One Of Earth’s Largest Mammals May Also Have Been One of The Dumbest

Written by Sarah Psaradelis
Published: October 18, 2022
© Charles R. Knight / public domain – License / Original
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Large with a small brain sounds strange right, but about 63 to 52 years ago during the late Paleocene to middle Eocene Period, a large browsing mammal known as the coryphodon roamed the earth. These creatures had a similar appearance to a modern-day rhinoceros, and they were one of the first giant genera of mammals that appeared after dinosaurs.

Now, the coryphodon might have an astonishing appearance with its oddly shaped head and small ears, but they didn’t offer much in terms of intelligence either. The coryphodon had one of the smallest brain-to-body ratios at the time, but although their brains were small, they were probably still intelligent according to science and what we know about similar animals today. So let’s learn about this large mammal with a small brain!

The Largest Land Animal at the Time  

Coryphodon was a large, heavy mammal that was similar to a hippo.

©Charles R. Knight / public domain – License

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The largest species in the coryphodon genus reached 8.2 feet in length with a height of 3.3 feet, weighing up to a ton, making them extremely large mammals at the time. Their size is comparable to an elephant, but their body structure resembles a hippo or a rhino.

Coryphodons were the world’s first-ever group of large browsing animals, and they are believed to be one of the largest land animals known as pantodonts at the time of their existence.

However, not all species of the coryphodon grew to such impressive sizes and could be described as the largest on earth at the time. Most of the species did not grow to be as large as the Coryphodon proterus, which was the largest of the four coryphodon species.

The C. proterus and C. lobatus grew the largest, while the C. eocaenus was the smallest at 750 pounds, and the C. radians at 1,500 pounds. Even though some species are smaller in size, their size is still quite large in comparison to other mammals at the time.

An Odd Appearance

Coryphodon was a heavy creature, and their movements were slow and sluggish. The coryphodon’s short and stumpy limbs didn’t allow them to run or move with speed, and their barrel-shaped bodies were built for slow, grazing behaviors. They had strong and prominent neck muscles and tusks that they likely used to uproot plants to eat, along with broad feet that helped stabilize their heavy weight. Their head had no horns or occipital region and its strong limbs helped to support the coryphodons heavy size.

Like other large browsing animals, the coryphodon didn’t need to have speed and the ability to run very fast. They didn’t have much to protect them from predators, as they had their tusks for eating, and their teeth weren’t made for hunting.

Small Brain to Body Ratio

The skull of a Coryphodon
The coryphodon had a very small brain with weighed only around 3.2 ounces, despite its large body size

©Jonathan Chen/Wikimedia Commons – License

The brain size usually increases in size as the animal grows, especially if the animal itself is very large. However, the coryphodons didn’t develop past a certain size, even though they were big. This is known as brain to body mass ratio, and it is used to indicate how intelligent an animal is, although this is usually inaccurate because scientists have discovered that is it not the size of your brain that is a direct indication of how intelligent you are.

Even with such a big body, they had a brain that scientists believe only weighed around 3.2 ounces. For such a large animal, you would expect its brain to be a bit larger than that, considering that a human’s brain weighs around the same, except our brains make up around 2% of our total body weight.

So, how could such a large animal have such a small brain? This is odd since it is typical for small mammals to have a small brain that is in proportion to their size. The coryphodon seemed to not follow the general rules, but this is not uncommon since the modern-day elephant has a comparatively small brain-to-body size.

Since elephants are so clever and regarded as intelligent mammals, it is unlikely that the size of the brain has anything to do with the animal’s intelligence. The size of the brain is measured in accordance with the animal or human body mass and the amount of space the brain takes up in the body. For example, a small animal like a mouse will have a much smaller brain than many other animals and humans, however, this doesn’t make them dumb.

Some of Earth’s largest animals have a small brain-to-body ratio, but they were not dumb, even though it is a misconception to believe that having a small brain automatically makes you less intelligent. Instead of the brain’s size being an indication of how smart an animal is, it is the neurons that make you smart. Certain neurons in the brain are responsible for cognitive function and abilities that make certain animals intelligent.

It has been found that large animals like the elephant have von Economo neurons in their frontal cortex, which is why these large animals with such a small brain-to-body ratio are so intelligent. The same theory can be applied to the coryphodon which is in the same position as the elephant as both have small brains and very large and heavy bodies.

Why do some Animals have a Small Brain?

A Coryphodon, an extinct mammal and pantodont
Although people assume that coryphodon was dumb, brain size is not reflective of intelligence

©Biodiversity Heritage Library/Flickr – License

Brain structure is more important than your brain’s size, and this is true for many intelligent animals. Since a human has a folded brain with a complicated cortex and von Economo neurons, we are seen as one of the most intelligent and mentally superior “animals” on earth.

The brain-to-body ratio for most mammals is around 1:180, and some of the most intelligent animals have the highest brain-to-body ratio. However, the size of the brain is not very important when it comes to whether the animal is intelligent, as it is rather the volume of the cerebral cortex that is there for cognitive processing along with certain neurons in your brain.

The cognitive ability of an animal is what helps indicate its intelligence, even though it is strange to think that an animal with such a small brain, but a large body could ever be smart. The brain is a fascinating organ, and each animal has a different level of cognitive ability.

It is unclear why some animals have a larger brain-to-body mass ratio than others, and it could be dependent on how the animal has evolved throughout millions of years. This proves that an animal’s evolution seems to not change the brain size ratio to the body mass of an animal or other biological organisms.

Does a Small Brain make you Dumb?

It is widely thought that anything with a small brain is automatically dumb. However, if this was true, then we would be calling some of Earth’s most intelligent animals dumb when they are not. Even though the coryphodons brain is not in proportion to their body mass, they were likely not dumb animals. Instead, if they were anything like the elephant, they were probably quite clever at the time.

Scientists cannot be sure as to the coryphodons habits that would make it intelligent, such as a great memory or specific cognitive abilities that show its intelligence, since these creatures went extinct millions of years ago. We can only go off the research we know today that proves that the size of your brain does not prove your intelligence or stupidity.

Another example of a known intelligent animal with a small brain is the blue whale, which has a very small brain that just doesn’t match its body weight. From big-bodied to small-brained animals like the blue whale and elephant, the coryphodon might not have been dumb and there is a possibility that they were quite intelligent, but we may never know.

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© Charles R. Knight / public domain – License / Original

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About the Author

I am a big animal lover that not only enjoys owning and getting to care for them, but also to write about them! I own many fish, along with shrimp, hamsters and a docile tarantula. Writing has become my passion and I am grateful to be able to write about the animals I love so dearly so that I can share my knowledge and expertise in the articles I write.

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