Fossils aren't just cool to look at.

I mean, they totally are. But they're full of important information, too.

They tell us about animals that have been gone for hundreds of millions of years, revealing what they might have looked like, where they lived, and sometimes how they lived. And the reverse also happens. Examining fossils that are millions of years old could help us learn more about the species that still exist today.

So let's explore our favorite fossils from 2025 and all of the amazing things we learned from them. [ INTRO MUSIC ] Our first fossil was discovered on the Isle of Wight in southern England, which is home to some amazing fossil deposits. It's an Iguanodontian, and it not only represents a species that's new to science, but also reveals information about a unique physical feature, but the discovery of the fossil itself isn't new. This particular dinosaur skeleton was found in the 1970s and donated to a museum collection.

And because there were two known species of Iguanodontian and from the site already, people just assumed it was one of those two, and basically let it gather dust for decades. But this one is actually pretty different enough that a new research group took another look at it this year and decided it deserved. A brand new name is

Istiorachis macarthurae This guy had extremely exaggerated spines emerging from its backbone, which are tallest over the back legs and run all the way down its long tail.

And while this fossils other known cousins have similar backbone extensions, this one was extra tall. These bony extensions would also have been covered in skin and tissue. When this animal was alive, creating basically a huge sail that ran from its head to its tail.

While nobody's exactly sure why exactly dinosaurs would have evolved such spiky spines. Researchers have a few hypotheses. The sales could have played a role in protecting their spinal cord from potential injury, or act as a means of regulating body temperature, or as a way to ensure closely related species know who's who in the case of this Iguanodontian.

The researchers think inter-species signaling might play a role, but that the sales primary purpose was for sexual signaling. A taller sail would make you look bigger and buffer to a potential mate while intimidating rivals. And by comparing this new species with other Iguanodontian dinos the new research on old bones revealed that earlier species had smaller spines and their impressive sails got even taller and more elongated in the late Jurassic period and then in the Cretaceous period.

The many species of sail box dinosaurs had a lot more variety in sail size. While it's a rare feature, sail show up in a handful of species today, too. Some lizards have them, including some chameleons, basilisks, and the appropriately named sail fin lizards.

And in almost all of them, the sails are a lot less developed in females than males, which hints that the sails biggest benefit might be in attracting a mate. But it also tells us that if it's consistently a male centric trait today, it could very likely have been one millions of years ago, too, which means that it may be time for the other hypothesis to set sail. Let's jump from sailing to flying with an adorable and gravity defying group of squirrels.

When it comes to studying the evolution of flying squirrels, it can be hard to fill in all the gaps for one crucial reason. Today, there are some smaller flying squirrels in North America and some larger ones. The appropriately named giant flying squirrels found in Asia.

While you might know a flying squirrel when you see one alive and well, it's a lot harder to identify a flying squirrel fossil. For one, they don't actually have wings. Instead, they have a skin membrane that stretches between their limbs that allow them to glide, and skin is generally not very fossilization friendly.

So knowing which squirrels did or didn't have their built in gliding suit can be challenging. Wrist bones can shed a little light on how sturdy and stable a gliding squirrel's limbs might have been, but they're rare to find because they're so itty bitty. So most of what we know from the evolutionary history of flying squirrels, we know from fossil teeth we found.

We know the flying squirrels likely first showed up in North America around 36 million years ago, and while they did pretty well in other parts of the world, their populations dwindled there. There's even a 4 million year gap right around the end of the Miocene, where there are no known flying squirrels, despite their cousins in Asia pretty much thriving. At the same time, fossils from around the time of the last ice age were found in what is now Florida in the USA, and were thought to be from a genus new to North America.

But it wasn't a solid connection, but a paper published in the Journal of Mammalian Evolution this year not only took another look at these past Florida finds, but also looked at a new fossil assemblage from what's now the state of Tennessee. And while they pretty much only found teeth, they used those teeth to estimate the body size of the squirrel who grew them. Turns out that the warm weather in ancient Tennessee made it the perfect home to squirrels.

The size of house cats. The Tennessee and Florida fossils are pretty close relatives of the long gone Eurasian species, and to today's remaining giant flying squirrels of Asia. And given that the fossils are thousands of kilometers away from other similar giant flying squirrel fossils, it's looking like their ancestor population took advantage of warm periods in the very early Pliocene period, about 5 million years ago.

These Eurasian squirrels would have spread from Asia into North America via the Bering Strait, when everything was warmer, and then got stuck in the south as the top parts of the continent got too cold for them. They stuck around as long as they could, and a few remaining warmer zones to the south. But expanding cool conditions sadly left us without any flying squirrels of the giant variety this side of the pond.

Nevertheless, these giant ancient flying squirrels still got to glide their way onto this list and into our hearts. But before we get to our next favorite fossil, here's a quick ad from this video's sponsor. This SciShow video is supported by brilliant, the online learning platform.

