have them because they are descendants of therapsids.
Yes, thank you. To clarify, I meant that convergent evolution would have found other or similar solutions to gigantism's limitations under sufficient evolutionary pressure, bar true impossibility, which in a way is what we're pondering about.
What is extraordinary is that titanosauridae went far beyond the size that would already hinder predation from large theropods. T-rex, as huge as it seems to us, is but a puppy next to a titanosaur.
Could thhis have been genetic drift, or preferential selection towards large and larger sexual mates?
It just seems that beyond a certain huge size, beyond what th largest carnivore can effectively prey upon, would be a negligible defense improvement. Once you're already huge, why be bigger huge, lol.
But then again, the same can be said about roqual whales. Orcas (save for sperm whales) are the largest toothed predators out there in the oceans that can possibly take on an adult whale, but we know that they only do that with sick and isolated rorqual individuals, but yet rorquals kept evolving larger and larger, much larger than orcas.
Picture: reconstruction of Sue

>>15914812
>retard
Insults? No reply.
And yes, you did type it.

>>15914823
Are you a zoomer faggot that cries when they are called a retard in a site where the name is commonly substituted for anon or faggot? Or are you just an autistic faggot who feels like they need to be pedantic about everything in order for their lives to have meaning?

>>15913947
I believe they were actually consumed by birds. Nothing that big could defend from flying, flesh eating monsters with beaks that can pick it apart alive. Life had to evolve big anew, resistant to the birds, but the birds may forever pose a limit.
>>15914588
>>15914731
Whales don't seem to be any trouble with it, and their bones are super thick.

>>15913947
I believe they were actually consumed by birds. Nothing that big could defend from flying, flesh eating monsters with beaks that can pick it apart alive. Life had to evolve big anew, resistant to the birds, but the birds may forever pose a limit.
>>15914588
>>15914731
Whales don't seem to have any trouble with it, and their bones are super thick.

>>15913947
I believe they were actually consumed by birds. Nothing that big could defend from flying, flesh eating monsters with beaks that could pick it apart alive. Life had to evolve big anew, resistant to the birds, but the birds may forever pose a limit.
>>15914588
>>15914731
Whales don't seem to have any trouble with it, and their bones are super thick.

>>15914862
>Nothing that big could defend from flying, flesh eating monsters with beaks that could pick it apart alive.
Wevenever found fossils of oterodsctils of prey that big. Even quetzalcoatlus appears to have been either a surface-skinmmer fish eater or a terrestrial stalker, similar to modern storks.
I can't imagine a pterodactyl who could effectively prey on titanosaurs, but who knows what else still remains buried in the rocks.

>>15914868
Pterodactyls of prey*
Fixed

>>15913947
https://www.scientificamerican.com/article/how-sauropod-dinosaurs-became-the-biggest-land-animals-again-and-again/

>>15914788
Pangea didn't exist at the time of Titanosaurs though

>>15914882
That is true, it had already begun splitting apart

>>15913989
This but sans irony.

>>15914609
Aside from the fact that you're a massive faggot and everything you said is stupid, you're asking a philosophical question which you clearly know there isnt any definite answer for. I'm 100% sure you're one of the smoothbrains who keeps spamming consciousness threads for the same reason even though that discussion has been had a million times.
You do it because you want to feel smart and jerk yourself off without needing any prior knowledge or understanding of a topic because any retard can talk about
>dude...like....what's the meaning of life bro
Look at the title of this thread and tell me what the fuck does that have to do with the meaning of life.

>>15914868
I'm talking about birds, which could feast of them like vultures do on a carcass, but when the giant animal was still alive.

>>15913947
>>15913959
>megafauna

That is megaplaster.

>>15914939
I see what you mean. Thiugh there is no evidence for that, sauropods might have had ultra thick skin to prevent that, it only makes sense, or they just knew how to shake proto-birds away.
How do giraffes deal witn birds, for example?

>>15913947
we do but we nearly drove them to extinction.

