Do Thunderbeasts Prove Giant Animals Are Inevitable?

[@eons]

You can get the 2024 Eons calendar here! store.dftba.com/collections/eons

[@drstone3418]

Most small animals like fish reptiles and rodents and insects have larger brain body size as body gets bigger brain gets smaller by comparison

[@ConstantChaos1]

Idk i think im pretty constant along with change

[@andrabook8758]

You know that most of our ''legends", like the one about "Thunderbeasts", actually point towards human overlap with those species, right? Even tho we have yet to find proof today that humans existed back then all the oral traditions would point in that direction technically speaking. And they've been that way prior to the invention of Paleontology. I just find that interesting. We could be off with the evolutionary timelines by quite a bit there :)

[@ConstantChaos1]

@andrabook8758 oh no we fully know humans were in the America's at the same time as these creatures, the earliest fosil evidence of humans in the America's is 23,000 BCE from a footprint recently found in and 25,000 BCE from sloth bone pendants in Brazil. We were definitely here at the same time

[@timeshark8727]

There is also a preservation bias towards large, thick-boned, animals. Animals below a certain size only leave traces under very specific conditions, their remains just don't last long enough for gradual burial.

[@snakesandstones4252]

Thank you for mentioning this!

[@rosstacoman5910]

survivor bias....?

[@RockChalk263]

@@rosstacoman5910 as in thin-boned and small animals aren't as commonly preserved in the fossil record. Since thick-boned and large animal bones are more likely to be preserved, this can skew the perceived population % and give an illusion of a higher "fitness" than the smaller animals that have a much lower chance of getting fossilized.

[@shnilikmw]

Yet trilobites are the most common fossilized organism you’ll find.

[@timeshark8727]

@@shnilikmw True, its a bit different for invertebrates thanks to the exoskeleton, they fossilize fairly well compared to vertebrates. Bottom dwellers also have a preservation bias because its very easy for them to end up buried quickly compared to things that live in open water.

[@Tungdil_01]

Hey PBS Eons crew, one suggestion: when you display the references, I recommend using the DOI link rather than the webpage. The reason is that the DOI is said to be 'eternal', while the journal webpage can change for multiple reasons. So by using the DOI link, in the future people will still be able to see the references. Great video!

[@SoulDelSol]

What's a doi link

[@Tungdil_01]

@@SoulDelSol "A DOI, or Digital Object Identifier, is a string of numbers, letters and symbols used to uniquely identify an article or document, and to provide it with a permanent web address (URL)."

[@SoulDelSol]

@@Tungdil_01 cool. I never knew that

[@athaya2992]

agree, i hope they see this

[@CharlesEros1]

But you can change the log (or what is said in it) and what if they remove the page and update it with a new one which is common, You would end up being directed too adead page. Close enough always is better then accurate for now surely.

[@MorgottTheGraceGiven]

It’s honestly really cool to think about how we’re living at the same time as the largest mammal (blue whale) and the smallest dinosaur (hummingbird) to ever exist!

[@4thdimensionalexplorer]

In surviving fossil records perhaps. No reason to think small creatures didn't live in the past woth so many niches fir them to fill

[@Jason75913]

The surviving fossil record only shows us a tiny glimpse into the past. We'll never even know the half of it.

[@ianism3]

*as far as we know!

[@Rarasrevenge]

@@Jason75913not even a half It’s proposed that we only know about 0.1% of life that was on earth

[@mjm3091]

Technically the mammal part may not be fully true anymore as new fossils found in recent years imply existence of bigger whales.

[@kweassa6204]

I think it can also be said that we're actually "giants" ourselves. When compared to most of the animal kingdom, we're actually pretty huge. Larger fauna like horses, cows, deers, elephants and other carnivores leave a striking impression to us and we feel that we're not all that large and powerful, but even when limited to just our own mammal kingdom we're one of the largest animals out there.

[@TheFanatical1]

Yeah people say "humans aren't that big!" this but among mammals humans are actually pretty massive. Everything bigger than us by a meaningful amount is actually not that much bigger, not compared to the kind of size ratios dinosaurs routinely reached, or even compared to the ratios we make with other creatures.

[@naamadossantossilva4736]

We are in the great ape group.Our size is far above the norm for primates.

[@Oinker-Sploinker]

it's like when people say human's are weak by comparing them with the strongest animal's around.

[@LimeyLassen]

There's some argument over what "megafauna" means, and under some definitions humans do fit.

[@kevindolin4315]

By simple numbers, humans are by far the most common large animal among all species. Think about it. How many times have you encountered an animal larger than you, outside of zoos or farms? As we become more and more urbanized, the creatures we encounter are much smaller than we are. While there are a number of animals considerably larger than humans, they are far less represented in nature compared to most species. Not only are they far less common, some are becoming less so, some to the point of extinction.

[@invisiblejaguar1]

I've recently come to think of 'therium' being the mammalian version of the dinosaur/reptile 'saurus'. These do well for naming any species of mammal or dinosaur in standard cases.

[@AndrewTBP]

Correct!

