New beetles found in ancient dinosaur poo

A family of previously unknown beetles have been uncovered in the unlikeliest of places: in samples of 230 million year old fossilised dinosaur poo! Scientists from Sweden and Taiwan were using high-energy X-ray beams to probe samples of fossil coprolites to produce high-resolution 3D images of what lay within. What they saw took them quite by surprise, as Sally Le Page heard from lead author Martin Qvanström...

Martin - Complete beetles - a few specimens that were almost complete. It was like you modelled them up in 3D at the screen, and they almost looked back at you from the screen. And this was truly amazing because we didn't expect to find such complete specimens. We could use the complete specimens and the small body parts to actually describe this beetle and describe a new taxonomy. It's a new genus species and even a new family of beetles.

Sally - Who did the poo? What is the animal that we're talking about that's eating all of these insects?

Martin - The problem with fossilised poo is that it's very hard to understand who produced it, right? Because you don't have so many clues at hand, but you have to use all the kinds of clues you have - the contents of them, the size, the morphology, so the shape of the coprolites. And also understand the body fossil records, so the bones from the same site. And the best candidate to produce this coprolite is a really close dinosaur relative, so a cousin to the dinosaurs called Silesaurus opolensis. It was a fairly small, medium sized animal - weighed approximately 15 kilos, 2 - 2.5 metres long, including the tail. It was a relatively small animal and it was lightly pecking insects off the ground, or rooting around in the litter with a little interesting beak that it had. So it was probably eating beetles and other insects in degraded wood or in like a moist environment.

Sally - And how old is the poo, how old are these insects?

Martin - So the poo is 230 million years old, so it's from the Triassic period.

Sally - That's an old poo!

Martin - I agree, I agree! And it's from a very interesting time because it's when we get the first dinosaurs. And when we think about the dinosaurs, we think about like these ecologically dominant animals, right? But for the first 30, 40 million years of evolution it was not like that. Actually in the beginning, they were just minor ecological components of the ecosystem. And the first time dinosaurs are already around in different areas of the world, but they haven't taken over, so to speak, yet. So it's a little bit interesting because diets play a role here in trying to understand what happened, why dinosaurs became so successful. We don't know that yet, so this is a little piece to that puzzle.

Sally - So this is before the T-Rex, the triceratops?

Martin - Way, way before. So if we think about T-Rex, for example, it's like 66, 70 million years ago. So the time gap, the time difference between us and T-Rex is much, much smaller than between T-Rex and the Silesaurus opolensis and the age of the fossilised poo here, it's incredible.

Sally - How did the beetles get inside the poo?

Martin - There are two possibilities here - either they entered the poo when it was already laying on the ground, or they were ingested. And why we think they were ingested is that we have so many of them in the coprolites, and there are various stages of disarticulation. So most are just bits and pieces of, you know, chewed up beetles. And then we have the few exceptions, so it's just really two specimens that are near complete.

Sally - Why can't you just look at insect fossils. Why are you looking inside the poo to find the insects?

Martin - If think about like the most beautifully preserved insect fossils, they're from Amber, and Amber is all nice and good. So it's fossilised tree resin.

Sally - Like that mosquito in Jurassic park.

Martin - Exactly, yeah. So you can look at hundreds of specimens and just under the microscope and see where the nice insects are. The problem with Amber is that it was mainly formed during relatively young geological time. So when it comes to early beetle evolution and early insect evolution, we don't have any insect fossils from Amber to rely on. So this really fills that gap. It's like, Hey, okay, we don't have an Amber, but we can look in, in coprolites, so in fossilised poo, and we find almost the same preservation.

Sally - Are you just going to go around scanning all of the coprolites, all of the poos in museums now?

Martin - That's pretty much what my last 5 years have been all about! With scanning maybe 100 specimens. And we're trying to analyse a lot of coprolites from the same locality, and then try to reconstruct food webs

Sally - I have to ask, does fossil poo smell like poo?

Martin - No, fortunately not. I work with them every day, so that would be really hard for me!