>>15915192
>Why don't we have true LAND megafauna anymore?

>>15915192
Old and busted news straight from the 90s, and I mean 1890s.
They have now found an Ichthyosaur that is the candidate for largest species or being to have ever lived.

>>15915011
I suppose that mammals are agile enough to not make it worth the effort for the birds. A giraffe won't stand and wait to be eaten.

>>15913947
Bruhathkayosaurus beats Argentinosaurus

>>15915192
>oy vey muh precious whalerinos!!
>immam gooonnna save them from the le big bad boats!!!
>am i a good boy yet!?!?!

>>15915708
>A giraffe won't stand and wait to be eaten.
Apparently, neither did sauropods. Or maybe there just weren't predatory birds that would take on megafauna by picking at their necks and backs. Even nowadays we don't see rhinos, or elephants, or buffalos, or bison, or hippos being picked to death by birds.
In fact, I can't think of any such case nowadays.

>>15916397
Interesting, thanks! It seems the original fossils have been lost or destroyed. Pity.
>However, all of the estimates are based on the dimensions of the fossils described in Yadagiri and Ayyasami (1987), and in 2017, it was reported that the holotype fossils had disintegrated and no longer exist.[
https://en.wikipedia.org/wiki/Bruhathkayosaurus

>>15914113
These are all subjective accomplishments. But everything in life is subjective.

>>15914862
whales aren't on land, if they were they woudn't be able to move

>>15913947
We don't know how large the meteor that hit was
Might've increased the earth's mass/gravity

Alternatively we might've had a thicker atmosphere allowing them to float like whales do in water.

>>15914615
people ignoring the one right post instead going on about nonsense like "there was more oxygen" the laws of physics don't change, for something that big to exist gravity would have to be less, and it was

>>15916746
Are you a bot?
>>15916825
Irrelevant.

>>15916889
Why would I be a bot if I'm having an educated conversation with you?

>>15916829
>We don't know how large the meteor that hit was
If you're talking about Chicxulub, we have estimated the size of the impactor.
>we might've had a thicker atmosphere
No evidence of that in the geologic record.

>>15915637
>They have now found an Ichthyosaur that is the candidate for largest species or being to have ever lived.
Do you mean shonisaurus?

>>15916833
Nope, giant dinosaurs are fully within the bounds of possibility in animals.
Mammals do not get that big in part because mammals carry pregnancies rather than spamming eggs.

The fact that early sauropods evolved when they did (right in the "gigantification arms race" era of recovery from the previous mass extinction) AND were R selected was the reason they blew up to insane size. Let me explain.

Beyond a certain size, sauropods became untouchable. Very few sauropods that hatched ever reached this escape from predation, but when they did, they were free to roam the world converting food into thousands of eggs, meaning the sauropods that were best at attaining great size were dominating the gene pool. As predatory dinosaurs attained bigger sizes, sauropods needed to go even bigger, to afford laying larger eggs at the same high rate of production.
The reason why sauropods attained such sized when no other land animals ever did comes down to several coincidences of anatomy, listed here.
1. Sauropods had pneumatically supported skeletons, making their bones lighter for the same strength.
2. This pneumatic gas bladder system was also connected to their lungs, which gave them more efficient oxygen absorption.
3. They likely had efficient means of dumping the heat produced by digesting literal tonnes of food, meaning they both didn't need to burn extra calories to stay warm, and they could handle a wide range of habitats without getting too cold or too hot.
4. Sauropods didn't chew their food. Instead they swallowed stones and grit to grind food in their stomach: this allowed their heads to stay very lightweight, much moreso than if they needed a powerful chewing jaw, and allowed their necks to become very long, increasing the volume of food they could access.
5. Sauropods could eat fast: No chewing means the animal can just grab and swallow food in bulk, potentially increasing its daily caloric intake maximum by several times over.

