Paleontologists Observe Psittacosaurus Growth Through Fossil Studies
June 28, 2013

Paleontologists Observe Psittacosaurus Growth Through Fossil Studies

Lee Rannals for - Your Universe Online

Paleontologists from around the globe have shown how the "parrot dinosaur" switched from four feet to two as it grew.

Scientists from several universities wrote in the journal Nature Communications about how a Psittacosaurus would grow. These dinosaurs are one of the best-known dinosaurs, with more than 1,000 specimens found from the Cretaceous period in China and other parts of East Asia.

The team sectioned two arm and two leg bones from 16 individual dinosaurs, ranging in age from less than one year to 10-years-old, which is when they would have been fully grown.

"Some of the bones from baby Psittacosaurus were only a few millimeters across, so I had to handle them extremely carefully to be able to make useful bone sections," said Qi Zhao of the University of Bristol. "I also had to be sure to cause as little damage to these valuable specimens as possible."

The one-year-old dinosaur had long arms and short legs, and moved around 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.

Psittacosaurus ranging from four to six years had slower arm growth, but the leg bones showed a massive growth spurt where they ended up twice as long as the arms. Eventually Psittacosaurus moved from a quadrupedal lifestyle to becoming an upright bipedal dinosaur.

"This remarkable study, the first of its kind, shows how much information is locked in the bones of dinosaurs. We are delighted the study worked so well, and see many ways to use the new methods to understand even more about the astonishing lives of the dinosaurs," said Professor Xing Xu of the Beijing Institute.

Professor Mike Benton of the University of Bristol said studies like this can shed some light on the evolution of a dinosaur like Psittacosaurus.

"Having four-legged babies and juveniles suggests that at some time in their ancestry, both juveniles and adults were also four-legged, and Psittacosaurus and dinosaurs in general became secondarily bipedal," Benton said.

According to a University of Chicago study, Psittacosaurus is the first dinosaur species that mainly ate nuts. Paleontologist Paul Sereno said in 2009 that this dinosaur had a huge pile of stomach stones to grind away at whatever it eats.