Scientists Make a Breakthrough Discovery – in Dinosaur Poo

One day in the Triassic, a Silesaurus was wolfing down a meal. 230 million years later, hi-tech scanners reveal what she ate

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A reconstructed proto-dino Silesaurus, in Poland's Museum of Evolution.
A reconstructed proto-dino Silesaurus, in Poland's Museum of Evolution.Credit: Hiuppo
Ruth Schuster
Ruth Schuster

One day in the Triassic, a Silesaurus ate a meal. The repast consisted in whole or largely of insects.

Some 230 million years later, scientists at Sweden's Uppsala University studied the early dinosaur's droppings using cutting-edge synchroton scanning technology. They realized they had come across, among other insects encased for eternity in the poo, an unknown species of beetle.

Appropriately enough, they named the beetle Triamyxa coprolithica, the authors say in their paper published in Current Biology.  A coprolite is a fossilized piece of poop.

This marks the first time that any new species, albeit in this case an extinct one, has been discovered in fossil droppings. Frankly, the photo of the beetle, from a scanner, looks like it was found in a pile of poo. Where's Photoshop when you need it?

Triamyxa coprolithica: Not a tick.Credit: Qvarnstrm et al.

Despite any objectionable outer coating, some of the samples were in fantastic shape considering their age and provenance. "I never thought that we would be able to find out what the Triassic precursor of the dinosaurs ate for dinner," stated co-author Grzegorz Niedewiedzki, a paleontologist at Uppsala.

How do we know that's who ate the bug? We don't, in fact. But it is a plausible hypothesis. Its remains were found in the same area.

Silesaurus weighed about the same as three cats, or a beagle. It looked sort of like a greyhound with a small beak at the end of its mouthpart and a dinosaurian tail. It was about 7.5 feet long from nose to tail-tip, according to reconstructions based on the roughly 20 specimens found to date. Silesaurus wasn't a dinosaur per se, but a predecessor of the great (and less great) beasts, known as a dinosauriform. This proto-dinosaur was described at length in the Journal of Vertebrate Paleontology in 2003. 

Silesaurus, a Triassic precursor of the dinosaur and a cutie.Credit: Magorzata Czaja

The animal could have used its beak the same way its descendant, the bird, would: to pick up insects off the ground, among other things, which it then chewed with its irregular teeth. It dwelled in what is today Poland (and presumably much farther afield, too) and Silesaurus remains have been associated with coprolites replete with beetle corpses in previous research.

In an earlier study, the authors assigned coprolites with fragmentary beetle remains to Silesaurus based on the size and shape of the coprolites as well as several anatomical adaptations in the animal.

Triamyxa coprolithica was no giant either, and the authors say that Silesaurus, or some other ancestral dinosaur, ate it in large numbers. Most of the beetle body parts in the coprolites were of this same small species and, wondrously, a few specimens were found nearly complete, with much of their delicate little legs and even their antennae still intact.

Because it was so miraculously preserved by being entombed in feces and then fossilized, the entomologists could compare it with modern beetles. Their conclusion: it came from a previously unknown extinct lineage of the suborder Myxophaga.

The Myxophagans clearly go back a long way, as we knew from species in amber and now from this Triassic dump.

The tiny beetle Triamyxa coprolithica is the first-ever insect to be described from fossil feces.Credit: Qvarnstrm et al.

Myxophaga are the second-smallest beetle known to humankind. If you take your glasses off, some of them look a lot like ticks. Some still resemble ticks with your glasses back on, but they don't suck on blood and transmit diseases – they eat algae cells and live in wet environments. That, too, fits the picture of Silesaurus' lifestyle: Triassic Poland was, apparently, a swamp.

"We were absolutely amazed by the abundance and fantastic preservation of the beetles in the coprolite fragment. In a way, we must really thank Silesaurus, which likely was the animal that helped us accumulate them," states Martin Qvarnström, researcher at Uppsala University and one of the co-authors of the paper.

So Silesaurus, we thank thee for eating beetles – probably not confining itself to the Triamyxa because they were so small and unsatisfying, sort of like popcorn in lieu of a chicken leg.

"Although Silesaurus ingested numerous individuals of Triamyxa coprolithica, the beetle was likely too small to have been the only targeted prey. Instead, Triamyxa likely shared a habitat with larger beetles, which are represented by disarticulated remains in the coprolites, and other prey, which never ended up in the coprolites in a recognizable shape," the authors explain.

It could be that the Silesaurus chewed up the bigger beetles, but the small ones just got swallowed whole, like we eat sesame seeds; and the rest is history.

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