Palaeontologists have found a 230-million-year-old beetle species, with legs and antennae intact, preserved within fossilised dinosaur poo.
The discovery, published in the journal Current Biology, opens up the possibility that fossilised dinosaur droppings – known as coprolites – could be a rich new source of information about ancient insects otherwise inaccessible to science.
The most common source of information about ancient insects is amber, the hardened tree sap that can preserve insects and other tiny creatures almost perfectly.
But while insect fossils from amber date as far back as about 140 million years, this new research suggests coprolites may offer researchers an even deeper view of the past.
“We didn’t know how insects looked in the Triassic period and now we have the chance,” says Martin Fikáček, an entomologist at National Sun Yat-sen University, Taiwan, and a co-author on the paper.
“Maybe, when many more coprolites are analysed, we will find that some groups of reptiles produced coprolites that are not really useful, while others have coprolites full of nicely preserved insects that we can study.
“We simply need to start looking inside coprolites to get at least some idea.”
The coprolite was scanned using synchrotron microtomography at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France.
The method operates similarly to a CT scanner, but with strong X-ray beams that can image the internal structures inside fossils in high resolution.
“I was really amazed to see how well preserved the beetles were, when you modelled them up on the screen,” says lead author Martin Qvarnström, a palaeontologist at Uppsala University, Sweden.
“It was like they were looking right at you.”
The team named the new beetle species Triamyxa coprolithica, referring to its presence in the Triassic era and its discovery in coprolites.
The beetle probably lived in semiaquatic or humid environments, and was most likely consumed by Silesaurus opolensis, a beaked dinosaur ancestor about two metres in length that lived in what is now Poland.
“This is an extraordinary breakthrough for palaeontology,” says John Long, a palaeontologist at Flinders University, Adelaide, who was not involved with the study.
“I saw a young Martin Qvarnstrom as a student present his work on coprolites at a palaeontology meeting in Canada a few years ago, and my jaw dropped at what I saw.
“Unlike amber, poo has been around since the first animals ate things.
Following that reasoning, Qvarnström says this new line of research may help scientists to understand more about the ecology and food chains in ancient ecosystems.
“There are heaps of things you can study based on fossilised droppings, but it had been hard to understand what to do with it, hard to recognise what is inside, and hard to draw conclusions from it, but now there are tons of data,” he says.
“The ultimate goal is to use the coprolite data to reconstruct ancient food webs and see how they changed across time.”