When paleontologist Martin Qvarnström began peering inside 230-million-year-old fossilized dinosaur dung using an advanced X-ray technology, he wasn’t sure he’d see anything of interest.
But embedded in ancient excrement, he discovered multitudes.
Scans revealed tiny beetles with antennas and delicate legs intact, crushed bones from extinct crocodile ancestors, half-digested fish and an abundance of plant life within the bromalites — fossilized feces and vomit — of early dinosaurs and the creatures that roamed alongside them.
From paleontological poop, Qvarnström and colleagues reconstructed the ecology, biology and food webs that wove together the early dinosaur ecosystem in the Polish Basin in central Europe from 230 to 200 million years ago. The research, published Wednesday in the journal Nature, focuses on a critical, but obscure, period in the late Triassic and early Jurassic, when the first dinosaurs appeared in that region and rose to dominance — part of a major turnover in life on Earth.
The picture that emerges from the study of more than 500 bromalites — mostly coprolites, or droppings — is one of a gradual process of change. Small dinosaur ancestors opportunistically took advantage of food sources made more abundant by environmental changes, evolved into larger creatures and widened their ecological niche.
Stephen Brusatte, a paleontologist at the University of Edinburgh who was not involved in the study, called the deep dive into dino droppings “insightful and innovative,” for putting some of the “most maligned fossils” under scrutiny.
“Academic paleontologists can be prone to toilet humor, too,” Brusatte wrote in an email. “But wow, (bromalites) can give us a lot of information. This is exactly what we need to understand the predator and prey links from millions of years ago.”
The celebrities of the paleontological world tend to have giant footprints and outsize bodies — the fearsome apex predators and charismatic herbivores whose skeletons fill museum halls and ignite the imagination.
Fossilized digestive contents, on the other hand, tend to be stored in basements and are often the object of jokes, said Grzegorz Niedzwiedzki, a paleontologist at Uppsala University in Sweden and the senior author of the study.
But look close enough and they can reveal details about how dinosaurs lived — what they ate, how they fit into their ecosystems and how that changed over time.
The authors used their study to construct a food web, with arrows showing what and who prehistoric creatures were chowing on. When the first dinosaur ancestors came on the scene in present-day Poland some 230 million years ago, they were small, omnivorous and opportunistic silesaurids. The study reveals they filled their stomachs with tiny beetles, among other food.
Carnivorous dinosaurs appeared around 220 million years ago. Herbivorous dinosaurs emerged about 10 million years later. Around 200 million years ago, the plant-eaters may have gained an advantage when the climate became more humid, favoring dinosaurs with a wider palate, who expanded from a mostly conifer diet to consume ferns and other plants that became more abundant.
This dietary flexibility may have helped allow for the emergence of larger dinosaurs. Then, they began to become far more diverse and spread geographically.
While the question of how the non-avian dinosaurs went extinct is a source of wide fascination, the question of how they came to rule in the first place remains remarkably obscure.
The new study closely followed the record in one part of the world, and a similar approach could now be used in other regions, to discern if the food webs were similar and identify differences in how dinosaurs rose to dominance.
The new study favors the idea that dinosaurs were well-suited to take advantage of changes in the prehistoric environment, but also reveals that the age of the dinosaurs had a slow, complicated start.
“Dinosaurs did not simply sweep across ancient Poland and the rest of the world soon after they originated, like a marauding army,” Brusatte said. “It took them time, and patience, and a lot of adaptation, all while being affected by the evolutionary whims of the other organisms in their food webs.”
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