Why Were Prehistoric Animals Bigger Than Today’s Animals?

Why Were Prehistoric Animals Bigger Than Today’s Animals?

Evolution is a slow but sure process that, in most instances, takes millions of years before any serious notable changes can be noticed. One question that has puzzled many people is, why were animals so big in the past?
For a long time, environmental factors such as higher oxygen content in the air and greater land masses were thought to contribute to their large size. To understand how environmental conditions may have contributed to the evolution of larger and more complex animals in prehistoric times, it is important to consider the types of habitat that would have been common during this era.
In particular, these organisms likely lived in warm, moist climates, where food was abundant, and there was limited competition for resources. Given these conditions, natural selection may have favored traits such as increased body size over features such as heightened agility or speed, as bigger animals were better equipped to survive and thrive in this environment.

#Prehistoric #Animals #Dinosaur

[pitbullthedog]

Sadly it feels like animals are getting smaller and smaller . Our largest land carnivores like bears, tigers, and lions are all dying out. Even elephants are not doing good as they used to. Rhinos are endangered

[jordanwatson]

Roaches the size of cats?!? I would die

[andrewstrongman]

I expected this video would trot out various arguments in support of the premise. Instead, I found it to be very well researched and well presented. The size attained by animals is dependent on climate and their environment. Human predation has resulted in larger species becoming smaller for a couple of reasons: The largest animals rarely live long enough to produce significant numbers of offspring, so their genes are removed from the pool. Some species may select smaller mates due to their having a better chance of survival. Another result of human hunting activities has been the reduction of antlers in some deer species, and most obviously, the reduction in tusk size of male elephants. That's probably the best example we have of rapid evolution.

A phenomena not mentioned is the dwarfism of large mammals when they are restricted to small islands. Notable examples are elephants, hippos, and tigers.

[legendarynature]

Nice video. Another reason why is because we are in the middle of the 6th mass extinction and the biggest animals are usually the first to go during these times

[tonyalove]

Please make a video showing you Komodo dragons survive in North America

[FGUGZIN]

I have to say this is my favorite video of this channel so far

[benmcreynolds]

The most important aspect is not that the upper land animals were around elephant weight and size. Its the fact that small species of all kinds were larger and much More diverse and just all around all things were more massive. Just look at ice age creatures but then the era right around early primate evolution towards humans it seemed like so much changed in regards to the fauna and flora.

[Prismalpink]

Because of lush lands and an abundance of water and food. There was always something to eat, and a lot of land to frolick in.

It’s like how people get taller and bigger as we progress in time due to an abundance of foods.

[kinglewisjtl]

Amazing content, I love how you break things down and weave it together in a temporal linear sequence while interjecting definitions of needed vocabulary and social psychology in-between the evolutionary story of size changes of the largest species explicating the factors of the environment within their particular epoch, and juxtapose their size with todays largest land and marine animals.

Saying there is not enough room or time for the largest animals to grow today is sad- the truth is sadder still, we've hunted them to extinction- succumbing to mindless greed and sport.

[ivanmartinez]

So basically bigger was better back then, so it became a competition for size

[tylersortia]

Next video you should talk about the evolution of whales of the whale that has walked on land.

[isaacbruner]

Triceratops was not a hadrosaur, but overall this was a pretty good video

[ILaunchNukes]

Could Jurassic World's dinosaurs survive in the real world? (Our universe)

[indyreno]

There's also the extinct genus of carnivoran known as †Chapalmalania, a large relative of the coatis that lived in South America, both Chapalmalania and coatis are classified within the family Nasuidae, which also includes the olingos, olinguito, and kinkajou, this family also classifies other South American genera of carnivorans, their ancestors ended up in South America, not by the great American interchange, instead by oceanic dispersal, these other extinct genera of nasuids include †Tetraprothomo, †Parahyaenodon, †Pachynasua, †Brachynasua, †Amphinasua, and †Cynonasua (sometimes Cyonasua), all of which are also native to South America, Nasuidae first appeared during the Miocene in South America, where these carnivorans still coexisted with another predatory mammalian group known as the sparassodonts, an extinct group of mammals closely related to marsupials, the nasuids are the first carnivorans to originate from South America, Nasuidae contains only four extant genera, Potos (Kinkajou Lineage), Bassaricyon (Olingos and Olinguito), Nasua (Common Coatis), and Nasuella (Mountain Coatis) and many extinct genera such as †Tetraprothomo, †Parahyaenodon, †Pachynasua, †Brachynasua, †Amphinasua, †Cynonasua (sometimes Cyonasua), and †Chapalmalania, the Nasuidae family is found out to be most closely related to the family Ailuridae (Lesser Pandas).

[NotLtrex]

More oxygen didn't make them grow big, there was only about 35% oxygen.

[no_lft_shft]

It's 2am and this is what I'm doing instead of sleeping. Why am I like this. Do a video on that.

[Theonetrueerenyeager]

It’s a common misconception that extinct animals are much bigger than extant animals, and while that’s somewhat true, animals like mammals have maintained steady sizes between that of cattle and elephants. Animals like indricotherium and the straight tusked elephant were the exception, not the rule.

[GregoryShtevensh]

People don't understand the sheer amount of time spanned for all animals. Dinosaurs lived for 160 million years! SO while some were huge, It doesn't really mean anything when comparing it to today.
In fact today, we have the largest animal EVER - The blue Whale.
There has also never been a known animal faster on land than the cheetah, or an animal with as much intelligence or as flexible forelimbs as humans today.

[michaelransom]

While i applaud the attempt, there are a number of errors or misrepresentations, at least in the first half. The last half was on the money, overall not bad, the core messages were accurate and well presented. the only corrections would be the parts about warm weather correlating with large body size, this is only true for cold blooded animals such as crocs or snakes, and yes, warm conditions during the paleocene–eocene thermal maximum, around 55 million years ago, led to some MASSIVE reptiles, turtles the size of cars, and creatures like the nearly 50 foot long snake Titanoboa. But for mammals, it had the opposite effect.

Mammals only started becoming truly massive as global temperatures decreased, with the largest mammals generally existing during ice ages.
Next... The carbon cycle between large living animals and plant vegetation is a small contributor to the oxygen/CO2 balance of the atmosphere. WHen excreted as methane the emissions of large animals can have some effect, but this is generally dwarfed by the effects of decomposers, volcanic activity, rock weathering, etc..
SInce the massive spike during the carboniferous, 300 million years ago, when oxygen levels reached 35%, and the subsequent minimum around 200 million years ago, when the oxygen content fell to around 12% (rise of dinosaurs and their unique respiratory system) the level of oxygen has been on a relatively slow and steady climb up to todays roughly 21%.

So outside of the effect on insect size that we saw during the carboniferous, oxygen levels were not a major contributing factor to the size of animals in the past. and the reason it was so high during the carboniferous is because of the evolution of cellulose and lignin in the trees of the time. these could not be broken down by the decomposers that existed at the time. It wasn't until the evolution of cellulase that fungi were able to break this molecule down and restore the balance.

anyway.. i know that these are superficial points, and that the overall message was that, for the most part, there were large and small animals throughout history, and other than some outliers, there isn't much difference between the size of animals today and those throughout history. (well maybe not "today" but in this most recent geological epoch, right before humans started dominating the planet and wiping out all the megafauna)

[stavrospartheniou]

"Why Were Prehistoric Animals Bigger Than Today’s Animals?" Answer: Cause they don't make 'em like they used to.