[@lordsrednuas]

"Theria" is the clade of mammals that give birth to live young, so all placental mammals and all marsupials. Monotremes (mammals that lay eggs like the platypus are not in this group). So you're right, it is the mammal version of 'saurus', at least for mammals that don't/didn't lay eggs.

[@pengen_gantinama]

Meanwhile poor therapsids have to choose either Saurus or Suchus

[@beastmaster0934]

And like how almost every crocodilian has the suffix “suchus” to its scientific name.

[@educationforblind6362]

Mammalian originated in reptiles

[@blackburned]

Blake is such an incredible host. He covers the material is such an understandable way and has a great sense of humor. I got a good chuckle that Kallie made Blake say he says "Honey I shrunk the wife" when he didn't want to 😂 the whole team is so funny

[@StonedtotheBones13]

I think it was life not wife?

[@dier7144]

It’s absolutely crazy to think at the same time we have one of largest animals ever to exist but we also have some of the smallest animals compared to other time periods

[@bri1085]

Wouldn't by the fossil record favour larger animals?

[@johnellis3383]

Good point

[@pedrosabino8751]

​@@bri1085Yeah, a bias of the survivor

[@spindash64]

“I eated them all :(“

[@joema500]

@@pedrosabino8751 I don't think it's that it's just that their bones were bigger so were less likely to be destroyed.

[@mrsanity]

There's some element of preservation bias in the number of bigger animals in the record, plus some habitats in which larger sizes become a hinderance after a certain point are also very bad at producing the conditions for fossilisation. There's likely a whole bunch of sheep sized brontotheres that left no trace for example.

[@apnosaurus]

Most people probably have heard Brontosaurus was really Apatosaurus, however a 2014 study found enough diagnostic characteristics to revive the genus, and it did so completely by accident. Not everyone agrees with this paper, but for now Brontosaurus is a distinct genus.

[@spindash64]

We're so Brontack

[@SoulDelSol]

Brontosaurus is eternal. I remember when they tried ro dash its memory away

[@MossyMozart]

​@@SoulDelSol - Noooo! They are treating the Brontosaurus with the same disregard they treat Pluto (now a "dwarf plane" - in other words.....a PLANET! !).

[@SoulDelSol]

@@MossyMozart yes we grew up in a world with 9 planets including pluto and brontosaurus as the most popular of giant sauropods and I wouldn't have it any other way.

[@Rich4098]

Here's my theory according to many computer games regarding evolution I've played. Bigger is always better when the environment is stable, but if the environment changes there is a greater risk of sudden extinction. Smaller animals can usually adapt more quickly for various reasons, including that they almost always reproduce at a much higher rate.

[@SoulDelSol]

They don't need as much food either

[@L333gok]

Considering that humans are bigger animals, and the environment is becoming unstable due to climate change, does that means humans are about to go extinct?

[@KermRiv]

Shelter is also a lot easier to get when you're small

[@mcgritty8842]

@@SoulDelSolwas about to say that too. The bigger you are, the more you need to survive

[@wezul]

From what I've found online, there is a benefit to being bigger in the form of energy conservation. At least for ectothermic animals. Small animals lose heat to their surroundings faster than large ones, and large animals need proportionally less food per pound of body weight to live. So if you were designing an animal from scratch to be as efficient as possible, bigger may indeed be better. I would LOVE a more in-depth exploration of this topic though!!

[@kyle857]

Big animals are niche specialists. Animals getting bigger until their niche collapses, then other animals grow and specilaize to fill it till the same thing happens again.

[@gwenpoole1071]

Watching Blake crack himself up always kills me 🤣🤣🤣 especially when he laughs at sillier jokes than most of the other hosts but then pretends to be unmoved by their puns 🤣

[@pteranodon6612]

Being bigger allows the animals to enter ecological niches that would otherwise be impossible. Like being able to move heavy objects to gain access to food. The main drawback is that big animals are much more likely to go extinct during a long period of food scarcity.

[@anyascelticcreations]

Hmm. I'm no expert. But when I snakesat for a herpetologist friend for 2 weeks he had me feed all the medium and small sized snakes every day. But he said that the large snakes wouldn't need to eat for the time that he was gone. To me, that kind of shows the opposite to be more likely as far as who would survive. 🤷‍♀️

[@jenerix5257]

​@@anyascelticcreations Also not an expert but (part of) the reason for deep-sea gigantism is that larger animals can stockpile more energy. My understanding is that large animals are more resilient to inconsistent supplies of food while small ones can survive better on a consistently low supply.

[@anyascelticcreations]

@@jenerix5257 Oh, that makes a lot of sense. I like that you pointed out the pros and cons rhat way.

[@The_Worst_Guy_Ever]

@@anyascelticcreations That reasoning is a little flawed. House cat’s can survive 2 weeks without food, but elephants can only survive for about half that long without food. Also most reptiles (even the ones that typically eat every day) can realistically go several weeks without food before they starve to death. Gila monsters are pretty small and yet they only need to eat 2 or 3 times a year. But I’d assume the main reason why giant animals are more susceptible to starvation is just due to the fact that it’s far easier for them to deplete their food source just because of how much they need to eat.

[@miriam-english]

Love this series. Thanks folks. Keep up the great work.

