Sparrow-Sized Raptors Left the Smallest Dinosaur Footprints Ever Found

Wednesday, November 21, 2018

A recreation of Dromaeosauriformipes rarus, the tiny new raptor species that's thought to be responsible for the world's smallest dinosaur footprints(Credit: Dr Anthony Romilio)

Most of the records that dinosaurs break are in the "world's largest" category – the biggest foot, the largest land animal to ever walk the Earth, that kind of thing. But now palaeontologists have discovered the smallest dinosaur tracks ever found, which were made by a previously-unknown species of raptor the size of a sparrow.

Discovered in the Jinju Formation in South Korea, each of the footprints measures about 1 cm (0.4 in) long. Although they resemble modern bird tracks, they only have two toes, indicating they were made by raptors. That's because raptors, as you might remember from Jurassic Park, hold their clawed third toe off the ground in a curved position.

The tiny new dinosaur tracks were found in the Jinju Formation in South Korea(Credit: Prof Kyung Soo Kim)

"These 110-million-year-old footprints and trackways were made by carnivorous dinosaurs commonly known as raptors," says Anthony Romilio, an author of the study. "The diminutive sizes of these new tracks are extraordinary; the tracks were made by tiny dinosaurs about the size of sparrows. They are the world's smallest dinosaur tracks."

To find the size of the animal responsible, the team estimated their hip height by multiplying the footprint length by 4.5. This sparrow-size didn't line up with any known species, so the track-maker has been given the new name Dromaeosauriformipes rarus. But there's an obvious question to ask – were these tiny adult animals or just baby dinosaurs of a larger species?

The dinosaur tracks each measure just 1 cm (0.4 in) long(Credit: Prof Kyung Soo Kim)

"Very small dinosaur species like the Chinese Microraptor were crow-sized, but these had feet too large to match the South Korean footprints," says Romilio. "If the tracks were made by dinosaur chicks, we are unclear as to the specific dinosaur that made them, since dinosaurs such as Velociraptor and Utahraptor had larger feet than the ones discovered in these new tracks."

Dinosaur footprints can provide new insights into how ancient animals lived that fossilized bodily remains simply can't. New species emerge, migration patterns come to life, we can see which species lived side-by-side, and even how dinosaurs and early mammals co-existed.

The new study was published in the journal Scientific Reports, and the team brings the new species to life in the animation below.

Source: University of Queensland