Why were prehistoric era animals so gigantic in comparison to animals from the “modern era”
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This is a misconception for the most part. The largest animals that have ever lived are alive today.
The absence or scarcity of certain types of animals and the availability of abundant resources created opportunities for certain species to evolve into massive sizes.
🦖- Firstly, let’s consider dinosaurs. These giants were able to grow to enormous sizes due to several factors.
For example, the earth’s climate during that time was generally warmer than it is today.
This warmer climate allowed for abundant plant growth, providing a vast food supply for herbivorous dinosaurs.
Plus, dinosaurs had a fascinating respiratory system that gave them an edge.
They had these amazing air sacs that extended into their bones, which actually made their skeletons lighter compared to the animals we know today.
This unique adaptation allowed dinosaurs to reach enormous sizes while still being able to move around and support their massive bodies.
👨🏼🔬- You know, when it comes to animals, their size isn’t just a random thing.
It’s actually shaped by a bunch of factors in evolution.
Now, when it comes to those huge prehistoric creatures, scientists suggest that these colossal sizes served as a defense mechanism against predators or helped them regulate their body temperature more efficiently.
So, size played a crucial role in their survival and overall well-being.
Nowadays, the sizes of animals we see are totally different, and it’s because of a whole new set of ecological stuff going on.
You see, our Earth’s ecosystems have been evolving and shifting for millions of years.
That means the environment has changed and the resources available are different too.
Plus, the animals we have now have evolved to fit into their own special ecological spots.
And guess what? Those niches don’t always call for big sizes like the ones the prehistoric animals had.
So, it’s all about adapting to the circumstances of today’s world.
This is a loaded question. The biggest animals to ever live are alive right now, they’re called blue whales.
Interestingly, there is a theory out there now about the lack of large apex animals. Many, many years in the past, like 150,000 years ago or something (I’m sure I’m wrong about the time) most habitats in the world had large apex animals. Basically the top of the food chain type animals. Not all meat eaters, but mostly them. Things like raptors the size of small planes, giant saber tooth animals, Australia had a land turtle the almost the size of a VW bug, there are many more examples of these that slip my mind.
The main theory is that there were some extinction level events, decades long droughts, volcanic activity, things along those lines. The thought is that the apex animals were so specialized that they couldn’t adapt.
In the past decade or so a new theory has started to come out, a bit of a controversial one. When researchers were looking at the fossil records they noticed that a lot of the large apex animals were dying out regionally, not world wide. If you consider large, elephant like animals, they were distributed relatively evenly across Europe, Asia, and North America. If it was a climate issue you would expect them to all die out around the same time, give or take a few hundred years. This would be the same for other apex animals with wide distribution.
The problem is, you don’t really see that. Most of the time you see these types of animals dying out around the same time as early humans started to show up in the area. We didn’t pop into the world all over. We probably started in Africa and slowly spread around the world in waves. When we would move into new areas we would encounter these large animals that hadn’t really developed any defenses against human pack hunting. And when you have a tribe to feed it’s easier to take down one large animal than a dozen smaller ones.
The time lines line up. North America had apex animals for the longest time because humans got here last, essentially.
Now yes, there were extinction events, there was the ice age, etc… but it’s almost too much of a coincidence that large land animals died out in regions around the time that our human ancestors moved into the neighborhood
The simplest answer: We ate all of them. Megafauna ( the gigantic animals like giant sloths and mammoths) consistently die off as soon as early man shows up in the places where they live, and there’s evidence of us hunting them. They were our favorite foods, and we ate them to death.
Part is that it’s easier to find big bones than small bones. In a million years it will be easier to find elephant bones that survive than little mouse bones, so it will make it seem like there was more elephant sized animals than mice even though we have both
The Rise of the Grasses. In north america after the last ice age there was a regime change in the type of plants which covered the ground. Mammoths like the ones that lived in San Jose, California 8 thousand years ago could not have survived on the native plants which exist here now because the caloric density per square mile isnt high enough to support these animals.
Because as humans took over and travelled to new places we exticted the largest animals first. Big animals have a lot of meat, are easy to spot, and can’t run away. We know this from archeology and from the histories of places like Australia. Big animals also suffer the most from habitat loss since they need more resources. This process is still happening. The large animals that are left are the most at risk of extinction from human activity. Look up “trophic levels” for more info.
we don’t actually have to go to prehistory to see a lot of different megafaunal species existed recently, we humans simply hunted them to extinction.
The problem is that you’re comparing at the very least MILLIONS of years to the last few thousand, that skews perception. Also which animals? We are talking MILLIONS of years here, so it kinda varies from time to time. Giant insects were due to higher oxygen levels on the atmosphere (they breath through their skin, it is not super efficient, so if the levels go down, their size thus consumption has to go down).
Ancient dinosaurs and those often misidentified as them, it is a case of it is +165 million years. You’re bound to find a handful of particularly extreme exceptional species along that time, many of which rose and died off/evolved off and they never co-existed. At any one time, it is hard to say they had drastically larger animals than we do. Yet, we often of them all together, as creatures living all at the same one time period, “the past”. And we often ignore that for every very large dinosaur, there was a crap ton small ones that would shit themselves near a polar bear. At least one source I saw listed the average as something between a rhino and an elephant, and that is from species from all over the timeline. Visual size is also deceiving, depends what the metric you use. A T-Rex was bigger than an African elephant by length and a bit too by height, but by mass (arguably the more important metric) they’re about the same iirc (at least same ball park). And of course, don’t forget our present day blue whale is the largest animal by mass to ever live, and by length still one of the largest on land or sea.
TL;DR: you’re comparing the extreme top sizes and amount of large species of just today with the extreme TOP sizes of at the very least millions of years combined – not a surprise the practically infinitely larger timeframe will have had more exceptional species.
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