[@kevincronk7981]

Edward Drinker Cope has had my favorite name I've heard in a while, I did not expect a video about him without anyone breaking out into laughter

[@hcn6708]

Too bad he’s a huge racist F

[@dstinnettmusic]

I think size is an “easy” thing for natural selection to make happen, but that smaller animals can out-compete them if they use social structures.

[@bkjeong4302]

The idea smaller animals dominate over and outcompete bigger animals by being “smarter” and more social flies in the face of reality for many reasons: - being smaller =/= being more social. In fact we see more cases of larger animals being more social than smaller relatives (the most social canids are the big-game hunting large predators like wolves or painted dogs, and not the smaller mesopredators like jackals or foxes; lions are far more social than most other cats and are also among the largest cats of recent times, being beaten out only by tigers and some of the Late Pleistocene large cats, the latter of which may also have been social; the spotted hyena is the only social hyena of the Quaternary and also the largest; etc). - being social generally isn’t enough to overcome size disadvantages even if you have the numbers. Tigers and bears dominate over entire packs of wolves, for example, even though they are largely solitary and wolves are very social. The most the smaller, “superior” “more sophisticated” animals can often do is to harass the larger, “dumber”, “primitive” animal until it’s annoyed enough to give up, which is misrepresented in media as “brain beating brawn” when in reality it’s defensive behaviour by prey species or by a less dominant species to deal with a predator that they can’t realistically beat outright even in groups. Geese can harass and scare away humans, does that mean geese are outcompeting us or are smarter and “better” than us? - being smaller usually means you’re not actually able to fill the niches of larger animals in the first place, meaning there isn’t much competition to start with. Nature isn’t a case of “David beats Goliath” as people increasingly seem to assume. Being big does have its disadvantages, but being unable to compete with smaller, supposedly “better evolved” animals is not one of the issues. Nine times out of ten, a supposed case of big animals being “outcompeted” by smaller animals was actually the result of another factor the smaller animals had nothing to do with, such as mass extinction events, climatic changes, or human activity-which are the ACTUAL issues big animals can’t cope with. The fact smaller animals are better at surviving such things does not mean they tend to outcompete larger animals (because surviving for longer literally isn’t the definition of competition).

[@AugustSchroif]

>I think size is an “easy” thing for natural selection to make happen Can you explain this to my D?

[@christiancinnabars1402]

@bkjeong4302 They never said that being smaller means being smarter or more social. They said that a smaller animal _could_ outcompete a larger animal _if_ they use social structures.

[@bkjeong4302]

@@christiancinnabars1402 But even that part is massively iffy (read the rest of my comment)

[@jakobraahauge7299]

Personally I follow Cope's rule - but I'm also from such an ancient lineage that scrawny was in vogue, when I was young

[@tec-jones5445]

Speaking of recent megafauna, Dane Pavitt did a great video about shifting baseline syndrome and how large animals have been the norm in the fossil record, which I definitely recommend. We live in a time of low biodiversity, especially for large animals, rather than prehistoric animals necessarily being larger, and as a result, many tend to think that smaller animals are the norm or that animals used to be bigger. Of course, bigger is not always better, but it is interesting how common large animals have been in deep time and how weird/troubling their absence and/or decline is today.

[@Dragrath1]

One problem with drawing this kind of conclusion is that we also know that there is a selection bias which must be accounted for as smaller animals are much less likely to fossilize in part because their remains are more easily scavenged or destroyed(by erosion). Small animas today particularly arthropods also tend to have fairly restricted ranges even when accounting for habitat fragmentation at least compared to larger animals which can more readily travel long distances. This is important to consider since fossilization is biased in terms of what sort of environments lead to fossilization as only depositional environments can produce fossils meaning places like dry floodplains that experience episodic flash flooding events, anoxic water zones, and active plate margins(for both terrestrial and costal marine) are heavily overrepresented in the fossil record compared to environments which are erosive or have slow rates of sedimentation. Landslides and pyroclastic flows seem to be particularly prominent in terms of high quality fossil localities. For creatures which lived outside of these high fossilization rate zones we largely lack any knowledge of what may have lived in those areas as Additionally researchers themselves have a size bias in fossil identification and collection which has become particularly important in tracing down ancient animal lineages from the Early Cambrian and Ediacaran where efforts to search through and characterize small grains of sand have identified several microscopic animal fossils. While it is possible that there very well may have been more bigger animals than smaller animals in the deep past the fact remains that there are many biases in play which are likely to selectively favor large animals being fossilized over small ones.

[@tec-jones5445]

@Dragrath1 I understand these biases, and thank you for pointing them out, as they are very important to acknowledge. The fossil record is very incomplete. Though I was more trying to explain that having a higher diversity of large animals was the norm for much of prehistory, and that we live in a world deprived of diverse megafauna by comparison. Not that there were more larger animals than smaller ones. Of course, smaller animals will outnumber larger ones in terms of populations and diversity, even if that isn't always reflected in the fossil record. My comment was more addressing the misunderstanding of how people tend to think that animals "used to be bigger" when comparing prehistoric life to today. A healthy biosphere should have diverse species and populations of all sizes.

