Why were prehistoric animals so big?

Why is it that prehistoric animals seemed to be so much bigger than they are today? Well, let's find out....

(The above is an affiliate link, meaning I make a small commission on each purchase at no extra cost to you)

Be sure to like, comment and subscribe!

Also don't forget Dino-gen is on Instagram, Facebook and Tiktok

All pictures are either licensed under the Creative Commons Attribution 2.0, 3.0 or 4.0 International license or come under the fair use policy

Image credit:

Thumbnail art belongs to PaleoEquii
Carboniferous forest Illustration by Mary Parrish © Smithsonian Institution
Carboniferous illustration 2 by John Weinstein
Haast’s eagle: John Megahan / PLOS Biology 2005

[cjalexanderjr]

One theory I heard why some dinosaurs were so big compared to mammals is that dinosaurs laid eggs. Mammals have to use energy during gestation for their unborn offspring. I don’t know if this theory holds water, but kind of fits with the energy usage you talk about in this video. 🦕

[tessie]

I know it's not even that big but for it's time period i absolutely love Anomalocaris. Such a cool creature.

[thenarwhal]

I have a different opinion regarding temperature. I would say the warmth had little to do with it, since dinosaurs were probably endothermic and therefor Bergmann's rule should apply. Meaning that with colder temperatures larger body sizes would ensure. As seen for example in Blue whale populations. Closer to the equator in the Indian Ocean the B. m. indica is considerably smaller at 24m (79ft) that the Antarctic blue whale at 30m (98ft).

[MrTylerStricker]

Love your videos & channel! Looking forward to watching your audience grow! Thank you!

[Prometheus_Bound]

I would have loved if you'd talked about large terrestrial mammals and why we don't have them any more.

[andrewcrowe]

Nice video! I always wondered why dinosaurs were so big. BTW, Higher heat leading to bigger bodies is not so intuitive - because one strategy to retain heat is to get bigger. I think you mentioned that with higher heat more calories can be dedicated to other activities besides keeping warm?

[enternalinferno]

Another great video, looking forward for more to come!

[redrex]

Awesome video! Topic was intriguing and well presented.

[thomasgumersell]

A very interesting video on the various sizes of Dinosaurs. 💪🏻🙏🏻✨

[lachlanmacarthur]

Also there was only relatively recent megafauna extinction. Not many large land mammals remain. Here in Australia People would have met a lot of large mammals and reptiles but now nothing is bigger than roos. Well excited for crocodiles.

[foxmccloudizsexy]

Why am I looking at your eye motions half the time?

[dragonfox.]

But we don't know how big Livyaten was, do we?

[hollyodii]

Today my fav super-sized animal of prehistory is the Dire Wolf! Patagotitan is great too!

[richardwheeler]

Hey, we have the blue whale, the biggest animal that ever lived.

[RayRay-dvxg]

I like that content. But the heat thing is wrong. Sure, all living beings need some heat. But animals become larger the colder it gets, not the other way around, because they produce a lot of heat. Large animals need to get rid of heat in a hot enviroment. Polar bears can overheat in the arctic.

[rollotomasislawyer]

Question: During the Carboniferous period, if there was only 1/3 more oxygen, how did arthropods get to be hundreds of time larger then today?

[goliathsparrow]

Giant pterosaurs are my favourite totally bizarre

[firegator]

the real question is not why animals were so big but why animals today are staying small and i think nowdays its very obvious to see that we get in their way, destroying habitats and getting food sources is a big reason why animals will not get that giant as some of their prehistoric relatives were, best example is the arctic where the largest terrestrial carnivore, the polar bear exists and the environment changes from climate change have affected their hunting dramatically and re shaped their environment so hunting the prey they are specialized to such as seals is very difficult and thats why very rarely a hunt of an adult seal is very rarely a success in the past the amount of ice also helped some seals, some species created small shelters to hide their babies in but now with climate change the ice got flatter and more plain leaving their babies in sight and in turn polar bears just dont have as easy time ambushing their prey because of these ice formations gone
this is just one example why as long as humans exist animals not only wont get bigger but some species might also benefit from evolving to be even smaller than they are today, some fish we prey upon already decrease in size since fishermen catch the biggest individuals and let the smaller ones go so natural selection forces them to stay smaller than before, but many changes are very fast for evolution so animals have no time to adapt

and my favourite group of animals that ever lived are probably the sauropod dinosaurs, they are very awesome group that got small species and giant ones, weird ones with long spikes on the neck, ones that have tails that account for half of their total length, ones that have very long necks and ones that have very short ones....specifically my favourite though is camarasaurus itself is not that weird but it has very interesting discoveries, other than the fact that we have it mostly complete and we know very well what it looks like we also have more amazing discoveries from it like eggs that are clutched together in a way that shows that they did not care for their young and they lived by themselves from birth and also a debatable discovery that might be keratinized beak or hard lips tissue concealing their mouth which is very weird and for now still kinda speculative, its also the most common sauropod found in it's habitat, the morrison formation

[jamxx]

there were 444 views when i clicked this video and i was tempted to not ruin the perfect number but i love this channel ill be the 445th view hehe

[SubbyHuskyV]

Heyyyy a bit late on this video but I had a question what is the likelihood a human species was similar to giants, and or could it of been a similar branch to us and more similar to monkeys?