In the Late Triassic Period, around 230 million聽 years ago, in what’s now Poland, an early   dinosaur ancestor scampering across the landscape聽 suddenly stopped in its tracks and, wait for it... ...heaved up its lunch.

A glob of plant fragments, fish scales聽 and beetle exoskeletons hit the ground聽聽 with a splat…but that's just the start of  that puddle’s journey through deep time.

See, while body fossils take center聽 stage in museum exhibits and pop culture,聽聽 animals leave behind more than just bones… Because after all, each animal only has one聽 skeleton to submit into the fossil record,聽聽 and even that only has a tiny聽 chance of actually fossilizing.

But over a lifetime, they’ll  leave behind thousands of聽聽 individual excretions - like feces and vomit… Which, when they’re fossilized, are  known as coprolites and regurgitalites,聽聽 respectively … or poop and puke.

And, in their own way, these can be just as聽 interesting and informative as body fossils,聽聽 telling researchers an enormous amount聽 about the animal that left them… Not just their diet, but also their聽 body size, their place in the food web,聽聽 and how numerous they were - giving us a richer聽 understanding of their ecological context.

When other, more conventional聽 lines of evidence fail,聽聽 or when the picture they paint聽 is just incomplete, fossilized聽聽 digestive products (that's a polite term for聽 it) can still fill in big gaps in the story.

And the mystery of how dinosaurs went聽 from small ecological side-characters聽聽 to the icons of natural history they聽 became is exactly one of those times.

While their bones from this pivotal chapter聽 are few and far between, the other clues they聽聽 left behind can reveal how this epic saga played聽 out to those with the stomach to decipher them.

Because, it turns out, the story of the rise of聽 the dinosaurs is a tale written in puke and poop.

You're probably not gonna wanna聽 eat while watching this episode...

The Late Triassic Period, around 230聽 million years ago, was a chaotic time.

Life on land had radiated into a staggering聽 amount of diversity following the End-Permian mass聽聽 extinction 22 million years earlier, with multiple聽 groups competing to fill in newly opened niches.

Apex predator rauisuchids stomped聽 across the landscape, croc-like聽聽 phytosaurs terrorized the water’s  edge, and lumbering herbivores like聽聽 aetosaurs and dicynodont mammal-relatives聽 munched their way through the forests.

In the shadows of the giants, the earliest聽 dinosaur relatives were small, opportunistic聽聽 omnivores, representing just one obscure聽 reptile group in a rich and competitive world.

But over the 30 million years that followed,聽 as the Late Triassic transitioned to the聽聽 Early Jurassic, dinosaurs almost totally聽 eclipsed all that competition, establishing聽聽 one of the most impressive evolutionary聽 dynasties that life on land ever saw.

And while we know that this did happen, the聽 conventional fossil record doesn't capture聽聽 this period of dinosaur success in enough聽 detail to tell us how it all went down.

But in 2024, scientists working in the Polish聽 Basin region of Europe published a study that聽聽 painted a fresh picture of this pivotal聽 transition, albeit with not-so-fresh paint… Because key to their new study was a collection of聽 over 500 fossilized digestive products, spanning聽聽 30 million years, during the final chapter of the聽 Triassic, when dinosaurs exploded onto the scene.

This collection included over聽 100 kg of fossil poop alone,聽聽 plus fossil puke and fossilized intestinal聽 contents - enough data to reconstruct聽聽 the complex food webs of both dinosaurs and聽 their competition during that crucial window.

Now, fossil poop and puke have聽 been used before to study deep聽聽 time – usually to infer the presence of a  species or provide info about their diet.

But using hundreds of individual samples聽 from a single site, tracing across tens of聽聽 millions of years, during a massive evolutionary聽 transition?

That was completely new and exciting.

For many of the fossils,聽聽 the researchers could identify the聽 species most likely to have made them.

They did this by associating them with聽 nearby bones and tracks, and by analyzing聽聽 their size and shape - also known as their聽 “gross morphology”, as the paper puts it.

And, like... ...hit the nail right on the head, yes.

The scientists then performed a聽 series of much more complex and聽聽 sometimes pretty high-tech analyses on the聽 specimens, to reveal their inner secrets… Like chemical treatments to release聽 tiny plant fragments from the samples,聽聽 allowing researchers to tell what kinds of聽 vegetation were being consumed – and how much.

And more than 100 specimens were even sent to a聽 particle accelerator for synchrotron scanning,聽聽 where they were blasted with high energy X-rays.

This allowed the scientists to peer聽 beneath the surface of the fossils聽聽 and build high-resolution 3D models of聽 them, without having to break them open.

Fragments of others were coated聽 with platinum or gold, making聽聽 them conductive enough for a technique聽 called scanning electron microscopy,聽聽 where a focused beam of electrons was used聽 to image their surface in exquisite detail.

So in plain English, what I'm describing聽 is literally gold-plated poop.

