Sinosauropteryx
Three specimens have been assigned to "Sinosauropteryx prima": the holotype GMV 2123 (and its counter slab [opposite face], NIGP 127586), NIGP 127587, and D 2141. Another specimen, IVPP V14202, was assigned to the genus but not to the only species by Zhang and colleagues. The assignment of an additional larger specimen to "S. prima", GMV 2124, was later found to be in error. All of the fossils were found in the Jianshangou or Dawangzhangzi Beds of the Yixian Formation in the Beipiao and Lingyuan regions of Liaoning, China. These fossil beds have been dated to 124.6–122 million years ago, during the early Aptian stage of the Early Cretaceous.
Yi (dinosaur)
The only known "Yi qi" fossil was found in rocks assigned to the Tiaojishan Formation, dating to the Callovian-Oxfordian age of the Middle-Late Jurassic, dated to between 165 and 153 million years ago. This is the same formation (and around the same age) as the other known scansoriopterygids "Epidexipteryx" and "Scansoriopteryx". The ecosystem preserved in the Tiaojishan Formation is a forest dominated by bennettitales, ginkgo trees, conifers, and leptosporangiate ferns. These forests surrounded large lakes in the shadow of active volcanoes, ash from which was responsible for the remarkable preservation of many of the fossils. Based on the Tiajishan's plant life, its climate would have been subtropical to temperate, warm and humid. Other vertebrate fossils found in the same rock quarry as "Yi qi", which would have been close contemporaries, included salamanders like "Chunerpeton tianyiensis", the flying pterosaurs "Changchengopterus pani", "Dendrorhynchoides mutoudengensis", and "Qinglongopterus guoi", as well as the early gliding mammaliaform species "Arboroharamiya jenkinsi".