The Vast and Mysterious Past#

The past is a truly huge and mysterious place. It kicks off at the Big Bang and stretches all the way to the present moment, getting bigger every second. It’s where everything that came before us resides, and it holds the key to figuring out our present. This is where you find the most incredible creatures that ever walked our planet. We’re talking hundreds of millions of species, so varied you can barely imagine them all.

But here’s the thing: the past keeps its secrets pretty close. While we actually know a good bit about what happened, there’s a whole lot more we know we don’t know. And even worse, there’s probably a massive amount we don’t even realize we don’t know about yet.

Think about life right now: We can identify about 1.5 million eukaryotic species, but the actual number alive today might be as high as 10 million. Even though we’re adding around 15,000 new species to our knowledge each year, the vast majority of life currently on Earth is still a mystery to us, undiscovered.

Now, rewind millions of years. It’s estimated that around four billion species popped up on our planet over the eons. But here’s the sad part: at least 99% of them died out way, way before humans even said their first words. Most of these incredible, diverse species are so completely gone that they’ve become part of that deep “unknown unknown” territory of the past, lost to us forever. Or… are they? Could we maybe use science and a bit of imagination to catch just a glimpse, a shadow, of that unreachable past?

How We Learn: The Fossil Record#

Let’s start with what we do know. To get a handle on the creatures of the past, we need fossils. Fossils are basically any preserved leftovers from ancient geological times. This could be bones or shells, or maybe just an impression or an imprint left behind. Sometimes, things even got preserved in amber.

All the fossils ever found on Earth together make up what’s called the fossil record. This is honestly the most important window we have into the past.

For a dead animal to actually turn into a fossil, a bunch of things have to line up perfectly:

• The right environment.
• The right timing.
• The right conditions.

And then, after all that, the fossil needs to survive for millions, even hundreds of millions of years! It has to somehow make its way back towards the surface and then be discovered before natural stuff like erosion just makes it disappear. So, honestly, the fact that we have any fossils at all, and know what we know, is kind of a miracle.

Dinosaurs: A Case Study#

Let’s talk about dinosaurs. They were one of the biggest and most successful groups of animals for something like 165 million years. Plus, they’re just fun to think about and animate! What were they really like, and what are we missing about them?

Over the last 200 years, we’ve dug up tens of thousands of fossils from more than 1000 different dinosaur species. Lately, things have been really exciting – we’ve entered what you could call a golden era of discovery. About 50 new dinosaur species are found every single year! This keeps adding to what we know, and it also helps us realize more of what we know we don’t know about them, which is pretty amazing. But it also makes you acutely aware of all the incredible things completely lost to the past forever.

The “Dinosaur Giraffes” and Lost Worlds#

Imagine taking all the animals that lived in just the last 50 million years. Now, randomly pick just 10,000 individuals from maybe 1000 different species to be the ones that fossilize. Think about everything that would be missed! Or things that might seem too weird to even be true if you only found a tiny bit of a fossil.

Like the Giraffe today. It’s a yellow animal with brown spots, looks a bit like a mix of a horse and an antelope, has a super long neck and two tiny, hairy horns. How many “dinosaur giraffes” were there? Animals so strange, so perfectly adapted to really specific places (ecological niches), that evolution shaped their bodies in ways that might seem totally absurd to us today – maybe they’d look made up!

We know tons of species are just gone forever simply because of where they lived. For instance, think about dense, lush jungles. These places basically prevent fossilization. The chances of an animal getting buried quickly enough there are minimal. There are countless scavengers, big and small, that break down dead animals incredibly fast. Plus, the soil in many jungles is really acidic and can dissolve bones. So, finding dinosaur fossils from jungles is practically impossible.

Today, half of all the known species live in the few rainforests left, which only cover about 2% of Earth’s landmass. Millions of years ago, when dinosaurs were around, jungles covered much, much more of the planet. This means, besides some insects and other small critters sometimes found trapped in amber, there must have been millions of species that appeared and then vanished without leaving a single trace. They’re trapped deep inside that “unknown unknown.”

The Soft, Gooey Problem#

Beyond just the environment, biology itself often trips us up. Look at your own body. It’s mostly squishy, gooey, soft stuff. And that kind of material just doesn’t preserve well over millions of years. What lasts the longest are the hard, crystalized bits of your bones. That’s why most dinosaur fossils we find are bones or teeth – and usually, they’re just fragments, not whole skeletons.

