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.
Corythosaurus
Fossils have been found in the upper Oldman Formation and lower Dinosaur Park Formation of Canada. The Oldman Formation dates to the Campanian, about 77.5 to 76.5 million years ago, and the Dinosaur Park Formation dates from 76.6 to 74.8 million years ago. "Corythosaurus" lived from ~77–75.7 million years ago. In the Dinosaur Park Formation "C. casuarius" lived from 76.6 to 75.9 mya, with "C. intermedius" living from 75.8 to 75.7 mya. In the Oldman Formation "C. casuarius", the only species of "Corythosaurus" from the deposits, lived about 77 to 76.5 mya. The holotype specimen was clearly a carcass that had floated up on a beach, as "Unio" shells, water-worn bones, and a baenid turtle were preserved all around. "Corythosaurus" probably lived in a woodland forest, and might have occasionally wandered into swampy areas.