“Fossilised faeces are like little treasure chests”

“Fossilised faeces are fantastic. They are like little treasure chests full of valuable information about what the animals ate, who ate what, or whom. If you piece it all together, you can see how ecosystems were structured and follow them over time, which is what I’m interested in,” explains Martin Qvarnström in the Forskarpodden podcast.

But it takes practice to learn how to find and recognise dinosaur droppings.

“In some cases, it’s a piece of cake because it literally looks like a piece of poop – something that a dog would have left behind, segmented just the way you would expect a piece of poop to look. But in other cases, it’s a little trickier. If we take these large carnivorous dinosaurs, the faeces can be 30–40 cm in size and an accumulation of bone fragments from prey rather than the standard sausage shape,” he explains.

By examining the digestive remains, it is possible to find out not only what the dinosaurs ate, but also how they ate.

“There have been times when we’ve found chewed-up bone fragments from other dinosaurs. That tells us that they chewed on bones to get at the marrow and bone salts – a bit like hyenas do today, but not something you really associate with dinosaurs,” he says.

Clues in the remains

Clues to behaviours not directly related to eating habits can also be found in the remains.

“In some cases, we find things in the coprolites, i.e. these fossilised faeces, that we don’t otherwise find in the sediment at the sites where we dig. This means that the animals that left the faeces moved over much larger areas than just locally, which tells us something about their habitat,” Qvarnström explains.

Coprolites are often found at palaeontological excavations, but it was not until quite recently that it became possible to analyse them. With the help of modern technology, the contents can now be examined without damaging the find.

Three-dimensional images

Qvarnström and his colleagues use a synchrotron scanner, which can be likened to a more powerful version of the CT (computed tomography) scanner used in healthcare. This allows them to produce three-dimensional images that show precisely everything in the faeces, enabling them to say with certainty that the eating habits of different dinosaurs differed greatly even early in their development.

“There were all kinds of early dinosaurs: some small opportunistic dinosaurs that ate insects, fish and so on, and early herbivorous dinosaurs that were more generalist than other earlier herbivores. It’s not just dinosaurs we’re interested in. We’re looking at all different kinds of animals in these ecosystems,” he says.

Droppings are not the only thing Qvarnström is examining in his quest to understand how dinosaurs became the rulers of the Earth.

“If you want to make it really interesting, you have to look at what we can find in the faeces, bite marks on bones, the different types of skeletal fossils we have, footprints, plant fossils, climate data. We build up a comprehensive picture of these ecosystems. It’s something that takes a lot of time and a great deal of labour. So it’s an ambitious undertaking, but in the long run it can provide extremely interesting new insights into how these ecosystems change over time,” he says.

The history of dinosaurs dates back over 235 million years. The oldest finds have been made in Argentina and Brazil. In the space of 30 million years, they went from being fairly marginal in ecosystems to dominating the world.

A discovery in Skåne

A few years ago, a discovery in Skåne caused a stir that reverberated around the world. Qvarnström and his colleague Grzegorz Niedzwiedzki had travelled there to search for traces of early dinosaurs. They hoped to be lucky enough to find new footprints. And they found what they were looking for – and much more than that.

“First we found a tooth and some bone fragments and realised there must be a lot of cool stuff preserved at this site. And little by little, we made more and more exciting discoveries,” Qvarnström recalls.

What has made the most headlines so far are the footprints and skeletal remains of enormous, 201-million-year-old predatory dinosaurs.

“Some of these carnivorous dinosaurs we’ve found, their footprints among other things, are insanely large. These early dinosaurs aren’t supposed to be that big. What’s more, this is an extinction interval. But in Skåne, we have dinosaurs that are 8–10 metres long. They may not quite be T. rex size, but they’re not far off,” says Qvarnström.

Åsa Malmberg