The Châtelperronian period refers to one of five stone tool industries identified within the Upper Paleolithic period of Europe (ca 45,000-20,000 years ago). Once thought the earliest of the five industries, the Châtelperronian is today recognized as roughly coeval with or perhaps somewhat later than than the Aurignacian period: both are associated with the Middle Paleolithic to Upper Paleolithic transition, ca. 45,000-33,000 years ago. During that transition, the last Neanderthals in Europe died out, the result of a not-necessarily-peaceful cultural transition of European ownership from the long-established Neanderthal residents to the new influx of early modern humans from Africa.
When first described and defined in the early twentieth century, the Châtelperronian was believed to be the work of early modern humans (then called Cro Magnon), who, it was thought had descended directly from Neanderthals. The split between Middle and Upper Paleolithic is a distinct one, with great advances in the range of stone tool types and also with raw materials–the Upper Paleolithic period has tools and objects made of bone, teeth, ivory and antler, none of which was seen in the Middle Paleolithic.
The change is technology is today associated with the entrance of early modern humans from Africa into Europe.However, the discovery of Neanderthals at Saint Cesaire (aka La Roche a Pierrot) and Grotte du Renne (aka Arcy-sur-Cure) in direct association with Châtelperronian artifacts, led to the original debates: who made the Châtelperronian tools? More here: Chatelperronian Transition to Upper Paleolithic