[@joseguerreiro5943]

Yep. As soon as humans set foot on a continent the megafauna living in those continents mostly got extinct. It happed with Europe, Australia, North America and South America. The only megafauna that managed to survive was the Africa one, because they were lucky enough to have co-evolved alongside humans and were therefore better prepared.

[@tec-jones5445]

@joseguerreiro5943 While that is definitely a factor, I'm not quite sure if it's that simple. While many extinctions do correlate with human arrival, many other species of megafauna coexisted with hunter-gathererr humans for longer periods of time before declining. For instance, while the extinctions began 13,000 years ago in North America, more recent archeological evidence like the footprints in White Sands National Park, may suggest that humans were present there for much longer, possible starting at least 20,000 years ago, if not longer. With at least 7,000 years of experience living with humans, the sudden decrease in megafauna 13,000 years ago seems rather peculiar to me. Particularly for animals that we don't (yet) have evidence of human hunting for, like horses and camels. There were also some species, like Bison antiquus, that were likely hunted by humans, but survived the extinction. On top of that, while Africa suffered the least, there were still extinctions there too, and southern/southeast Asia and the Indian subcontinent show similar extinction rates, despite humans arriving there later (granted there were other human/hominin species living alongside animals there they might have learned to deal with).

[@Dragrath1]

@@tec-jones5445 Oh absolutely yeah large animals have been a regular part of ecosystems for as long as biology has supported them with many of the limitations on size being related to overcoming physiological limits. For example Sauropods immense body sizes were possible only due to a conflux of biological adaptations which allowed them to overcome the normal weight limits that confined other animals for example: Hollow non structural bones to greatly reduce weight as part of their complex system of air sacs in their highly developed unidirectional respiratory system, the long necks supporting large feeding envelopes relative to the amount of energy extended to acquire that food, the reacquisition of a quadrupedal stance and some other stuff related to ligaments and bones that I don't remember the specifics of. OH and the use of r selection rather than the k selection favored by other large dinosaurs or mammals. Sauropod parenting equaled dig a hole with the digging claw on their hind legs then lay hundreds of tiny eggs and finish by reburying hole. As long as a few lived long enough to join the herd someday that was their parenting. Other animals even other dinosaurs just lacked that suite of adaptations and thus when the sauropods were wiped out 66 million years ago their niches have remained ever vacant as no other group of animals has developed the suite of traits needed to occupy those niches. The consequence of this is when large species are wiped out it can take a long while to refill those niches which can have evolutionary cascades. Going back to the Sauropod example the lack of parental care and the apparent ubiquity of young relatively helpless baby sauropods being high enough to in many places lead to their fragmentary remains serving as index fossils leads me to wonder if their extinction might not be the reason the same kinds of giant hypercarnivores haven't evolved to fill the niches left vacant by the KPg extinction. We are only really starting to become aware of the effects our wiping out of megafauna has had on modern ecosystems as well as the role human induced ecological changes mostly due to our use of fire and slash and burn agriculture when arriving in new previously isolated continents particularly Sahul(Greater Australia) and the Americas had on the indigenous megafauna. The best well documented example of human impacts is of course New Zealand due to the geographical isolation(imposed by ocean currents and the likes) having kept the land free of humans until the arrival of the Maori between the 13th and 14th centuries, the Moa went in the course of no more than a few hundred years from abundant and diverse to extinct.

[@bkjeong4302]

Giant animals are basically inevitable (even though they’re more vulnerable to abiotic factors later on) for one simple reason; it provides massive short-term competitive advantages, advantages that cannot be overcome by becoming “faster, smarter, social, better overall” like many people assume.

[@Ezullof]

I mean, we are the living proof that "giant animals" aren't necessarily an efficient strategy in all circumstances. Many people assume that humans will vanish soon, but what if they don't? What if the evolution of species like us makes giant animals much more rare? In the end this is just the old clash between a cyclical concept of time (in this case: periods of evolution of animals into giant animals alternate with mass extinctions, forever) and a more linear concept of time (maybe these cycles don't go on forever, or maybe if you look more closely, they aren't actual identical cycles). And all this is just another way to ask the question: are human unique in the history of Earth? Are we just another of these phenomena that cause mass extinctions, or are we something else?

[@huldu]

Maybe we'll go down this path a few millions years from now. We'll all be 3 meter tall, giant balloon tits and genitalia the size of an entire leg. Terrifying future. I'm just kidding if anything I suspect humans to perhaps even get smaller over time as we do so little physical activities(barely going to the gym twice a week for the "average" person does not count). Perhaps colonies on other planets will have very different results. In the end maybe we'll just stay very diverse unless something drastic happen and we start selective breeding for specific traits. That does not sound like a good future.

[@TheFanatical1]

​@@Ezullof The human strategy is not efficient by any reasonable metric: the reason humans are so successful is because we can exploit resources that nobody else could exploit, and those resources are in such fantastical abundance that the inefficiency of our exploitation doesn't matter (I mean, it will never matter, as there aren't really any other ways to exploit the resources, but we are not an efficient species at doing anything except possibly long distance running). We win because we can do anything inefficiently, not because we can do anything efficienly. We make species bigger than us rare because humans are uniquely good at specicide, not because being bigger than us isn't a huge evolutionary advantage in every sort of meaningful sense. Even among humans, the advantages (socially and physically) of being tall is signficant. You should not plan for global catastrophes when you're trying to do evolution, that's never going to be a good bet.