This means that almost all animals without bones or shells are basically erased from the fossil record. If you think about all the amazing diversity of weird, boneless creatures alive today like worms, jellyfish, and slugs, we can only guess at what we’re missing from the past.

Thankfully, many species that are mostly soft and gooey also had incredible, diverse shells. These shells do preserve well and tell us a huge amount about our past, so at least we have those! Still, even our best imagination falls short when we try to picture all the boneless species that might have existed over the last half billion years.

Reimagining Ancient Life#

But hey, it’s not like trying to figure out what something looked like just from its bones is easy either! The way we picture what dinosaurs actually looked like has changed a lot recently. In the past, many drawings made them look very bony and minimal, often with a big toothy grin to show they were fierce and dangerous.

But if you drew animals from today that way, just based on their skeletons, purely for fun, you’d get the most bizarre creatures! Elephants, swans, and baboons would look like monsters straight out of your worst nightmares.

So, just like animals today, we should really imagine dinosaurs with a lot more soft tissue – maybe fat bellies or chests, weird soft bits like skin flaps, lips, and gums, and just generally more pronounced features. This would probably make them seem like much more pleasant fellows than the scary skeletons we used to picture. Some of these soft features can actually leave distinctive marks on bones, which we can look for in extinct animals’ skeletons. This is where looking at modern animals with similar features is super helpful!

Color and Patterns#

It’s a similar story with color. We know what the feathers of living birds look like. Modern technology, combined with incredibly rare fossils that have preserved fuzzy feathers, gives us a peek at the real colors of some extinct dinosaurs.

For example, we know the tiny Sinosauropteryx had a striped tail. Its little dinosaur buddy, Anchiornis huxleyi, was white and black with beautiful red feathers around its head.

Still, for the vast majority of any ancient extinct species, we have absolutely no real idea what color they were. But again, we can look at modern dinosaurs – birds! – and they show an absolutely incredible variety of colors and patterns. So, it stands to reason that some dinosaurs tried to blend into their surroundings. Others might have used bright, aggressive colors to attract mates or to look dangerous. Some might have had impressive decorations or colorful beaks. Maybe some were striped or patterned like a zebra!

Behavior and Personality#

We also don’t know that much about dinosaur behavior. But once more, we can draw conclusions from animals that are alive today. For example, even top predators like lions spend a huge amount of their time just lying around, cuddling, licking each other, and playing. Why would dinosaurs be so different?

When we first found the skull of a T. rex, with its massive teeth and probably the strongest bite of any land animal ever, we pictured it as just a fierce, dumb beast. But modern scanning technology has shown that T. rex actually had a bigger brain-to-body ratio than some earlier giant meat-eaters. It probably had really sharp hearing, vision, and sense of smell. In all likelihood, it was not a stupid animal at all.

So, maybe T. rex was actually a cuddly fellow that spent lots of time playing or trying to impress potential mates when it wasn’t busy being hungry. Similarly, while their horns and bony shields might make ceratopsids (like Triceratops) look like they were just built for fighting, they were probably much more complex than that. Based on how modern animals behave, and the elaborate dances some do just to find a mate, maybe their shields were astonishingly colorful! Maybe they danced for their mates, just like many birds do today.

What We’ve Lost and What We Can Do#

Just thinking about how intensely amazing these creatures must have been is incredible. And what a loss it is for us that we don’t get to see them ourselves, first-hand. What’s an even bigger loss is realizing how much we will simply never know about them. And even more tragic are all those weird and beautiful beings that just vanished without leaving any trace at all.

But that’s just how life goes, isn’t it? Time keeps marching on without caring one bit about our feelings. And the past keeps getting bigger with every moment that passes.

Most wild animals alive today will likely not leave fossils behind either. They’ll also just disappear forever one day. But we can actually do something about that! Instead of speeding up the extinction we’re seeing right now, we could choose to become the guardians of life. We can work to preserve it wherever we find it. If possible, that means protecting it in the wild. If not, then we can preserve its memory and knowledge in museums, in movies, and importantly, right here in our minds. Because as amazing as our imagination is, and as fascinating as it is to ponder the animals stuck in that deep “unknown unknown,” it’s even, even better to be able to witness them here, now, in the present.