Stegosaurs

Evolutionary history

From the Early Cretaceous, far fewer finds are known, and it seems that the group had declined in diversity. Some fragmentary fossils have been described, such as Craterosaurus from England, Paranthodon from South Africa, and indeterminate remains from the Late JurassicCañadón Calcáreo Formation of Argentina. Up until recently, the only substantial discoveries were those of Wuerhosaurus from Northern China, the exact age of which is highly uncertain More recent discoveries from Asia however would later begin to fill out the Early Cretaceous diversity of the group. Indeterminate stegosaurs are known from the Early Cretaceous of Siberia, including the Ilek Formation and Batylykh Formation. The youngest known definitive remains of stegosaurs are those of Mongolostegus from Mongolia, a stegosaurine from the Hekou Group of China, and Yanbeilong of the Zuoyun Formation of China, all of which date to the Aptian-Albian.