[@bkjeong4302]

@@Ezullof Humans did do a number on megafauna, but humans did so mostly by outright killing and destroying megafauna and the resources they need rather than by outcompeting them, and humans are obviously not comparable to any other animal to have existed in how much of an impact a single species can have on other species.

[@erickellar5867]

@@Ezullof humans no longer have selective pressure to push us to evolve more. If anything we will devolve or evolve in completely different or unique paths but those paths would likely push us to get even bigger and better brains at the cost of a large quantity of our physical prowess. So sure our potential future selves might be smarter but if we lose the infrastructure that makes use of our brain we become pretty useless and thus would go extinct. Just a theory of mine definitely not facts and I am no expert just fun guesses

[@jamesbates5901]

PBS Eons is RAD and so COOL. Well DONE to EVERYONE in the team

[@mack7207]

6:37 I just love hearing Americans/Canadians say Niche properly 😍

[@aureaphilos]

I can't help but wonder if Human Selection Bias plays a role in why there are so many examples of grand or mega fauna versus smaller species. Which fossil will generally 1) receive more media publicity, 2) garner more funding, 3) gain more celebrity for the sponsoring institution, 4) potentially result in more papers being published in journals?? From a marketing perspective, bigger is always better.

[@darcieclements4880]

also just fossilization in general favors really big animals because scavengers move them less and weathering damages than less. Like when you get into things that are smaller than the size of say a chicken, the bones tend to be really badly scattered and fragmented and they'll just be a bajillion of them all in one giant mass because they got like washed there in a river. Good luck sorting that into something sensible. When you get into smaller animals most of those fossils are defined by their teeth because we rarely actually find enough of a skeleton to be able to put it together into a singular animal. The only exception are basically fossorial or aquatic species because they get buried right away when they die. We also have a bias towards the ancestors and relatives of mammals because their skulls hold together better so we get the complete skull more often for them even when they're small.

[@TheFanatical1]

The result is much more easily explained via selection that occurs before the fossil even exists: small things do not fossilise nearly as well as big things, and so we expect to see big things over-represented in the fossile record. Certainly individual scientists might enjoy big fossils, and big fossils might capture the popular imagination, but I imagine that the scarcity of smaller fossils would make the research on them academically very interesting.

[@ac.creations]

Big thing last longer in the dirt, more likely to undergo fossilization, more likely to be found.

[@windhelmguard5295]

@@TheFanatical1 it's 100% fossilisation bias, especially considering that, while people love big and awesome, we also tend to like smol and cute so it should balance out. small animals tend to get crushed, swallowed whole and so on. also fossilisation occurs primarily where sedimentation occurs, sedimentation usually also implies the presence of large amounts of water, flooding and deposition of fertile soil, which would result in abundance of resources, which is where larger species tend to thrive. then you have the issue of needing to ask the question of whether a fossil of a small animal is actually of a small species, or a just a juvenile member of a larger one, which is not always an easy question to answer and one that i think we tend to get wrong fairly often. for example you're probably not likely to find fossils of a sand dessert dwelling species since the bones would very quickly be ground to dust by the harsh environment.

[@gergsmail01]

Easier to find too

[@Fantasygod930]

It's interesting that Back when paleontology was in its infancy People thought evolution was linear But that is not the case It's more like a web of different Traits Also interesting people thought that nature was survival the fittest and I guess there's some truth in that but it's more of Being able to survive in your environment

[@nealjroberts4050]

"Survival of the least unfit" doesn't have quite the same ring!

[@Epupify]

Survival of the fittest is what's actually related to evolution theory, what you explained at the end of your comment; what most people wrongly understand it as is 'survival of the strongest'.

[@spindash64]

@@Epupify More specifically, people forget that it's a simple pass/fail course, no real grading system. It doesn't distinguish between being stupidly clever and stupidly lucky. It's just that, normally, luck can't last forever...

[@widodoakrom3938]

Bigger than means required more resources to survived

[@GreenPoint_one]

Yes but per cm³ less food the bigger you get. Thumb small creatures must eat their whole body weight per day

[@lyrimetacurl0]

More needed per life form but much less per unit mass of flesh.

[@GreenPoint_one]

@@lyrimetacurl0 100 shrews eat less than 1 rhino, probably

[@joshuafernandes6684]

Small animals usually require much more food relative to their body size, at least homeothermic ones.

[@josephrion3514]

Which along with no predators is why island dwarfism occurs. Other factors exist.

[@carbon_no6]

Thunderbeasts sounds like a very low budget 80s cartoon.

[@joshuafernandes6684]

I don't think the question "Are giant animals inevitable?" has been answered. In a way, it could be said that as long as the enviroment could susttain large sizes, some lineages will fill that niches. Bigger is a lot worse in drastic enviroment changes tought, as we see in all massive extinctions, but after that we always see lineages incrising in size. What lineages will do better big than small is a matter of the historical circustances of their genetic pool and enviroment.

