April 2019, ScientificAmerican.com 13PALEONTOLOGYTiny Dino
A carnivore left the smallest
known dinosaur footprintsA series of one-centimeter-long, 110-million-
year-old footprints found in South Korea were
left by what may be the tiniest nonbird dinosaur
ever discovered. “These were made by several
incredibly small raptor dinosaurs,” says Anthony
Romilio, a co-author of a study detailing the dis-
covery and a postdoctoral researcher in paleon-
tology at the University of Queensland in Aus-
tralia. “Prior to our find, there would have been
few who would have imagined that some rap-
tors were so small that two or three could have
easily fitted in your cupped hand.”
Each footprint resembles the number 11,
suggesting that these creatures walked on
two toes per foot. The only dinosaurs known to
match this style of prints are dromaeosaurs—
a family of speedy predators that included
Velociraptor mongoliensis, of Jurassic Park fame.
These raptors had four toes on each foot; one
was diminutive like a cat’s dewclaw, and anoth-
er had a sickle-shaped claw and was held
above the ground while a raptor walked.
The sparrow-sized dromaeosaurs that left
these footprints would have had hips that were
only four to five centimeters high. Their tracks,
found in the South Korean city of Jinju, were
de scribed last November in Scientific Reports by
a team led by Kyung Soo Kim of the country’s
Chinju National University of Education.
The prints look like they were left by an adult
dinosaur smaller than any known type other
than birds, Romilio says. Still, the possibility
remains that a clutch of dinosaur chicks could
have made them; similar footprints 10 times big-
ger—possibly from an adult—have been found
at a site 30 kilometers away. Skeletal fossil evi-
dence from the region is needed to pin down
which hypothesis is correct, Romilio notes.
“Most people expect dinosaur tracks to be
huge, bathtublike depressions, and some
dinosaurs did leave some pretty big holes in
the ground,” says Anthony Martin, a paleon-
tologist at Emory University who studies trace
fossils (such as footprints and burrows) and
was not involved in the study. But the new
finding “shows us that we also sometimes
need to think small.” Even if the footprints
were left by hatchlings, he adds, they hint that
these juvenile dinosaurs were precocious and
able to leave their nest soon after hatching,
similar to some modern birds. — John PickrellPALEONTOLOGYTiny Dino
A carnivore left the smallest
known dinosaur footprintsA series of one-centimeter-long, 110-million-
year-old footprints found in South Korea were
left by what may be the tiniest nonbird dinosaur
ever discovered. “These were made by several
incredibly small raptor dinosaurs,” says Anthony
Romilio, a co-author of a study detailing the dis-
covery and a postdoctoral researcher in paleon-
tology at the University of Queensland in Aus-
tralia. “Prior to our find, there would have been
few who would have imagined that some rap-
tors were so small that two or three could have
easily fitted in your cupped hand.”
Each footprint resembles the number 11,
suggesting that these creatures walked on
two toes per foot. The only dinosaurs known to
match this style of prints are dromaeosaurs—
a family of speedy predators that included
Velociraptor mongoliensis, of Jurassic Park fame.
These raptors had four toes on each foot; one
was diminutive like a cat’s dewclaw, and anoth-
er had a sickle-shaped claw and was held
above the ground while a raptor walked.
The sparrow-sized dromaeosaurs that left
these footprints would have had hips that were
only four to five centimeters high. Their tracks,
found in the South Korean city of Jinju, were
de scribed last November in Scientific Reports by
a team led by Kyung Soo Kim of the country’s
Chinju National University of Education.
The prints look like they were left by an adult
dinosaur smaller than any known type other
than birds, Romilio says. Still, the possibility
remains that a clutch of dinosaur chicks could
have made them; similar footprints 10 times big-
ger—possibly from an adult—have been found
at a site 30 kilometers away. Skeletal fossil evi-
dence from the region is needed to pin down
which hypothesis is correct, Romilio notes.
“Most people expect dinosaur tracks to be
huge, bathtublike depressions, and some
dinosaurs did leave some pretty big holes in
the ground,” says Anthony Martin, a paleon-
tologist at Emory University who studies trace
fossils (such as footprints and burrows) and
was not involved in the study. But the new
finding “shows us that we also sometimes
need to think small.” Even if the footprints
were left by hatchlings, he adds, they hint that
these juvenile dinosaurs were precocious and
able to leave their nest soon after hatching,
similar to some modern birds. — John Pickrellsad0419Adva3p.indd 13 2/20/19 5:01 PM
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