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You'll get 20% off an annual premium subscription. Hey, remember how I just said that soft tissues like skin don't really show up in the fossil record? Well, our next fossil didn't get the memo because it includes skin that's well over a hundred million years old.

Plesiosaurs are iconic ancient reptiles known for being some of the largest marine predators in the fossil record, with big flipper limbs usually paired with a long neck. They were widespread across the globe for more than 140 million years, and while their bone fossils have been found a lot soft tissues not so much, but a newly discovered skeleton was not only nearly complete, but also had traces of skin on both the tail and one of its front flippers, and having skin from two areas helps researchers see how textures varied across the animal's body. This plesiosaur had smooth and scaleless skin on its tail, but along the rear edge of its flippers it was scaly.

Think of a mix between the hard plates on a turtle shell and modern reptile scales. The researchers think these scales might have played a role in hydrodynamics, stiffening the back edge of the fin and giving them more control as they swam through the seas. It also might have helped with gripping surfaces while feeding on the ocean floor, because Plesiosaurs were thought to bottom walk the seafloor searching for food in the sediments.

Or maybe it was both. Either way, this fossil is one case where the beauty really is skin deep. Now, fossilized bones and skin are cool and all, but we don't need to find fossilized body parts to learn a lot about ancient life on Earth.

A newly discovered Scottish fossil site on the Isle of Skye was found to contain the footprints of multiple different types of dinosaurs sauropods, the long necked quadrupedal vegetarians, as well as theropods, the three toed bipedal predators, and the group that includes such celebrity species as Tyrannosaurus rex. We're not just talking about a few footprints, either. They discovered 131 tracks.

These particular tracks were made about 167 million years ago in the Middle Jurassic, and they'd all been left in a rippled sand, which was slightly submerged in the shallow waters of a subtropical lagoon. Back then, where we're all these dinosaurs headed, well, the tracks seem to meander back and forth and don't have much clear direction, so it seems they may have just been enjoying a stroll. Plus, they didn't seem to really be interacting with one another.

That also tells us these dinosaurs probably walked across this same mudflat at different times, which is why they weren't interacting with each other. The discovery might help clarify the identity of previously found fossils, too. At a nearby site, there were some similar impressions that hadn't been identified as footprints at all.

Instead, those researchers had mistaken them for fish burrows. But those so-called burrows have a lot of the same features that the sauropod footprints do. Leading researchers to conclude that they were footprints, too, just not as well preserved.

So this site could pave the way for reevaluating similar finds elsewhere. There were also a lot more carnivorous theropods at this site than have been found at similar lagoons. That might mean there was something unique about this place that made it a good place for these predators to hang out.

Pretty cool that the fossil record just happened to preserve their favorite stomping ground to all those years later, fossils can definitely reveal a lot about a very different time and place, but other times they show us that some things never change. Like bathroom etiquette. The rock hyrax is a small herbivorous mammal found today in Africa and the Arabian Peninsula.

They are short, furry, stocky, tailless, and very cute. Oddly, their closest living relatives are elephants and manatees, so they don't really look like the rest of the family. But that's not the weirdest thing about them.

Rock hyrax does have some questionable housekeeping habits. They use communal toilet areas, building up layers of urine and feces in the same place. Generation after generation.

They also have a tendency to drag their butt across the sand, a habit that cat and dog lovers might be all too familiar with at home, though if your cat or dog is doing that, you might need to bring them to the vet. FYI, we don't really know for sure why hyraxes do it, though I'm sure you can make some guesses. And what was a lot of evidence from their close relations and the fossil record Traces of hyraxes themselves have been missing from it.

Even today, with a lot of rock hyraxes around, we rarely find evidence of their tracks, which does make intuitive sense because they like to hang out on rocks. That said, they do travel across sandy dunes to reach their favorite plants for munching, and that seems to be what happened at a fossil site in what is now South Africa. Researchers have discovered what appear to be ancestral hyrax tracks in sandy substrate from the Pleistocene and better yet, at another site nearby.

They also found what could very well be a 126,000 year old hyrax. Butt drag. This fossil track bears a striking resemblance to the markings left by hyrax booty scoots today, plus a small raised bump at one end of the track might have been a dropped cluster of poop left behind as a result of the drag, if they're right about their hyrax.

Butt drag hypothesis this site would be some of the only evidence of hyrax ever recorded in the fossil record, and this appears to be the first butt scoot of any animal in the fossil record. Globally. They also pointed out that since hyrax public toilets might go back tens of thousands of years, these latrines themselves should be considered as trace fossil sites, trapping pollen and other microscopic remains.

So next time you see your dog scooting his way along the carpet, know that he is just one of many mammals over the ages to enjoy the simple pleasure of scratching your butt. These are just a small handful of the amazing fossil finds that were published in the last year. But as you can see, whether it's a set of massive spines or a small butt drag to free up some poop fossils can reveal all kinds of amazing information about what walked the earth millions of years ago.

Okay, video's over now now scoot. [ outro music ]