Scientists have charted how dinosaurs rose to prominence using a pretty unconventional method. They studied, in dirty detail, hundreds of samples of fossilized poop and vomit.
Huge piles of dino droppings would have been a common site in the Mesozoic era, and like other biological matter from deep history, a small fraction of those feces fossilized into what are called coprolites. This waste doesn’t have to go to waste though – scientists can analyze it to get a better picture of dinosaur diets.
In a new study, scientists in Poland, Sweden, Norway and Hungary set out to conduct the most comprehensive study so far of fossilized remains of digestive material. Yes, that’s fossilized poop and vomit, also known by the technical term of bromalites.
This wasn’t just an early entry into next year’s Ig Nobel Prizes though – by studying 500 separate bromalites of different ages, the researchers could build snapshots of food webs, and how they changed over time. They added other data to the mix, including footprints and bones, some of which had bite marks, to get a more detailed picture.
Some bromalites were cracked open and studied slice by slice, while others were scanned in 3D to see what was inside them. The researchers saw fragments of insects, as well as some small specimens still intact. Scales, teeth, pieces of fish and the crushed bones of larger prey were found in some samples, and of course plant matter was common to others, with some specific species still identifiable.
The contents of the bromalites, as well as their size, composition and abundance, was cross-checked with fossil records like bones and footprints of the same ages. This allowed the team to infer the identity, eating habits, relative size and prevalence of the creatures that left them.
When the scientists arranged these insights into a timeline, a picture began to emerge about how dinosaurs rose to dominate the planet. Their decline is well studied – we know their reign ended 65 million years ago after a gigantic asteroid impact. But less is understood about their origin story.
Fossil evidence suggests that the first dinosaurs appeared about 230 million years ago, in the mid-to-late Triassic period. Their development was fairly slow, but by the dawn of the Jurassic, about 30 million years later, they were thriving, with diverse forms having taken over almost every ecological niche.
The new study fills in the gaps about how they managed such a successful run. The ancestors of early dinosaurs were small and omnivorous, and were far outnumbered by other vertebrates. But as climate shifts increased the diversity of plants and flowers, herbivorous dinosaurs grew larger and more prevalent. In response, carnivorous dinosaurs appeared, diversified and flourished as well.
Their ability to adapt led the dinosaurs to outcompete non-dinosaurian land vertebrates, so that by the end of the Triassic the dominance of dinosaurs was complete.
It’s an intriguing story, told through a creative medium, but it’s important to note that it’s not the full picture. The samples were all taken from one region of Poland, so they might not necessarily be applicable to the whole world. But the team says that the same method could be performed on samples from other places to see if they follow a similar pattern.
The research was published in the journal Nature.
Source: Uppsala University