>>15916397
https://youtu.be/Z1BBKS2bTnA?si=NDK2ytz2L-9enJJ4

>>15917640
>This pneumatic gas bladder system was also connected to their lungs, which gave them more efficient oxygen absorption.
This makes me wonder: how vulnerable were these creatures to pulmonary infections, and consequentially, a full-body airsack infection? It'd seem it make them extremely vulnerable to such outcomes, no? Their immune systems must have been highly specialized against such kind of illnesses.

All else you mention, thank you for that, the article I posted above covers much of what you said, recommended.
>>15914879

Nonetheless, it still doesn't answer my original question: where is the comparable gigantism in the cenozoic that we saw evolve so many time during the mesozoic?
Why did reptiles never get as large again?
Why didn't land mamals?
Paraceratherium was huge indeed, but it was a one-off. Mastodons got large but not nearly as large.
Or how about monotremes for example, why didn't egg-laying mamals not get giant? Those don't have to carry larger and larger gestating offspring!

If huge sauropda had been one-hit-wonders, it'd make more sense, but they weren't! Many times they convergently evolved so! Not just that, but with morphological differences significant enough to have occupied different ecological niches, in the same habitat. What?!? How?
Absolutely incredible, truly baffling.

>>15913947
>>15917983
Congrats on beginning to wake up. Everything you think you know about the history of this planet is a lie.

>>15913947
The planet is just recovering from the deluge that happened 11.6K years ago. Eco systems eventually are towered by huge monsters, but this time mankind is taking that place by being the apex predator.

>>15917983
>Nonetheless, it still doesn't answer my original question: where is the comparable gigantism in the cenozoic that we saw evolve so many time during the mesozoic?
>Why did reptiles never get as large again?
>Why didn't land mamals?
>Paraceratherium was huge indeed, but it was a one-off. Mastodons got large but not nearly as large.
>Or how about monotremes for example, why didn't egg-laying mamals not get giant? Those don't have to carry larger and larger gestating offspring!

Placental animal size limits come from the K selected reproductive strategy that large mammals are pretty much forced to use.

Placental mammals could never get as big as sauropods without sustained and strong evolutionary pressure to evolve those traits that enable largeness.

Archosaurs never got as big again because mammals were generalist and high metabolism enough to take over most empty niches before reptiles could radiate.

Monotremes didn't get large because placental mammals out competed them. If a population of monotremes were allowed to evolve under selective pressures favoring largeness for sufficient time to reach gargantuan maximum sizes, Monotremes may have one day rivalled Sauropods, but they didn't evolve in an environment which favored largeness.

You may as well ask why only Sequoia Redwoods have evolved their immense height and girth, when presumably all trees should maximize for size. The answer is, they're the only trees to have evolved in an environment which selected for enormous girthy trees 300 feet tall. There's really no deep mystery.

imagine being an adult and believing dinosaurs were real

>>15918411
Keep it in mind, anons, thank you. You know what to do.

>>15918018
This one as well, trolling outside of /b/, you know what to do anons.

>>15918321
>but they didn't evolve in an environment which favored largeness.
Yes, I too concluded that. Somehow it just didn't happen in the 65M years during the Cenozoic, for no animal group. But that's an obvious and vague answer. What exactly is odd here? Was the Mesozoic a very special era since those evolutionary pressures were continuously present, gigantism having evolved multiple times? Was it a special era? Or is it the Cenozoic that is special, never having pressured land fauna in that evolutionary direction?
Mammals evolved gigantism in the seas, so gestating huge fetuses for a mamal isn't a problem in itself, but carrying one inside on land might be a deal-breaker.
Why didn't monotremes feel the pressure to evolve gigantism, for example?

>>15913947
The thunder got too bad

>>15914113
>dinosaurs were just kind of "there"
So are you.

>>15914596
Anything white people are blamed for is of Jewish fault until proven otherwise

>>15913960
/thread

We killed and ate them and or killed and ate their prey.

>>15918741
>What exactly is odd here?
For the first time, placental mammals dominate all megafaunal niches on land, except for tiny outliers like isolated islands.