[@196cupcake]

"Bigger is a lot worse in drastic environment changes" exactly.

[@Telleryn]

yeah, being big is great so long as you have the resources to support that body mass, the moment there's a food shortage you're the first on the extinction list

[@196cupcake]

@@Telleryn It's the same with navigating a career path. When you're the expert on a specific, critical task, then you are practically un-fire-able. The generalist who can do most things, but none of them particularly well, is more likely to get fired when a company needs to downsize. On the other end, the nature of business changes over time, and if you specialize in one little thing, and then that one thing is no longer needed, you can quickly find yourself unemployed.

[@jacquesbaker1557]

One interesting exception to this rule is how Modern American Bison shrank as they evolved from their direct ancestor the Stepp Bison at the end of the last ice age shortly before the Stepp Bison became extinct.

[@MossyMozart]

@jacquesbaker1557 - The big predators were also extinct. Therefore a reduced need for being too-big-to-take-down. And if humans were really such an Ice Age factor, then, as a pantry strategy, they would target the biggest bison to hunt leaving the smaller ones to reproduce. This is happening in Africa today due to pressure from ivory poachers who want enormous tusks to sell on the black market. Elephants are producing smaller ones, these days overall, as smaller tuskers are left to reproduce. I think.

[@naamadossantossilva4736]

That can be blamed on indian hunters.

[@jacquesbaker1557]

Yea but white settlers were far worse and almost caused the entire bison genus to go extinct, before they decided to keep the two existing species as zoo animals. The American Bison dropped to fewer than 1000 animals and the European Bison dropped to less than 50 animals. @@naamadossantossilva4736 .

[@vaszgul736]

9:40 -othere actually means beast! It's this channel that inspired me to put terms like that in a fantasy world building project I'm making.

[@callindrill]

Thunder, Thunder, Thunder Beast!

[@nealjroberts4050]

I couldn't locate anything called brontofelis alas.

[@ufopsi]

“Thundercats are on the move…”

[@ecurewitz]

AaaaaAAAAAaaaaAAAAAAHH. THUNDER!

[@RSMoreno]

Hoooooooooooo

[@sandrareedy3420]

That blooper... I was right there with you, Blake!

[@veggieboyultimate]

I want to see a video about the macro raptorial whales, they were such a fierce group.

[@mauricewilliams1229]

The Brontosaurus, whose name means "thunder lizard" in Greek, is one of the most famous dinosaurs of all.

[@Goatcha_M]

Was such an awesome name. It's a crying shame that its now considered to have never existed. Apparently it was one of the many faked reconstructions of the early twentieth century where for the sake of fame and funding. Ironically the actual animal was the Apatosaurus which means deceptive lizard. Be nice if we could swap the two names around.

[@gaz-atolla7519]

​@Goatcha_M a 2015 study by Tschopp, Mateus and Benson classified Brontosaurus as its own distinct species within Apatosaurinae, although this is not universally accepted

[@Goatcha_M]

@@gaz-atolla7519 I don't see how that can happen. Marsh, the palaeontologist who named the creature admitted that he put the skull of a completely different animal on the body of another.

[@mho...]

#neverforget Dinosaur stands for "monsterous Lizard" after all! and if they where all gecko size, that name would never have stuck xD

[@Oneg321]

@@Goatcha_MThe type specimen for Brontosaurus excelsus (YPM 1980) is fairly complete, albeit headless. You don’t necessarily need the full skeleton to compare specimens suspected of being different genera/species. These calls have been made before with less material discovered.

[@brinleythei-rath2992]

Glad to finally see some brontothere content. One of my favorite groups.

[@joseguerreiro5943]

They look so cool

[@josephdonais4778]

"Change is the only constant", I like that.

[@AifDaimon]

First time a new Eons video is uploaded JUST after I end work at 6pm

[@lorefreak94]

6am here. Also just got out of work🙂

[@claymonsterpottery]

Your giggles are the best. First time I’ve laughed all week. Thank you. 😂❤

[@FrancisKnepper]

Bigger is *often* better; size is a big factor for a herbivore having to eat more to get its protein or a suspension feeder filtering massive volumes of seawater. Then, periodically, the climate hiccups, and suddenly the smaller critters with far smaller food demands have a much bigger advantage. Rinse and repeat.

[@daphneloose5880]

thunder beasts are really cool looking. they look like rhinos with strange horns.

[@bradacker8028]

I truly enjoy y'all's presentations. Thank you

[@AynneMorison]

Blake turned into an 11 year old for a couple minutes - but then lots of us probably did.🤣🤣

[@FrançoisJohnson-r6e]

always fascinated by the use of the word "mere" when talking about 20 million years lol

[@JClouseauB]

A guess game instead of "jokes" made me really happy. After some googling I found interesting information I would never start to seek for. Thanks!

[@realshaoran4514]

"... is that change is the only constant". This is a very nice sentence which seems to contradict itself but in that context, it make so much sense.

[@ilovetofu2016]

Blake looks great!

[@jasonGamesMaster]

Makes sense. Natural selection is a short term game. Bigger size gives them an advantage in most kinds of competition, but the larger they are the harder it is to adapt to changes. If there was an actual design or a non-random plan that was somehow guiding the processes some form of moderation would be much more generally successful overall

[@MaddoxLightning]

Brontosaurus. Also… again, I want to thank you all for acknowledging the native lands these fossils were found on. Nia’wen.

