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If dinosaurs had never gone extinct, what would they be like today?

author:Majer
If dinosaurs had never gone extinct, what would they be like today?

Sixty-six million years ago, an asteroid struck Earth with the power of 10 billion atomic bombs, changing the course of evolution.

The sky darkened and the plants stopped photosynthesis. Plants die, and then the animals that feed on them die. The food chain collapsed. More than 90% of species have disappeared. When the dust settled, all but a few birds were extinct.

But this catastrophic event made human evolution possible. Surviving mammals thrive, including those that will evolve into our small primitive primates.

Imagine that the asteroid missed and the dinosaur survived. Imagine highly evolved birds of prey planting their flags on the moon. Dinosaur scientists, discovering the theory of relativity, or discussing a hypothetical world that, incredibly, mammals took over the earth.

It sounds like bad science fiction, but it touches on some deep philosophical questions about evolution. Did humans just come here by chance, or was the evolution of users of smart tools inevitable?

Brains, tools, language, and large social groups make us the dominant species on Earth. There are 8 billion Homo sapiens on seven continents. By weight, there are more humans than all wild animals.

We have transformed half of the planet to feed ourselves. You could say that creatures like humans are bound to evolve.

In the 1980s, paleontologist Dale Russell proposed a thought experiment in which carnivorous dinosaurs evolved into intelligent tool users. This "dinosaur" has a large brain, thumbs facing each other, and walks upright.

If dinosaurs had never gone extinct, what would they be like today?

It's not impossible, but it's unlikely. The biology of animals limits the direction of their evolution. The starting point limits the endpoint.

If you drop out of college, you probably won't become a brain surgeon, lawyer, or NASA rocket scientist. But you may be an artist, actor, or entrepreneur. The path we walk in life opens some doors and closes others. The same is true in evolution.

If dinosaurs had never gone extinct, what would they be like today?

Consider the size of the dinosaur. Beginning in the Jurassic, sauropods, Brontosaurus and relatives evolved into giants weighing 30-50 tons, up to 30 meters long, ten times the length of elephants and as long as blue whales.

This occurred in several groups, including Diplodocidae, Brachiosauridae, Turiasauridae, Mamenchisauridae, and Titanosauridae.

This happens on different continents, at different times, in different climates, from deserts to tropical rainforests. But other dinosaurs living in these environments did not become supergiants.

The common denominator connecting these animals is that they are sauropods. Something about the anatomy of sauropods — lungs, hollow bones with high-strength weight-to-weight ratios, metabolism, or all that stuff — unleashed their evolutionary potential. It allows them to grow big in a way that land animals have never had or never had since.

Similarly, carnivorous dinosaurs repeatedly evolved huge, ten-meter, multi-ton predators. More than 100 million years ago, Draurosaurids, Allosauridsaures, Ankylosaurids, Neosauridae, and finally Tyrannosaurs evolved giant apex predators.

If dinosaurs had never gone extinct, what would they be like today?

The body of the dinosaur did a great job. The brain is not so big. Over time, dinosaurs did show a faint trend of increasing brain size. Jurassic dinosaurs such as Allosaurus, Stegosaurus and Brachiosaurus had small brains.

By the late Cretaceous, 80 million years later, Tyrannosaurus and duckbill had evolved larger brains. But despite its size, Tyrannosaurus rex's brain still weighed only 400 grams. The brain of a velociraptor weighs up to 15 grams. The average human brain weighs 1.3 kg.

Over time, dinosaurs did find their way into new niches. Small herbivores became more common and birds diversified. The long-legged form later evolved, suggesting an arms race between short-footed predators and prey.

The social life of dinosaurs seems to be getting more and more complicated. They began to live in groups and evolved elaborate horns to fight and display. However, dinosaurs seem to have mostly repeated themselves, evolving giant herbivores and carnivores with smaller brains.

There is little hint about 100 million years of dinosaur history, and if the asteroids hadn't intervened, they would have done anything completely different. We may still have those supergiant, long-necked herbivores, as well as giant tyrannosaurus-like predators.

They may have evolved slightly larger brains, but there is little evidence that they evolved into geniuses. Mammals are also unlikely to replace them. Dinosaurs had a monopoly on their environment until the time of the asteroid impact.

At the same time, mammals have different restrictions. They never evolved supergiant herbivores and carnivores. But they repeatedly evolved brains. Huge brains (as big or larger as ours) evolved in orcas, sperm whales, baleen whales, elephants, leopard seals, and apes.

Today, some dinosaur descendants — birds like crows and parrots — have sophisticated brains. They can use tools, speak and count. But mammals like apes, elephants and dolphins have evolved the largest brains and the most complex behaviors.

So, does destroying dinosaurs guarantee that mammals evolve intelligence?

Well, maybe not.

Starting points may limit endpoints, but they also do not guarantee endpoints. Steve Jobs, Bill Gates and Mark Zuckerberg all dropped out of college. But if dropping out automatically makes you a billionaire, then every college dropout will be rich. Even if you start in the right place, you need chance and luck.

The evolutionary history of primates shows that our evolution was by no means inevitable. In Africa, primates did evolve into cerebral apes and gave birth to modern humans over a period of more than 7 million years. But elsewhere, primate evolution took a very different path.

When monkeys arrived in South America 35 million years ago, they had just evolved into more monkey species. Primates reached North America at least three times, 55 million years ago, 50 million years ago, and 20 million years ago.

However, they did not evolve into the species that made nuclear weapons and smartphones. On the contrary, they went extinct for reasons we did not understand.

In Africa, and only in Africa, the evolution of primates has taken a unique direction. Africa's flora, fauna, or geography contributed to the evolution of great apes: terrestrial, massive, large-brained, tool-using primates.

Even if dinosaurs disappeared, our evolution needed the right combination of chance and luck.

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