World’s Smallest Dinosaur Footprints Found Measuring Just 1 Centimeter

The sparrow-sized Dromaeosauriformipes rarus looks cute, but it was still a tiny carnivore. Dr Anthony Romilio (The University of Queensland)

The world’s smallest dinosaur footprints have been found in South Korea, measuring a tiny 1 centimeter (0.4 inches) long, making this unknown species of raptor the size of a “sparrow” that could fit in the palm of your hand, according to researchers.

Before you go awwww, do you not remember the compys in the opening scene of The Lost World: Jurassic Park? Though they be but little, they are fierce.  

The tiny footprints date back to around 110 million years ago, when dinosaurs shared the Earth with both mammals and birds. The tracks were found in a dried lakebed in Jinju City, which has yielded an abundance of other Cretaceous period creatures from birds and pterosaurs to crocodilians and mammals. These tracks, however, were something else.

Immediately identified as some kind of raptor – bird-like carnivorous theropods made famous by the usually wildly misrepresented velociraptor – what was extraordinary was the size of these tiny relics.

The tiny tracks were spotted by Professor Kyung Soo Kim, nick-named "Eagle-Eye" according to Dr Romilio, for his talent for spotting extraordinary finds. Can you see them? © Professor Kyung Soo Kim (Chinju National University of Education)

“These new tracks are just one centimeter in length, which means the dinosaur that made them was an animal you could have easily held in your hand,” said Dr Anthony Romilio of the University of Queensland in a statement.

“They are the world’s smallest dinosaur tracks.”

The footprint shape was easily identifiable thanks to raptors’ distinctive three-clawed feet. Only two of the toes are actually placed on the ground, the third is retracted, like a cat's.

The researchers, however, are unsure of the species of raptor that could have made these tiny indents, or even if they were adults or babies.

"We do have tiny raptors known from fossil bones from China. Fossil bones of diminutive adult raptors called Microraptor were about the size of crows, with feet about 2.5 centimeters long," Dr Romilio told IFLscience.

"Unfortunately, even though Microraptor was very small (by dinosaur standards) it was still too large for our 1-centimeter tiny South Korean tracks. So perhaps this favours the tracks being made by baby raptors."

If a particular foot shape is only found as tiny tracks in numerous places, it would be easy to conclude that these were made by tiny adults, Dr Romilio explained. However, the same foot shape has been found in larger tracks (some 10 times these ones), which, if they turned out to belong to the same type of animal would make these more likely to be juveniles of a larger (albeit still small) raptor species.

You can see the tiny 1-centimeter footprints in more detail here. Prof Kyung Soo Kim (Chinju National University of Education)

Instead, they are being assigned to a new dromaeosaurid ichnogenus. Dromaeosaurids are a family of small- to medium-sized feathered therapods. Ichnogenera, which means “footprint group”, are any genus that is only known through trace fossils, such as fossilized footprints, rather than remains.

For now, the tracks are being dubbed Dromaeosauriformipes rarus, which means “rare footprints made by a member of the raptor family known as dromaeosaurs,” according to co-author and original discoverer of the tracks, Professor Kyung Soo Kim of the Chinju National University of Education in South Korea.

The tiny footprints are described in the journal Scientific Reports. As for what Dromaeosauriformipes may have looked like, Dr Romilio told IFLScience that though by no means "iron-clad", his reconstruction is based on the fact we know raptors were highly active and closely related to birds. "I have covered them in downy feathers, with bold horizontal striping to be highly visible to each other, and maybe to be easily recognizable by a possible parent raptor," he explained.

OK, you can awww now.

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