[@marcpeterson1092]

6:02 To me, this seems like it doesn't disprove Cope's rule. So species appear randomly, but natural selection pushes toward larger animals. That is just the mechanism by which Cope's rule works.

[@spiritlessmonkey]

I've found it helps to think of evolutionary changes in regard to not just life forms, but also any processes like changing fashions, politics, use of technology, etc., as the branching arms of a slime mold. Even the breathlike ebb and flows can relate to the left and right (extremists) steps that propels life forward.

[@Miamcoline]

These types of revisits of theories using new techniques are so important. Well done and good episode!

[@bakoyma]

Best bloopers yet ;-D Love these videos

[@darthmortus5702]

I've noticed a sort of related rule I've dubbed the size trap. To me it also seems that evolving towards size is better, all other things being equal. However the giants of their era seem to invariably die off when mass extinctions hit. It seems to be a pathway that evolution favors but which is inevitably a dead end, which is the trap I mentioned Now this video would seem to disprove the premise, and I'd never argue that being smaller isn't better sometimes. But as I said if all other things are equal being bigger is better, for all the reasons listed in the video like defense, dominance and so on. And it is also a fact that smaller, more generalist critters tend to be ones that survive mass extinctions simply on account of needing less food and finding it more easily. I am really curious if anyone who is specialized in paleontology has heard a similar idea expressed before.

[@spindash64]

Alternatively, things DO get bigger on a very broad span of time, but not because big is inherently better, but simply because, in the words of a wish lungfish: "this niche empty. FEET". Big niches are less stable in times of great disaster, but there's also more room for life forms to get bigger than the current largest at any given point in history than to get _smaller_ than the smallest at any given point in history. You can't really have an animal with half of a cell, but there tend to be enough loopholes around square cube law to give ways to expand in that direction, especially BECAUSE those organisms often get hit by the reset button, leaving space for a new group of giants

[@darthmortus5702]

@@spindash64 That's a fair point, given how the giants almost always die out in times of crisis then growing to fill that void is inevitable. Still my point would stand, and their time tends to be limited. There are no descendants of brontosaurus or t-rex, and likely there won't be any of the blue whales. Though admittedly that will likely be at least partly our fault.

[@equesdeventusoccasus]

Brontosaurus or as it was later called the apatosaurus was my introduction to dinosaurs, many many long years ago when the earth was still cooling.

[@Kr4zYm0f0]

its been brontosaurus for years again

[@equesdeventusoccasus]

@@Kr4zYm0f0 now if we can just get Pluto re-established as a planet.

[@MossyMozart]

@@equesdeventusoccasus - Yes! It even has geological activity and an atmosphere.

[@Kr4zYm0f0]

@@equesdeventusoccasus well its a dwarf planet. (:

[@kahnabull1694]

John Davison Ng has been an Eontologist for so long at this point. Since the beginning. I feel like he is just part of the show. I want to know who he is.

[@kahnabull1694]

Mysterious benefactor vibes.

[@spnyp33]

"... a span of a _mere_ 20 million years..." That's how you know you're on Eons ;-)

[@orlevzach]

Great episode, awesome channel. Thank you!

[@nyves104]

I'm so excited for the new calendar, I absolutely love the one for this year 💜💜💜💜

[@PunkRaider]

Love the new hairstyle

[@Grant_S_M]

PBS Eons is one of the best things going. 🖖

[@supermanifolds]

Can you please make a version of the calendar where the week starts on Monday as it does in the majority of the world?

[@jamesrogers1391]

SPEAKING of getting BIGGER, BLAKE is looking THICK, SOLID, and TIGHT. THANKS for the MOTIVATION!

[@lassehauerwaas3078]

Why is it that big animals are described making a lot of noise when they walk? "The ground is trembling", T-rex making the water move in a glass etc. An African elephant can walk right behind you without you noticing anything. Basically big animals don't stomp unless they are escaping a predator or running in a group.

[@jobyd2000]

Blake's giggle would melt a heart of stone.

[@SunnyNight]

Could you guys possibly do a short video like this but on the phenomenon of island ecosystems affecting animal size evolution? Like some islands have very small creatures while others have huge ones (like Kodiak Bears in Alaska).

[@AndrewTBP]

They already have videos on island gigantism and dwarfism.

[@germanomagnone]

4:45 I can't understand why in some new reconstructions of the embolotherium they have a "big nose" instead of a snout like rhinos

[@CritterKeeper01]

"Changes aren't inevitable, but change is."

[@koopstacochran]

So basically evolution hedges it’s bets against survival of environment by evolving creatures in both size directions.

