In 1982, Russell created the "dinosauroid" thought experiment, which speculated an evolutionary path for Troodon if it had not gone extinct in the Cretaceous–Paleogene extinction event 65 million years ago, and had instead evolved into intelligent beings. Russell commissioned a model of his dinosauroid by Artist Ron Sequin, and the concept became popular. Various later anthropologists have continued Russell's speculations about intelligent Troodon-like dinosaurs, though they often find his original idea too anthropomorphic.