Beginning in the 1950s, Russian paleontologists began excavating "Psittacosaurus" remains at a locality near the village of Shestakovo in the oblast of Kemerovo in Siberia. Two other nearby localities were explored in the 1990s, one of which produced several complete skeletons. This species was named "P. sibiricus" in 2000 in a scientific paper written by five Russian paleontologists, but credit for the name is officially given to two of those authors, Alexei Voronkevich and Alexander Averianov. The remains were not completely described until 2006. Two nearly complete, articulated skeletons and a variety of disarticulated material from other individuals of all ages are known from the Ilek Formation of Siberia, which ranges from the Aptian to Albian stages of the Early Cretaceous.