[@SunshineMoon_._]

I get so excited when you post. You have taught me more that school ever has 😭

[@astromenuisix7346]

Well, the first thing that I learned while doing my Bachelor in ecology is that being small is way more costly for an individual then being big. You see, when you are small, you have way less surface in your digestive system to absorb nutrients. But, you need way more energy to survive since you have way more cells/volume of yourself than if you were bigger. So in order to be efficient when you are small, you have eat, pretty much, all the time. 😅 Plus, if you are mammal, you loose your heat more easily because of the same reasons explained precedently. On the opposite side of the spectrum, being bigger (well on land) means ( if I remember correctly) that you need to have more bone mass in order to support your weight and you are less efficient to get your nutrients to every cells in your body. But, you have more place for a bigger brain, way more energy absorption and other benefits that I forgot/not sure. So, yeah, being bigger is, most of the time, better then being small.

[@tchad49]

To the extent that Cope's Rule has any truth to it, the one obvious evolutionary pressure no one ever considers is this: Lifespan scales with body size. The bigger you are, the longer you live. The longer you live, the more offspring you will be around to have. This advantage is invisible (lifespan) so gets ignored.

[@discojelly]

Aka: the Shovel Tusk! One of my faves from first learning about it in my childhood!

[@Frezzed]

Love the new background music

[@jamesdriscoll_tmp1515]

I think evolution favors the taking advantage of unexploited resources. If that's a matter of size, so be it.

[@358itachi]

I think the problem with paleontologists finding bigger animals more is the inherent nature of fossilization itself. Smaller animals don't fossilize well for many reasons from being easy meals to scavengers compared larger dead bodies, faster decomposition and smaller skeletal frame prone to dispersal of remains etc. Also smaller fossils are difficult differentiate from the surrounding rock and debris and may go unnoticed during excavation.

[@eljanrimsa5843]

That's true but that wouldn't explain why older fossils are smaller.

[@craigsurbrook5702]

Only if there is enough food. Any food shortage, the larger species inevitably quickly die off.

[@webheadwonder9597]

It would be cool if you guys covered how scientists determine when animal physiology is due to convergent evolution. I think it was somewhat covered during the crabs video. But it would be interesting to hear about the process

[@TerraStory225MYA]

Thanks for providing such easily accessible science education to so many people!

[@yanjulio]

I mean... you gotta love Blake, am I right?

[@m4r14j]

RIP those jokes at the end 😢 I always loved them personally wholesome good fun

[@mellissadalby1402]

Hi Blake, I ordered my calendar, thanks!

[@ajg0075]

Great video, I always love learning about prehistoric creatures, from their evolution, diversification and to their extinction. Maybe you can do more on the evolution of animal lineages like these: Creodonts, Mesonychids, Percrocutidae, Desmostylians, Xenarthrans, Dinoceratans, Oreodonts, Protoceratids, Astrapotheres, Proboscidea, Ceratomorpha and Megaraptorans. Not to mention specific creatures and their evolutionary relationship with other animals like Andrewsarchus and the Pronghorn.

[@bkjeong4302]

They did “creodonts” and horribly misrepresented their rise and fall by playing into oft-repeated but false claims about their “inferiority” and “inefficiency” compared to the oh-so-evolved carnivorans.

[@Ahrim565]

wow what an amazing video. so much cool facts! love you guys

[@stephenbesley3177]

I tend to think it's a far more complicated issue. I can think of many reasons why size difference might impact evolution and any might or might not be a factor depending on species and circumstances.

[@joshuafernandes6684]

Yeah. It also have a lot of physical issues involved as an animal grow or shrink. The fact that after mass exctintions size incrise always happen in some lineages should at least say that if some lineages could take that niche, they will take it.

[@MrYougotcaught]

Speaking of size...Blake 👀

[@windlessoriginals1150]

Thank you

[@aarongillett1449]

Props for recognizing the First Nations.

[@trevinbeattie4888]

I had an advantage on the trivia question: RobWords put out a video on the meanings behind dinosaur names last Saturday.

[@charliekezza]

"honey I shrunk the life" 😂😂😂❤❤❤

[@lordofthefreeks]

This is lovely! I wish it would have acknowledged the breakthrough research of Tyler Alyson and Ian Miller and their vertebrate paleontology research which changed the game with regards to science “after the asteroid!”

[@odizzido]

Good stuff :) I really like you guys.

[@Pottery4Life]

Thank you.

[@dziban303]

I dunno about brontotheres but Blake's certainly getting swole

[@Goatcha_M]

Could also point out other trends like Island Dwarfism. Ultimately its all about food.

[@FeeshUnofficial]

Honestly not even. It's way more complex than just food. It's opportunity. It's environment. It's open niches

[@marcoghiotti7153]

Change is the only constant indeed!

[@dimithryyy]

Blake is baaaack😊

[@datpolakmike]

If the niche is open, then yes. Life diverges to fill niches, so as long as being big as heck is a valid niche, something will fill it

[@danwylie-sears1134]

My impression before listening: There are advantages and disadvantages to being different sizes. Species with smaller individuals can more readily have enough individuals to have a viable population in a small patch of habitat, or make it through a time when there's not much food. Species with larger individuals can avoid predation more effectively. And so on. Mass extinctions tend to leave empty niches for large animals, so the trend within lineages should generally be toward larger individuals.

[@Goku17yen]

man, i love this channel

[@xandrewvondiue522]

Mind-blowing. This is epic

[@MossyMozart]

@xandrewvondiue522 - Or "epoch". ^_^