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.
Sarcosuchus
The remains of "S. imperator" were found in a region of the Ténéré Desert named Gadoufaoua, more specifically in the Elrhaz Formation of the Tegama Group, dating from the late Aptian to the early Albian of the Early Cretaceous, approximately 112 million years ago. The stratigraphy of the region and the aquatic fauna that was found therein indicates that it was an inland fluvial environment, entirely freshwater in nature with a humid tropical climate. "S. imperator" shared the waters with the holostean fish "Lepidotus" and the coelacanth "Mawsonia". The dinosaur fauna was represented by the iguanodontian "Lurdusaurus", which was the most common dinosaur in the region, and its relative "Ouranosaurus"; there were also two sauropods, "Nigersaurus" and a currently unnamed sauropod while the theropod fauna included the spinosaurid "Suchomimus," the carcharodontosaurid "Eocarcharia" and the abelisaurid "Kryptops".