Before the KT extinction, archosaurs reached giant size across many lineages, and only the sauropods reached supergiant status, easily dwarfing the largest ceratopsians and hadrosaurs. All dinosauria had erect limbs, making supporting body sizes larger than a cow practical, and they all laid eggs, thus weren't held back by the size limit imposed by pregnancy. All of the biggest non-sauropod dinosaurs topped out at around the same body mass/size as the anomalously big indricotheres and elephant relatives like paraceratherium. Only Sauropods developed the right traits to go beyond those limits significantly.

Before the Permian extinction, few terrestrial animals had erect limb posture, and those that did were predators. Herbivores themselves were likely size limited by food availability moreso than limb posture, due to Pangea being nearly entirely covered by harsh desert.

My hypothesis is that niches exist to support supergiant land animals even today, but are left unfilled due to a quirk of mammalian biology. That is to say, if we resurrected a giant sauropod species today, assuming it didn't get sick and die from eating modern plants, it could grow to just as large a size as anciemt sauropod dinosaurs attained while remaining healthy.

>>15913947
I'm fond of the Earth changing size theory.
Smaller planets tend toward larger objects, and vice versa due to gravity.
Earth was smaller and expanded somehow or increased gravity.
Sharks are just the old minnows.

>>15913947
Oxygen levels are lower. Know how you can increase oxygen? Add more atmospheric CO2 for plants to photosynthesize.

>>15919976
>Smaller planets tend toward larger objects, and vice versa due to gravity.
Of course, which is why the smallest planet is closest to the Sun, followed by the 3rd smallest, 4th smallest, 2nd smallest, biggest, second biggest, fourth biggest, and third biggest, with a belt of tiny objects between the biggest and 2nd smallest, and an even bigger belt of medium sized objects way past all the big objects. Dumbass.

>>15920114
What he means is that larger creatures are possible on smaller planets. I think you misunderstood him.

>>15913964
Fuck off you piece of shit.

>>15920117
Animal size on Earth is limited by food intake capacity, not gravity.

>>15920385
So the limiting factor is our catastrophically low CO2 levels curtailing plant growth?

>>15920391
No, there exists enough food mass in general already. The issue is literally just that modern big terrestrial animals need to chew with the same structure they eat with. Sauropods didn't have this limitation, so they were able to grow huge. Baleen whales don't have this limitation either, so are also incredibly huge. Even sperm whales don't need to chew.

>>15913947
I'm working on it. Planet has to be significantly warmed back up and the humans have to be removed first.

>>15916751
Also indian so don't believe they were ever around. Pajeets are cartoonish in their paleontological bullshit, like the chinks.

>>15913947
Those were small when they were deposited

>>15919976
>I'm fond of the Earth changing size theory.
>theory

extremely limited brain function, completely razor-thin calorie requirements and migration cycles that coincided with the seasons

>>15920860
>Pajeets
There could have been a conversation. Too bad.

>>15921186
What are your pronouns, hon?

>>15921065
I’ve always thought this in the back of my mind but there’s literally no hypothesis available to explain how these bones would grow in size.

>>15919976
The entire asteroid belt amounts to about around to about 0.05% of Earth's total mass (most of which is from a couple of objects like Ceres). If we assume that a 2% increase in gravity would be enough to have an appreciable effect on biology that would outweigh other factors like food availability and competition (note: it wouldn't) you would need the equivalent of 40 asteroid belts, 10 Plutos, or slightly under 2 Moons to crash into the Earth. That would have significantly greater effects on life than killing off dinosaurs and making subsequent animals smaller, and would be orders of magnitude more destructive than a full scale thermonuclear war.

>>15913947
Air sacs

>>15921384
What makes you think that it requires all that crashing to add mass to the planet?

>>15915637
Aust ichtiosaur?
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0194742

>>15918741
>Why didn't monotremes feel the pressure to evolve gigantism, for example?
Placentals, Marsupials, and Monotremes all produced relatively large animals at some point. But the conditions that fostered those trends changed, and large mammals have almost disappeared from most niches.