New research coming from the University of Bristol suggests that, similar to a toddler who moves around on all fours before developing to walking on two feet, the Psittacosaurus, or “parrot” dinosaur similarly started off walking on four feet and then graduated to two.

Qi Zhao, a Ph.D student at the University of Bristol and a researcher at the Institute for Vertebrate Paleontology in Beijing, studied a total of 16 fossil specimens ranging in from less than 1 year old to 10 years old. He found that the 1-year-old Psittacosaurus specimens had long arms and short legs, meaning that the toddler dinosaur was biologically equipped to walk on all fours.

Paleontologists were able to shed new light on how representatives of this species changed as they aged after analyzing the fossilized remains of specimens of various ages. It appears that, up until they reached the age of four, the upper limbs of parrot dinosaurs developed at rather fast rates.

The University of Bristol provides details:

The one-year-olds had long arms and short legs, and scuttled about on all fours soon after hatching. The bone sections showed that the arm bones were growing fastest when the animals were ages one to three years. Then, from four to six years, arm growth slowed down, and the leg bones showed a massive growth spurt, meaning they ended up twice as long as the arms, necessary for an animal that stood up on its hind legs as an adult.