Fossilized feces tells the story of the rise of dinosaurs

The contents of feces and vomit from 200 million years ago are helping to show how dinosaurs conquered the world at the beginning of the Jurassic period.

Whole insects embedded in various shapes and sizes of well-preserved plants, bones, fish parts, and even ancient animal feces show that dinosaurs varied in comparison to other groups of animals. This suggests that dinosaurs were able to survive in the ecosystem thanks to their wide-ranging diet. This allowed them to grow and eventually establish a “land dynasty,” says Martin Kvarnström of Sweden’s Uppsala University.

Fossil evidence shows that the first dinosaurs, with hip joints that put their legs under their bodies like mammals rather than sprawled sideways like lizards, appeared more than 230 million years ago. It has been shown that For tens of millions of years, these early dinosaurs blended into a landscape filled with many other types of reptiles. But by about 200 million years ago, dinosaurs had essentially taken over the Earth, and most other reptiles disappeared in the end-Triassic extinction.

What led to dinosaur dominance remains somewhat of a mystery. Kvarnström and his colleagues suspected that important clues might be hidden in the bromalites (fossilized feces and vomit) of dinosaurs and other animals. There, they assembled 532 bromalites stored at the Polish Geological Institute that a previous research group had collected from eight Polish sites between 1996 and 2017.

The researchers estimated the age of each bromalite based on the layer of sediment in which it was found, and matched it to its size (from a few millimeters to a “fairly large fecal mass”) and the animal that likely produced it. I used a shape that They then 3D scanned the fossil to examine its contents. “We noticed that it was clogged with food debris,” Kvarnström says.

Combining the known fossil record with past climate information, researchers determined that the emergence of dinosaurs occurred in several different stages. First, the omnivorous ancestors of early dinosaurs began to outnumber non-dinosaurs. They then evolved into the first carnivorous and plant-eating dinosaurs.

At that point, increased volcanic eruptions and movement of tectonic plates caused flooding and waterway development. The resulting humidity and related changes in climate likely led to a wider range of plants and the evolution of larger and more diverse herbivorous dinosaurs. On the other hand, animals other than dinosaurs (such as 1-ton dicynodonts) Lisowisia, Their feces contained mainly coniferous debris and they were unable to adapt to changing plant types.

As herbivorous dinosaurs grew larger, so did their predators. By the beginning of the Jurassic period, about 30 million years after the first dinosaurs appeared, the transition to a dinosaur-dominated world was complete, Kvarnström says.

“This study shows how climate primarily affected dominant plants, which created opportunities for new herbivores at certain points in time,” said a researcher who was not involved in the study. says Michael Benton of the University of Bristol, UK.

Although it’s difficult to be sure whether the researchers matched the feces with the right producers, the discovery nonetheless suggests that the dinosaur species had already expanded significantly before major climate change in South America. This supports earlier research, he says. “But it took the end-Triassic mass extinction for the final stage of the takeover to begin.”

For Emma Dunn of Germany’s Friedrich-Alexander University, this research helps answer long-standing questions about the emergence of dinosaurs. “It’s not every day that a fossil poop is published in such an influential journal,” said Dunn, who was not involved in the study. “This is obviously interesting, but it’s also very useful for understanding prehistoric environments. So if you think of the evolution of early dinosaurs like a jigsaw puzzle with pieces missing, there are new It’s just a lot of pieces thrown in.”