After squeezing all the data they could out of the聽 specimens, if you will, and combining it with body聽聽 fossils, trackways, and environmental data, the聽 researchers began to see a story come together… One that unfolded in five phases, with an聽聽 unmistakable ecological turning聽 point around halfway through... At first, in the Late Triassic,聽 around 230 million years ago,聽聽 the ancestors of the first true dinosaurs,聽 like the one we mentioned earlier,聽聽 played just a small background聽 role in the overall environment.

Their coprolites and regurgitalites聽 contain fragments of insects - beetles,聽聽 in particular - as well as fish and plants, too.

But in stage 2, by around 220 million years ago,聽聽 the first carnivorous dinosaurs emerged聽 a little higher up on the food chain.

Fragments of bones appear in their poop and puke,聽聽 showing that they had聽 slightly expanded their niche.

These included the oldest true theropod聽 dinosaurs - the group that would eventually聽聽 give rise to big predators like the聽 tyrannosaurs, carnosaurs, and spinosaurs.

At this stage though, these early聽 carnivores were still small,聽聽 slender, and far from the top of the food chain.

Then, the theropod dinosaurs began diversifying聽 into more – and often larger – predatory species.

And by stage 3, about 210 million years ago,聽聽 dinosaurs as a whole no longer聽 occupied just the ecological margins.

But the highest levels of the food聽 chain were still ruled by non-dinosaurs,聽聽 like this huge predator with the most metal name聽 ever, Smok, whose coprolites and regurgitalites聽聽 are riddled with the crunched and聽 bite-marked bones of its large prey.

And alongside the increasingly diverse聽 predatory theropods in stage 3,聽聽 plant-filled coprolites from the first聽 herbivorous dinosaurs appear, too.

These were likely early ornithischians, a group聽 from which many famous dinosaurs would eventually聽聽 evolve, such as ceratopsians, stegosaurs,聽 and my boy ankylosaurs, just to name a few.

They started small though, and they聽 were still outclassed by the other聽聽 non-dino herbivores like the dicynodont聽 mammal-relatives, who by this time had聽聽 evolved elephant-sized species, such as Lisowicia.

The fossilized digestive contents of聽 the giant Lisowicia suggest that it聽聽 had a more restricted diet, munching聽 mostly on conifer trees - and this聽聽 became important as the trail of poop聽 and puke continued into stage four… Because during this stage, as the Triassic came聽 to a close around 200 million years ago, the聽聽 Polish Basin, along with the rest of the world,聽 experienced a period of environmental chaos.

And for dinosaurs this chaotic opportunity聽 couldn't have come at a better time.

They had聽聽 now gained a foothold in their environment,聽 but weren’t yet super specialized.

Massive volcanic eruptions from the聽 Central Atlantic Magmatic Province,聽聽 combined with tectonic activity on聽 Pangea shifting continents around,聽聽 drove climatic changes that took聽 environments from dry to wet.

And the increased humidity, in turn, led聽 to a turnover in plant life, which many聽聽 of the more specialized herbivores, like the聽 conifer-loving Lisowicia, couldn't adapt to.

The coprolites and regurgitalites left by the聽 early dinosaur herbivores, on the other hand,聽聽 often contain pretty diverse聽 plant species, like ferns,聽聽 cycads, and ginkgo-relatives - including聽 material that had been burned by wildfires.

And this ability to eat a variety of聽 vegetation may have helped those dinosaurs聽聽 adapt to the changing plant life, as other, more聽 conifer-reliant non-dino herbivores died out.

So body fossils, trackways, and fossilized聽 digestive contents all show that herbivorous聽聽 dinosaurs completely replaced non-dinosaur聽 herbivores in the basin at this time,聽聽 while the theropods continued to diversify.

Plant-eating sauropodomorphs would聽 eventually give rise to the largest聽聽 land animals of all time, a journey that聽 began here in stage four with the first聽聽 big dinosaur herbivores emerging from the group.

Finally, in stage five, the earliest聽 days of the Jurassic, dinosaurs cemented聽聽 their advantage and established their聽 uncontested rule over life on land.

The new abundance of large dinosaur聽 herbivores led to a radiation of聽聽 ever-larger dinosaur carnivores that fed on them.

And a new wave of big theropods left behind big聽 fossil coprolites and regurgitalites complete聽聽 with the bones of sauropodomorph dinosaurs聽 and early crocodylomorph prey inside.

Jurassic food webs on land began filling聽 up with diverse dinosaur species at nearly聽聽 every higher level, as they radiated聽 to take advantage of the opportunity.

A mixture of luck and adaptability through a聽 crisis had catapulted dinosaurs to center stage,聽聽 leaving their competition in the dust.

Their reign over planet earth had begun, and聽 it would last for a very, very long time.

Now, fossilized puke and poop still rarely聽 get the appreciation that they deserve… But studies like this are beginning聽聽 to show just how informative these聽 often-overlooked specimens can be.

Pinpointing, at least in the Polish Basin,聽 evidence that environmental changes, biological聽聽 advantages, and a healthy dose of chance聽 paved the way for the rise of the dinosaurs.

And if this approach can be applied elsewhere,聽聽 then it may be the case that, even though聽 we don’t have the body fossils we’d like,   we’ve been sitting on a whole  crap-load of data this entire time.